Monday, 28 December 2015
Core java assignment restaurant’s resources 68024_Scenario7
Foodies Delight is a restaurant chain that has its head office in Denver, Colorado. Foodies Delight has 25 restaurants across seven major cities nationwide and plans to add more restaurants to its chain. Because of the quality of food and service that Foodies Delight provides, almost all their restaurants attract a good number of customers.
To dine in a restaurant, customers need to reserve a table either by calling the restaurant over the phone or by visiting the restaurant. Currently, table reservation details of a customer are recorded and processed manually. This manual process often leads to errors that result in customer disappointment. A common complaint is regarding a customer who is not able to get a table, which he has already reserved, on time. In addition, tables, at times, remain unused despite customer’s availability, which results in wastage of restaurant’s resources.
Based on the feedbacks received from the customers and restaurant staff, the management of Foodies Delight has decided to automate the table reservation process through a Reservation Management System (RMS).
To create the RMS, the management has approached Tech Force, a software development organization. As a software developer of Tech Force, you have been assigned the task to lead the team creating the RMS.
Based on your initial meeting with the management and restaurant staff of Foodies Delight, you have analyzed that each restaurant has the following types of tables: Single Double Family
The restaurant receptionist reserves tables for customers. To reserve a table, the receptionist checks for the availability of tables, whenever there is a reservation request. When customers leave a table after paying the bill, the receptionist marks each such table as unreserved.
In subsequent meetings, you have collated the requirements of the RMS. The RMS will be a standalone application used by the receptionist of a restaurant. The RMS should allow a receptionist to check the availability of a table and to reserve a table for a customer. The RMS should allow the receptionist to generate Table Reservation Report (TRR) files for each table category and store the same in the file system as text files. A TRR will contain the following pieces of information: The date and time on which the report is created The table ID and the duration for which the table is occupied
The RMS should also allow the receptionist to merge all the TRR files of a week to create a single Weekly Reservation Report (WRR) file. At the end of the week, the receptionist will share the WRR file with the Restaurant Manager.
You have been assigned the task of analyzing the scenario and lead the team in creating the RMS.
To dine in a restaurant, customers need to reserve a table either by calling the restaurant over the phone or by visiting the restaurant. Currently, table reservation details of a customer are recorded and processed manually. This manual process often leads to errors that result in customer disappointment. A common complaint is regarding a customer who is not able to get a table, which he has already reserved, on time. In addition, tables, at times, remain unused despite customer’s availability, which results in wastage of restaurant’s resources.
Based on the feedbacks received from the customers and restaurant staff, the management of Foodies Delight has decided to automate the table reservation process through a Reservation Management System (RMS).
To create the RMS, the management has approached Tech Force, a software development organization. As a software developer of Tech Force, you have been assigned the task to lead the team creating the RMS.
Based on your initial meeting with the management and restaurant staff of Foodies Delight, you have analyzed that each restaurant has the following types of tables: Single Double Family
The restaurant receptionist reserves tables for customers. To reserve a table, the receptionist checks for the availability of tables, whenever there is a reservation request. When customers leave a table after paying the bill, the receptionist marks each such table as unreserved.
In subsequent meetings, you have collated the requirements of the RMS. The RMS will be a standalone application used by the receptionist of a restaurant. The RMS should allow a receptionist to check the availability of a table and to reserve a table for a customer. The RMS should allow the receptionist to generate Table Reservation Report (TRR) files for each table category and store the same in the file system as text files. A TRR will contain the following pieces of information: The date and time on which the report is created The table ID and the duration for which the table is occupied
The RMS should also allow the receptionist to merge all the TRR files of a week to create a single Weekly Reservation Report (WRR) file. At the end of the week, the receptionist will share the WRR file with the Restaurant Manager.
You have been assigned the task of analyzing the scenario and lead the team in creating the RMS.
Core java assignment patient with a doctor 67854_Scenario1
NemCare is a leading health care provider in the US and has multispecialty hospitals in seven cities nationwide. In its effort to reach out to people who do not have access to medical facilities, NemCare has decided to operate Out Patient Clinics. Each NemCare clinic will have a qualified medical team that provides consultations to patients visiting the clinic. NemCare has already started work to make two clinics operational within six months. Having realized the need to automate the operations of the clinics, the management of NemCare has hired ProDev, an IT consultancy firm, to design and automate the processes common to each clinic. In the first phase, NemCare has assigned ProDev to create Patient Management System (PMS).
You have been assigned to lead a team to design and develop PMS. Based on the initial requirement, you have documented that each clinic will initially have the following departments with more departments likely to be added in a phased manner:
General Medicine Cardiology Neurology Gastroenterology
Each department will have a team of doctors with different consultancy timings.
In subsequent meetings, you have gathered the requirements of PMS. Initially, PMS will be a single user application that allows an employee of a clinic to register a new patient visiting the clinic and generate a unique patient ID for the patient. The clinic will provide a printed registration card to the patient. During subsequent visits to the clinic, the patient will be required to provide the registration card for appointments or any other transactions.
The system should allow an employee to create an appointment for a registered patient with a doctor. The system should create a unique appointment file for each patient that will be updated when the patient revisits the clinic. Each appointment file should be stored categorically by the departments of the clinic. For a revisiting patient, the system should allow an employee to view the appointment file of the patient. Being the team leader at ProDev, you have been assigned the task of analyzing the scenario and lead the team in creating PMS.
You have been assigned to lead a team to design and develop PMS. Based on the initial requirement, you have documented that each clinic will initially have the following departments with more departments likely to be added in a phased manner:
General Medicine Cardiology Neurology Gastroenterology
Each department will have a team of doctors with different consultancy timings.
In subsequent meetings, you have gathered the requirements of PMS. Initially, PMS will be a single user application that allows an employee of a clinic to register a new patient visiting the clinic and generate a unique patient ID for the patient. The clinic will provide a printed registration card to the patient. During subsequent visits to the clinic, the patient will be required to provide the registration card for appointments or any other transactions.
The system should allow an employee to create an appointment for a registered patient with a doctor. The system should create a unique appointment file for each patient that will be updated when the patient revisits the clinic. Each appointment file should be stored categorically by the departments of the clinic. For a revisiting patient, the system should allow an employee to view the appointment file of the patient. Being the team leader at ProDev, you have been assigned the task of analyzing the scenario and lead the team in creating PMS.
Collections in Java
OOP: Collections 1
Collections in Java
• Arrays n Has special language support • Iterators n Iterator (i) • Collections (also called containers) n Collection (i) n Set (i), u HashSet (c), TreeSet (c) n List (i), u ArrayList (c), LinkedList (c) n Map (i), u HashMap (c), TreeMap (c)
OOP: Collections 2
Array • Most efficient way to hold references to objects.
• Advantages n An array know the type it holds, i.e., compile-time type checking. n An array know its size, i.e., ask for the length. n An array can hold primitive types directly. • Disadvantages n An array can only hold one type of objects (including primitives). n Arrays are fixed size.
2
Car 3 4 5
Car 6 7
Car 1
Car 0index data
OOP: Collections 3
Array, Example
• Helper class java.util.Arrays n Search and sort: binarySearch(), sort() n Comparison: equals() (many overloaded) n Instantiation: fill() (many overloaded) n Conversion: asList()
class Car{}; // minimal dummy class Car[] cars1; // null reference Car[] cars2 = new Car[10]; // null references
for (int i = 0; i < cars2.length; i++) cars2[i] = new Car();
// Aggregated initialization Car[] cars3 = {new Car(), new Car(), new Car(), new Car()}; cars1 = {new Car(), new Car(), new Car()};
OOP: Collections 4
Overview of Collection • A collection is a group of data manipulate as a single object. Corresponds to a bag.
• Insulate client programs from the implementation. n array, linked list, hash table, balanced binary tree • Like C++'s Standard Template Library (STL) • Can grow as necessary. • Contain only Objects (reference types). • Heterogeneous. • Can be made thread safe (concurrent access). • Can be made not-modifiable.
OOP: Collections 5
Collection Interfaces • Collections are primarily defined through a set of interfaces. n Supported by a set of classes that implement the interfaces
• Interfaces are used of flexibility reasons n Programs that uses an interface is not tightened to a specific implementation of a collection. n It is easy to change or replace the underlying collection class with another (more efficient) class that implements the same interface.
[Source: java.sun.com]
OOP: Collections 6
Collection Interfaces and Classes
[Source: bruceeckel.com]
OOP: Collections 7
The Iterator Interface • The idea: Select each element in a collection n Hide the underlying collection
Iterator hasNext() next() remove()
Collection isEmpty() add() remove() ...
list
• Iterators are fail-fast n Exception thrown if collection is modified externally, i.e., not via the iterator (multi-threading).
OOP: Collections 8
The Iterator Interface, cont.
// an example public static void main (String[] args){ ArrayList cars = new ArrayList(); for (int i = 0; i < 12; i++) cars.add (new Car());
Iterator it = cats.iterator(); while (it.hasNext()) System.out.println ((Car)it.next());
}
// the interface definition Interface Iterator { boolean hasNext(); Object next(); // note "one-way" traffic void remove(); }
OOP: Collections 9
The Collection Interface
public interface Collection { // Basic Operations int size(); boolean isEmpty(); boolean contains(Object element); boolean add(Object element); // Optional boolean remove(Object element); // Optional Iterator iterator();
// Bulk Operations boolean containsAll(Collection c); boolean addAll(Collection c); // Optional boolean removeAll(Collection c); // Optional boolean retainAll(Collection c); // Optional void clear(); // Optional
// Array Operations Object[] toArray(); Object[] toArray(Object a[]); }
OOP: Collections 10
The Set Interface • Corresponds to the mathematical definition of a set (no duplicates are allowed).
• Compared to the Collection interface n Interface is identical. n Every constructor must create a collection without duplicates. n The operation add cannot add an element already in the set. n The method call set1.equals(set2) works at follows u set1 ⊆ set2, and set2 ⊆ set1
OOP: Collections 11
Set Idioms
• set1 ∪ set2 n set1.addAll(set2) • set1 ∩ set2 n set1.retainAll(set2) • set1 − set2 n set1.removeAll(set2)
OOP: Collections 12
HashSet and TreeSet Classes • HashSet and TreeSet implement the interface Set.
• HashSet n Implemented using a hash table. n No ordering of elements. n add, remove, and contains methods constant time complexity O(c).
• TreeSet n Implemented using a tree structure. n Guarantees ordering of elements. n add, remove, and contains methods logarithmic time complexity O(log (n)), where n is the number of elements in the set.
OOP: Collections 13
HashSet, Example
// [Source: java.sun.com] import java.util.*; public class FindDups { public static void main(String args[]){ Set s = new HashSet(); for (int i = 0; i < args.length; i++){ if (!s.add(args[i])) System.out.println("Duplicate detected: " + args[i]); } System.out.println(s.size() + " distinct words detected: " + s); } }
OOP: Collections 14
The List Interface • The List interface corresponds to an order group of elements. Duplicates are allowed.
• Extensions compared to the Collection interface n Access to elements via indexes, like arrays u add (int, Object), get(int), remove(int), set(int, Object) (note set = replace bad name for the method) n Search for elements u indexOf(Object), lastIndexOf(Object) n Specialized Iterator, call ListIterator n Extraction of sublist u subList(int fromIndex, int toIndex)
OOP: Collections 15
The List Interface, cont. Further requirements compared to the Collection Interface • add(Object)adds at the end of the list. • remove(Object)removes at the start of the list. • list1.equals(list2)the ordering of the elements is taken into consideration. • Extra requirements to the method hashCode. n list1.equals(list2) implies that list1.hashCode()==list2.hashCode()
OOP: Collections 16
The List Interface, cont.
public interface List extends Collection { // Positional Access Object get(int index); Object set(int index, Object element); // Optional void add(int index, Object element); // Optional Object remove(int index); // Optional abstract boolean addAll(int index, Collection c); // Optional
// Search int indexOf(Object o); int lastIndexOf(Object o);
// Iteration ListIterator listIterator(); ListIterator listIterator(int index);
// Range-view List subList(int from, int to); }
OOP: Collections 17
ArrayList and LinkedList Classes • The classes ArrayList and LinkedList implement the List interface.
• ArrayList is an array based implementation where elements can be accessed directly via the get and set methods. n Default choice for simple sequence.
• LinkedList is based on a double linked list n Gives better performance on add and remove compared to ArrayList. n Gives poorer performance on get and set methods compared to ArrayList.
OOP: Collections 18
ArrayList, Example
// [Source: java.sun.com] import java.util.*;
public class Shuffle { public static void main(String args[]) { List l = new ArrayList(); for (int i = 0; i < args.length; i++) l.add(args[i]); Collections.shuffle(l, new Random()); System.out.println(l); } }
OOP: Collections 19
LinkedList, Example
import java.util.*; public class MyStack { private LinkedList list = new LinkedList(); public void push(Object o){ list.addFirst(o); } public Object top(){ return list.getFirst(); } public Object pop(){ return list.removeFirst(); }
public static void main(String args[]) { Car myCar; MyStack s = new MyStack(); s.push (new Car()); myCar = (Car)s.pop(); } }
OOP: Collections 20
The ListIterator Interface
public interface ListIterator extends Iterator { boolean hasNext(); Object next();
boolean hasPrevious(); Object previous();
int nextIndex(); int previousIndex();
void remove(); // Optional void set(Object o); // Optional void add(Object o); // Optional }
OOP: Collections 21
The Map Interface • A Map is an object that maps keys to values. Also called an associative array or a dictionary.
• Methods for adding and deleting n put(Object key, Object value) n remove (Object key) • Methods for extraction objects n get (Object key) • Methods to retrieve the keys, the values, and (key, value) pairs n keySet() // returns a Set n values() // returns a Collection, n entrySet() // returns a set
OOP: Collections 22
The MAP Interface, cont. public interface Map { // Basic Operations Object put(Object key, Object value); Object get(Object key); Object remove(Object key); boolean containsKey(Object key); boolean containsValue(Object value); int size(); boolean isEmpty(); // Bulk Operations void putAll(Map t); void clear(); // Collection Views public Set keySet(); public Collection values(); public Set entrySet(); // Interface for entrySet elements public interface Entry { Object getKey(); Object getValue(); Object setValue(Object value); } }
OOP: Collections 23
HashMap and TreeMap Classes • The HashMap and HashTree classes implement the Map interface.
• HashMap n The implementation is based on a hash table. n No ordering on (key, value) pairs.
• TreeMap n The implementation is based on red-black tree structure. n (key, value) pairs are ordered on the key.
OOP: Collections 24
HashMap, Example
import java.util.*;
public class Freq { private static final Integer ONE = new Integer(1); public static void main(String args[]) { Map m = new HashMap();
// Initialize frequency table from command line for (int i=0; i < args.length; i++) { Integer freq = (Integer) m.get(args[i]); m.put(args[i], (freq==null ? ONE : new Integer(freq.intValue() + 1))); }
System.out.println(m.size()+ " distinct words detected:"); System.out.println(m); } }
OOP: Collections 25
Static Methods on Collections • Collection n Search and sort: binarySearch(), sort() n Reorganization: reverse(), shuffle() n Wrappings: unModifiableCollection, synchonizedCollection
OOP: Collections 26
Collection Advantages and Disadvantages Advantages • Can hold different types of objects. • Resizable Disadvantages • Must cast to correct type • Cannot do compile-time type checking.
OOP: Collections 27
Summary
• Array n Holds objects of known type. n Fixed size.
• Collections n Generalization of the array concept. n Set of interfaces defined in Java for storing object. n Multiple types of objects. n Resizable.
• Queue, Stack, Deque classes absent n Use LinkedList.
Collections in Java
• Arrays n Has special language support • Iterators n Iterator (i) • Collections (also called containers) n Collection (i) n Set (i), u HashSet (c), TreeSet (c) n List (i), u ArrayList (c), LinkedList (c) n Map (i), u HashMap (c), TreeMap (c)
OOP: Collections 2
Array • Most efficient way to hold references to objects.
• Advantages n An array know the type it holds, i.e., compile-time type checking. n An array know its size, i.e., ask for the length. n An array can hold primitive types directly. • Disadvantages n An array can only hold one type of objects (including primitives). n Arrays are fixed size.
2
Car 3 4 5
Car 6 7
Car 1
Car 0index data
OOP: Collections 3
Array, Example
• Helper class java.util.Arrays n Search and sort: binarySearch(), sort() n Comparison: equals() (many overloaded) n Instantiation: fill() (many overloaded) n Conversion: asList()
class Car{}; // minimal dummy class Car[] cars1; // null reference Car[] cars2 = new Car[10]; // null references
for (int i = 0; i < cars2.length; i++) cars2[i] = new Car();
// Aggregated initialization Car[] cars3 = {new Car(), new Car(), new Car(), new Car()}; cars1 = {new Car(), new Car(), new Car()};
OOP: Collections 4
Overview of Collection • A collection is a group of data manipulate as a single object. Corresponds to a bag.
• Insulate client programs from the implementation. n array, linked list, hash table, balanced binary tree • Like C++'s Standard Template Library (STL) • Can grow as necessary. • Contain only Objects (reference types). • Heterogeneous. • Can be made thread safe (concurrent access). • Can be made not-modifiable.
OOP: Collections 5
Collection Interfaces • Collections are primarily defined through a set of interfaces. n Supported by a set of classes that implement the interfaces
• Interfaces are used of flexibility reasons n Programs that uses an interface is not tightened to a specific implementation of a collection. n It is easy to change or replace the underlying collection class with another (more efficient) class that implements the same interface.
[Source: java.sun.com]
OOP: Collections 6
Collection Interfaces and Classes
[Source: bruceeckel.com]
OOP: Collections 7
The Iterator Interface • The idea: Select each element in a collection n Hide the underlying collection
Iterator hasNext() next() remove()
Collection isEmpty() add() remove() ...
list
• Iterators are fail-fast n Exception thrown if collection is modified externally, i.e., not via the iterator (multi-threading).
OOP: Collections 8
The Iterator Interface, cont.
// an example public static void main (String[] args){ ArrayList cars = new ArrayList(); for (int i = 0; i < 12; i++) cars.add (new Car());
Iterator it = cats.iterator(); while (it.hasNext()) System.out.println ((Car)it.next());
}
// the interface definition Interface Iterator { boolean hasNext(); Object next(); // note "one-way" traffic void remove(); }
OOP: Collections 9
The Collection Interface
public interface Collection { // Basic Operations int size(); boolean isEmpty(); boolean contains(Object element); boolean add(Object element); // Optional boolean remove(Object element); // Optional Iterator iterator();
// Bulk Operations boolean containsAll(Collection c); boolean addAll(Collection c); // Optional boolean removeAll(Collection c); // Optional boolean retainAll(Collection c); // Optional void clear(); // Optional
// Array Operations Object[] toArray(); Object[] toArray(Object a[]); }
OOP: Collections 10
The Set Interface • Corresponds to the mathematical definition of a set (no duplicates are allowed).
• Compared to the Collection interface n Interface is identical. n Every constructor must create a collection without duplicates. n The operation add cannot add an element already in the set. n The method call set1.equals(set2) works at follows u set1 ⊆ set2, and set2 ⊆ set1
OOP: Collections 11
Set Idioms
• set1 ∪ set2 n set1.addAll(set2) • set1 ∩ set2 n set1.retainAll(set2) • set1 − set2 n set1.removeAll(set2)
OOP: Collections 12
HashSet and TreeSet Classes • HashSet and TreeSet implement the interface Set.
• HashSet n Implemented using a hash table. n No ordering of elements. n add, remove, and contains methods constant time complexity O(c).
• TreeSet n Implemented using a tree structure. n Guarantees ordering of elements. n add, remove, and contains methods logarithmic time complexity O(log (n)), where n is the number of elements in the set.
OOP: Collections 13
HashSet, Example
// [Source: java.sun.com] import java.util.*; public class FindDups { public static void main(String args[]){ Set s = new HashSet(); for (int i = 0; i < args.length; i++){ if (!s.add(args[i])) System.out.println("Duplicate detected: " + args[i]); } System.out.println(s.size() + " distinct words detected: " + s); } }
OOP: Collections 14
The List Interface • The List interface corresponds to an order group of elements. Duplicates are allowed.
• Extensions compared to the Collection interface n Access to elements via indexes, like arrays u add (int, Object), get(int), remove(int), set(int, Object) (note set = replace bad name for the method) n Search for elements u indexOf(Object), lastIndexOf(Object) n Specialized Iterator, call ListIterator n Extraction of sublist u subList(int fromIndex, int toIndex)
OOP: Collections 15
The List Interface, cont. Further requirements compared to the Collection Interface • add(Object)adds at the end of the list. • remove(Object)removes at the start of the list. • list1.equals(list2)the ordering of the elements is taken into consideration. • Extra requirements to the method hashCode. n list1.equals(list2) implies that list1.hashCode()==list2.hashCode()
OOP: Collections 16
The List Interface, cont.
public interface List extends Collection { // Positional Access Object get(int index); Object set(int index, Object element); // Optional void add(int index, Object element); // Optional Object remove(int index); // Optional abstract boolean addAll(int index, Collection c); // Optional
// Search int indexOf(Object o); int lastIndexOf(Object o);
// Iteration ListIterator listIterator(); ListIterator listIterator(int index);
// Range-view List subList(int from, int to); }
OOP: Collections 17
ArrayList and LinkedList Classes • The classes ArrayList and LinkedList implement the List interface.
• ArrayList is an array based implementation where elements can be accessed directly via the get and set methods. n Default choice for simple sequence.
• LinkedList is based on a double linked list n Gives better performance on add and remove compared to ArrayList. n Gives poorer performance on get and set methods compared to ArrayList.
OOP: Collections 18
ArrayList, Example
// [Source: java.sun.com] import java.util.*;
public class Shuffle { public static void main(String args[]) { List l = new ArrayList(); for (int i = 0; i < args.length; i++) l.add(args[i]); Collections.shuffle(l, new Random()); System.out.println(l); } }
OOP: Collections 19
LinkedList, Example
import java.util.*; public class MyStack { private LinkedList list = new LinkedList(); public void push(Object o){ list.addFirst(o); } public Object top(){ return list.getFirst(); } public Object pop(){ return list.removeFirst(); }
public static void main(String args[]) { Car myCar; MyStack s = new MyStack(); s.push (new Car()); myCar = (Car)s.pop(); } }
OOP: Collections 20
The ListIterator Interface
public interface ListIterator extends Iterator { boolean hasNext(); Object next();
boolean hasPrevious(); Object previous();
int nextIndex(); int previousIndex();
void remove(); // Optional void set(Object o); // Optional void add(Object o); // Optional }
OOP: Collections 21
The Map Interface • A Map is an object that maps keys to values. Also called an associative array or a dictionary.
• Methods for adding and deleting n put(Object key, Object value) n remove (Object key) • Methods for extraction objects n get (Object key) • Methods to retrieve the keys, the values, and (key, value) pairs n keySet() // returns a Set n values() // returns a Collection, n entrySet() // returns a set
OOP: Collections 22
The MAP Interface, cont. public interface Map { // Basic Operations Object put(Object key, Object value); Object get(Object key); Object remove(Object key); boolean containsKey(Object key); boolean containsValue(Object value); int size(); boolean isEmpty(); // Bulk Operations void putAll(Map t); void clear(); // Collection Views public Set keySet(); public Collection values(); public Set entrySet(); // Interface for entrySet elements public interface Entry { Object getKey(); Object getValue(); Object setValue(Object value); } }
OOP: Collections 23
HashMap and TreeMap Classes • The HashMap and HashTree classes implement the Map interface.
• HashMap n The implementation is based on a hash table. n No ordering on (key, value) pairs.
• TreeMap n The implementation is based on red-black tree structure. n (key, value) pairs are ordered on the key.
OOP: Collections 24
HashMap, Example
import java.util.*;
public class Freq { private static final Integer ONE = new Integer(1); public static void main(String args[]) { Map m = new HashMap();
// Initialize frequency table from command line for (int i=0; i < args.length; i++) { Integer freq = (Integer) m.get(args[i]); m.put(args[i], (freq==null ? ONE : new Integer(freq.intValue() + 1))); }
System.out.println(m.size()+ " distinct words detected:"); System.out.println(m); } }
OOP: Collections 25
Static Methods on Collections • Collection n Search and sort: binarySearch(), sort() n Reorganization: reverse(), shuffle() n Wrappings: unModifiableCollection, synchonizedCollection
OOP: Collections 26
Collection Advantages and Disadvantages Advantages • Can hold different types of objects. • Resizable Disadvantages • Must cast to correct type • Cannot do compile-time type checking.
OOP: Collections 27
Summary
• Array n Holds objects of known type. n Fixed size.
• Collections n Generalization of the array concept. n Set of interfaces defined in Java for storing object. n Multiple types of objects. n Resizable.
• Queue, Stack, Deque classes absent n Use LinkedList.
JDBC TEST
package jdbctest;
import java.sql.*;
public class JDBCTEST {
public static void main(String[] args)throws SQLException {
Connection myConn = null;
Statement myStmt = null;
ResultSet myRs = null;
try {
// 1. Get a connection to database
myConn = DriverManager.getConnection("jdbc:mysql://localhost:3306/College", "root" , "niit");
System.out.println("Database connection successful!\n");
// 2. Create a statement
myStmt = myConn.createStatement();
// 3. Execute SQL query
myRs = myStmt.executeQuery("select * from student");
// 4. Process the result set
while (myRs.next()) {
System.out.println(myRs.getString("id") + ", " + myRs.getString("name"));
}
}
catch(Exception e)
{}
}
}
import java.sql.*;
public class JDBCTEST {
public static void main(String[] args)throws SQLException {
Connection myConn = null;
Statement myStmt = null;
ResultSet myRs = null;
try {
// 1. Get a connection to database
myConn = DriverManager.getConnection("jdbc:mysql://localhost:3306/College", "root" , "niit");
System.out.println("Database connection successful!\n");
// 2. Create a statement
myStmt = myConn.createStatement();
// 3. Execute SQL query
myRs = myStmt.executeQuery("select * from student");
// 4. Process the result set
while (myRs.next()) {
System.out.println(myRs.getString("id") + ", " + myRs.getString("name"));
}
}
catch(Exception e)
{}
}
}
ISAS PRESENTATION ULRA BOOK
ISAS PRESENTATION ULRA BOOK
Hard copy
https://drive.google.com/file/d/0B_k0mGjeovElMHNhX28zMG1QcW8/view?usp=sharing
PPT
https://drive.google.com/file/d/0B_k0mGjeovElSGRHdVpMUW9RV0E/view?usp=sharing
Top 50 C# Interview Questions and Answers for freshers
Top 50 C# Interview Questions and Answers for freshers and experienced are below are below :
1. What is C#?
--> C# is an object oriented, type safe and managed language that is compiled by .Net framework to generate Microsoft Intermediate Language.
2. What are the types of comment in C# with examples?--> Single line
Eg:
[csharp] //This is a Single line comment[/csharp]
ii. Multiple line (/* */)
Eg:
[csharp] /*This is a multiple line comment
We are in line 2Last line of comment*/[/csharp]
iii. XML Comments (///).
Eg:
[csharp]/// summary;
/// Set error message for multilingual language.
/// summary[/csharp]
3. Can multiple catch blocks be executed?
--> No, Multiple catch blocks can’t be executed. Once the proper catch code executed, the control is transferred to the finally block and then the code that follows the finally block gets executed.
4. What is the difference between public, static and void?
--> All these are access modifiers in C#. Public declared variables or methods are accessible anywhere in the application. Static declared variables or methods are globally accessible without creating an instance of the class. The compiler stores the address of the method as the entry point and uses this information to begin execution before any objects are created. And Void is a type modifier that states that the method or variable does not return any value.
5. What is an object?
--> An object is an instance of a class through which we access the methods of that class. “New” keyword is used to create an object. A class that creates an object in memory will contain the information about the methods, variables and behavior of that class.
Also Read: Android Interview Ques & Ans for Fresher
6. Define Constructors?
--> A constructor is a member function in a class that has the same name as its class. The constructor is automatically invoked whenever an object class is created. It constructs the values of data members while initializing the class.
7. What is Jagged Arrays?
--> The array which has elements of type array is called jagged array. The elements can be of different dimensions and sizes. We can also call jagged array as Array of arrays.
8. What is the difference between ref & out parameters?
--> An argument passed as ref must be initialized before passing to the method whereas out parameter needs not to be initialized before passing to a method.
9. What is the use of using statement in C#?
--> The using block is used to obtain a resource and use it and then automatically dispose of when the execution of block completed.
10. What is serialization?
--> When we want to transport an object through network then we have to convert the object into a stream of bytes. The process of converting an object into a stream of bytes is called Serialization. For an object to be serializable, it should inherit ISerialize Interface.
De-serialization is the reverse process of creating an object from a stream of bytes.
Also Read: PHP Interview Questions and Answers for freshers
11. Can “this” be used within a static method?
--> We can’t use ‘This’ in a static method because we can only use static variables/methods in a static method.
12. What is difference between constants and read-only?
--> Constant variables are declared and initialized at compile time. The value can’t be changed after wards. Read-only variables will be initialized only from the Static constructor of the class. Read only is used only when we want to assign the value at run time.
13. What is an interface class?
--> Interface is an abstract class which has only public abstract methods and the methods only have the declaration and not the definition. These abstract methods must be implemented in the inherited classes.
14. What are value types and reference types?
--> Value types are stored in the Stack whereas reference types stored on heap.
Value types:
[csharp] int, enum , byte, decimal, double, float, long[/csharp]
Reference Types:
[csharp] string , class, interface, object.[/csharp]
15. What are Custom Control and User Control?
--> Custom Controls are controls generated as compiled code (Dlls), those are easier to use and can be added to toolbox. Developers can drag and drop controls to their web forms. Attributes can be set at design time. We can easily add custom controls to Multiple Applications (If Shared Dlls), If they are private then we can copy to dll to bin directory of web application and then add reference and can use them.
User Controls are very much similar to ASP include files, and are easy to create. User controls can’t be placed in the toolbox and dragged – dropped from it. They have their design and code behind. The file extension for user controls is ascx.
Also Read: OOPs Interview Questions and Answers for Fresher
16. What are sealed classes in C#?
--> We create sealed classes when we want to restrict the class to be inherited. Sealed modifier used to prevent derivation from a class. If we forcefully specify a sealed class as base class then a compile-time error occurs.
17. What is method overloading?
--> Method overloading is creating multiple methods with the same name with unique signatures in the same class. When we compile, the compiler uses overload resolution to determine the specific method to be invoke.
18. What is the difference between Array and Arraylist?
--> In an array, we can have items of the same type only. The size of the array is fixed. An arraylist is similar to an array but it doesn’t have a fixed size.
19. Can a private virtual method be overridden?
--> No, because they are not accessible outside the class.
20. Describe the accessibility modifier “protected internal”.
--> Protected Internal variables/methods are accessible within the same assembly and also from the classes that are derived from this parent class.
21. What are the differences between System.String and System.Text.StringBuilder classes?
--> System.String is immutable. When we modify the value of a string variable then a new memory is allocated to the new value and the previous memory allocation released. System.StringBuilder was designed to have concept of a mutable string where a variety of operations can be performed without allocation separate memory location for the modified string.
22. What’s the difference between the System.Array.CopyTo() and System.Array.Clone() ?
--> Using Clone() method, we creates a new array object containing all the elements in the original array and using CopyTo() method, all the elements of existing array copies into another existing array. Both the methods perform a shallow copy.
23. How can we sort the elements of the array in descending order?
--> Using Sort() methods followed by Reverse() method.
24. Write down the C# syntax to catch exception?
--> To catch an exception, we use try catch blocks. Catch block can have parameter of system.Exception type.
Eg:
[csharp]
try
{
GetAllData();
}
catch(Exception ex)
{
}[/csharp]
In the above example, we can omit the parameter from catch statement.
25. What’s the difference between an interface and abstract class?
--> Interfaces have all the methods having only declaration but no definition. In an abstract class, we can have some concrete methods. In an interface class, all the methods are public. An abstract class may have private methods.
26. What is the difference between Finalize() and Dispose() methods?
--> Dispose() is called when we want for an object to release any unmanaged resources with them. On the other hand Finalize() is used for the same purpose but it doesn’t assure the garbage collection of an object.
27. What are circular references?
--> Circular reference is situation in which two or more resources are interdependent on each other causes the lock condition and make the resources unusable.
28. What are generics in C#.NET?
--> Generics are used to make reusable code classes to decrease the code redundancy, increase type safety and performance. Using generics, we can create collection classes. To create generic collection, System.Collections.Generic namespace should be used instead of classes such as ArrayList in the System.Collections namespace. Generics promotes the usage of parameterized types.
29. What is an object pool in .NET?
--> An object pool is a container having objects ready to be used. It tracks the object that is currently in use, total number of objects in the pool. This reduces the overhead of creating and re-creating objects.
30. List down the commonly used types of exceptions in .Net?
--> ArgumentException, ArgumentNullException , ArgumentOutOfRangeException, ArithmeticException, DivideByZeroException ,OverflowException , IndexOutOfRangeException ,InvalidCastException ,InvalidOperationException , IOEndOfStreamException , NullReferenceException , OutOfMemoryException , StackOverflowException etc.
31. What are Custom Exceptions?
--> Sometimes there are some errors that need to be handeled as per user requirements. Custom exceptions are used for them and are used defined exceptions.
32. What are delegates?
--> Delegates are same are function pointers in C++ but the only difference is that they are type safe unlike function pointers. Delegates are required because they can be used to write much more generic type safe functions.
33. How do you inherit a class into other class in C#?
--> Colon is used as inheritance operator in C#. Just place a colon and then the class name.
[csharp] public class DerivedClass : BaseClass[/csharp]
34. What is the base class in .net from which all the classes are derived from?
--> [csharp]System.Object[/csharp]
35. What is the difference between method overriding and method overloading?
--> In method overriding, we change the method definition in the derived class that changes the method behavior. Method overloading is creating a method with the same name within the same class having different signatures.
36. What are the different ways a method can be overloaded?
--> Methods can be overloaded using different data types for parameter, different order of parameters, and different number of parameters.
37. Why can’t you specify the accessibility modifier for methods inside the interface?
--> In an interface, we have virtual methods that do not have method definition. All the methods are there to be overridden in the derived class. That’s why they all are public.
38. How can we set class to be inherited, but prevent the method from being over-ridden?
--> Declare the class as public and make the method sealed to prevent it from being overridden.
39. What happens if the inherited interfaces have conflicting method names?
--> Implement is up to you as the method is inside your own class. There might be problem when the methods from different interfaces expect different data, but as far as compiler cares you’re okay.
40. What is the difference between a Struct and a Class?
--> Structs are value-type variables and classes are reference types. Structs stored on the stack, causes additional overhead but faster retrieval. Structs cannot be inherited.
41. How to use nullable types in .Net?
--> Value types can take either their normal values or a null value. Such types are called nullable types.
[csharp]Int? someID = null;
If(someID.HasVAlue)
{
}
[/csharp]
42. How we can create an array with non-default values?
--> We can create an array with non-default values using Enumerable.Repeat.
43. What is difference between is and as operators in c#?
--> “is” operator is used to check the compatibility of an object with a given type and it returns the result as Boolean.
“as” operator is used for casting of object to a type or a class.
44. What’s a multicast delegate?
--> A delegate having multiple handlers assigned to it is called multicast delegate. Each handler is assigned to a method.
45. What are indexers in C# .NET?
--> Indexers are known as smart arrays in C#. It allows the instances of a class to be indexed in the same way as array.
Eg:
[csharp]public int this[int index] // Indexer declaration[/csharp]
46. What is difference between the “throw” and “throw ex” in .NET?
--> “Throw” statement preserves original error stack whereas “throw ex” have the stack trace from their throw point. It is always advised to use “throw” because it provides more accurate error information.
47. What are C# attributes and its significance?
--> C# provides developers a way to define declarative tags on certain entities eg. Class, method etc. are called attributes. The attribute’s information can be retrieved at runtime using Reflection.
48. How to implement singleton design pattern in C#?
--> In singleton pattern, a class can only have one instance and provides access point to it globally.
Eg:
[csharp]
Public sealed class Singleton
{
Private static readonly Singleton _instance = new Singleton();
}
[/csharp]
49. What is the difference between directcast and ctype?
--> DirectCast is used to convert the type of an object that requires the run-time type to be the same as the specified type in DirectCast.
Ctype is used for conversion where the conversion is defined between the expression and the type.
50. Is C# code is managed or unmanaged code?
--> C# is managed code because Common language runtime can compile C# code to Intermediate language.
1. What is C#?
--> C# is an object oriented, type safe and managed language that is compiled by .Net framework to generate Microsoft Intermediate Language.
2. What are the types of comment in C# with examples?--> Single line
Eg:
[csharp] //This is a Single line comment[/csharp]
ii. Multiple line (/* */)
Eg:
[csharp] /*This is a multiple line comment
We are in line 2Last line of comment*/[/csharp]
iii. XML Comments (///).
Eg:
[csharp]/// summary;
/// Set error message for multilingual language.
/// summary[/csharp]
3. Can multiple catch blocks be executed?
--> No, Multiple catch blocks can’t be executed. Once the proper catch code executed, the control is transferred to the finally block and then the code that follows the finally block gets executed.
4. What is the difference between public, static and void?
--> All these are access modifiers in C#. Public declared variables or methods are accessible anywhere in the application. Static declared variables or methods are globally accessible without creating an instance of the class. The compiler stores the address of the method as the entry point and uses this information to begin execution before any objects are created. And Void is a type modifier that states that the method or variable does not return any value.
5. What is an object?
--> An object is an instance of a class through which we access the methods of that class. “New” keyword is used to create an object. A class that creates an object in memory will contain the information about the methods, variables and behavior of that class.
Also Read: Android Interview Ques & Ans for Fresher
6. Define Constructors?
--> A constructor is a member function in a class that has the same name as its class. The constructor is automatically invoked whenever an object class is created. It constructs the values of data members while initializing the class.
7. What is Jagged Arrays?
--> The array which has elements of type array is called jagged array. The elements can be of different dimensions and sizes. We can also call jagged array as Array of arrays.
8. What is the difference between ref & out parameters?
--> An argument passed as ref must be initialized before passing to the method whereas out parameter needs not to be initialized before passing to a method.
9. What is the use of using statement in C#?
--> The using block is used to obtain a resource and use it and then automatically dispose of when the execution of block completed.
10. What is serialization?
--> When we want to transport an object through network then we have to convert the object into a stream of bytes. The process of converting an object into a stream of bytes is called Serialization. For an object to be serializable, it should inherit ISerialize Interface.
De-serialization is the reverse process of creating an object from a stream of bytes.
Also Read: PHP Interview Questions and Answers for freshers
11. Can “this” be used within a static method?
--> We can’t use ‘This’ in a static method because we can only use static variables/methods in a static method.
12. What is difference between constants and read-only?
--> Constant variables are declared and initialized at compile time. The value can’t be changed after wards. Read-only variables will be initialized only from the Static constructor of the class. Read only is used only when we want to assign the value at run time.
13. What is an interface class?
--> Interface is an abstract class which has only public abstract methods and the methods only have the declaration and not the definition. These abstract methods must be implemented in the inherited classes.
14. What are value types and reference types?
--> Value types are stored in the Stack whereas reference types stored on heap.
Value types:
[csharp] int, enum , byte, decimal, double, float, long[/csharp]
Reference Types:
[csharp] string , class, interface, object.[/csharp]
15. What are Custom Control and User Control?
--> Custom Controls are controls generated as compiled code (Dlls), those are easier to use and can be added to toolbox. Developers can drag and drop controls to their web forms. Attributes can be set at design time. We can easily add custom controls to Multiple Applications (If Shared Dlls), If they are private then we can copy to dll to bin directory of web application and then add reference and can use them.
User Controls are very much similar to ASP include files, and are easy to create. User controls can’t be placed in the toolbox and dragged – dropped from it. They have their design and code behind. The file extension for user controls is ascx.
Also Read: OOPs Interview Questions and Answers for Fresher
16. What are sealed classes in C#?
--> We create sealed classes when we want to restrict the class to be inherited. Sealed modifier used to prevent derivation from a class. If we forcefully specify a sealed class as base class then a compile-time error occurs.
17. What is method overloading?
--> Method overloading is creating multiple methods with the same name with unique signatures in the same class. When we compile, the compiler uses overload resolution to determine the specific method to be invoke.
18. What is the difference between Array and Arraylist?
--> In an array, we can have items of the same type only. The size of the array is fixed. An arraylist is similar to an array but it doesn’t have a fixed size.
19. Can a private virtual method be overridden?
--> No, because they are not accessible outside the class.
20. Describe the accessibility modifier “protected internal”.
--> Protected Internal variables/methods are accessible within the same assembly and also from the classes that are derived from this parent class.
21. What are the differences between System.String and System.Text.StringBuilder classes?
--> System.String is immutable. When we modify the value of a string variable then a new memory is allocated to the new value and the previous memory allocation released. System.StringBuilder was designed to have concept of a mutable string where a variety of operations can be performed without allocation separate memory location for the modified string.
22. What’s the difference between the System.Array.CopyTo() and System.Array.Clone() ?
--> Using Clone() method, we creates a new array object containing all the elements in the original array and using CopyTo() method, all the elements of existing array copies into another existing array. Both the methods perform a shallow copy.
23. How can we sort the elements of the array in descending order?
--> Using Sort() methods followed by Reverse() method.
24. Write down the C# syntax to catch exception?
--> To catch an exception, we use try catch blocks. Catch block can have parameter of system.Exception type.
Eg:
[csharp]
try
{
GetAllData();
}
catch(Exception ex)
{
}[/csharp]
In the above example, we can omit the parameter from catch statement.
25. What’s the difference between an interface and abstract class?
--> Interfaces have all the methods having only declaration but no definition. In an abstract class, we can have some concrete methods. In an interface class, all the methods are public. An abstract class may have private methods.
26. What is the difference between Finalize() and Dispose() methods?
--> Dispose() is called when we want for an object to release any unmanaged resources with them. On the other hand Finalize() is used for the same purpose but it doesn’t assure the garbage collection of an object.
27. What are circular references?
--> Circular reference is situation in which two or more resources are interdependent on each other causes the lock condition and make the resources unusable.
28. What are generics in C#.NET?
--> Generics are used to make reusable code classes to decrease the code redundancy, increase type safety and performance. Using generics, we can create collection classes. To create generic collection, System.Collections.Generic namespace should be used instead of classes such as ArrayList in the System.Collections namespace. Generics promotes the usage of parameterized types.
29. What is an object pool in .NET?
--> An object pool is a container having objects ready to be used. It tracks the object that is currently in use, total number of objects in the pool. This reduces the overhead of creating and re-creating objects.
30. List down the commonly used types of exceptions in .Net?
--> ArgumentException, ArgumentNullException , ArgumentOutOfRangeException, ArithmeticException, DivideByZeroException ,OverflowException , IndexOutOfRangeException ,InvalidCastException ,InvalidOperationException , IOEndOfStreamException , NullReferenceException , OutOfMemoryException , StackOverflowException etc.
31. What are Custom Exceptions?
--> Sometimes there are some errors that need to be handeled as per user requirements. Custom exceptions are used for them and are used defined exceptions.
32. What are delegates?
--> Delegates are same are function pointers in C++ but the only difference is that they are type safe unlike function pointers. Delegates are required because they can be used to write much more generic type safe functions.
33. How do you inherit a class into other class in C#?
--> Colon is used as inheritance operator in C#. Just place a colon and then the class name.
[csharp] public class DerivedClass : BaseClass[/csharp]
34. What is the base class in .net from which all the classes are derived from?
--> [csharp]System.Object[/csharp]
35. What is the difference between method overriding and method overloading?
--> In method overriding, we change the method definition in the derived class that changes the method behavior. Method overloading is creating a method with the same name within the same class having different signatures.
36. What are the different ways a method can be overloaded?
--> Methods can be overloaded using different data types for parameter, different order of parameters, and different number of parameters.
37. Why can’t you specify the accessibility modifier for methods inside the interface?
--> In an interface, we have virtual methods that do not have method definition. All the methods are there to be overridden in the derived class. That’s why they all are public.
38. How can we set class to be inherited, but prevent the method from being over-ridden?
--> Declare the class as public and make the method sealed to prevent it from being overridden.
39. What happens if the inherited interfaces have conflicting method names?
--> Implement is up to you as the method is inside your own class. There might be problem when the methods from different interfaces expect different data, but as far as compiler cares you’re okay.
40. What is the difference between a Struct and a Class?
--> Structs are value-type variables and classes are reference types. Structs stored on the stack, causes additional overhead but faster retrieval. Structs cannot be inherited.
41. How to use nullable types in .Net?
--> Value types can take either their normal values or a null value. Such types are called nullable types.
[csharp]Int? someID = null;
If(someID.HasVAlue)
{
}
[/csharp]
42. How we can create an array with non-default values?
--> We can create an array with non-default values using Enumerable.Repeat.
43. What is difference between is and as operators in c#?
--> “is” operator is used to check the compatibility of an object with a given type and it returns the result as Boolean.
“as” operator is used for casting of object to a type or a class.
44. What’s a multicast delegate?
--> A delegate having multiple handlers assigned to it is called multicast delegate. Each handler is assigned to a method.
45. What are indexers in C# .NET?
--> Indexers are known as smart arrays in C#. It allows the instances of a class to be indexed in the same way as array.
Eg:
[csharp]public int this[int index] // Indexer declaration[/csharp]
46. What is difference between the “throw” and “throw ex” in .NET?
--> “Throw” statement preserves original error stack whereas “throw ex” have the stack trace from their throw point. It is always advised to use “throw” because it provides more accurate error information.
47. What are C# attributes and its significance?
--> C# provides developers a way to define declarative tags on certain entities eg. Class, method etc. are called attributes. The attribute’s information can be retrieved at runtime using Reflection.
48. How to implement singleton design pattern in C#?
--> In singleton pattern, a class can only have one instance and provides access point to it globally.
Eg:
[csharp]
Public sealed class Singleton
{
Private static readonly Singleton _instance = new Singleton();
}
[/csharp]
49. What is the difference between directcast and ctype?
--> DirectCast is used to convert the type of an object that requires the run-time type to be the same as the specified type in DirectCast.
Ctype is used for conversion where the conversion is defined between the expression and the type.
50. Is C# code is managed or unmanaged code?
--> C# is managed code because Common language runtime can compile C# code to Intermediate language.
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