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Java Programming

Java:

Java is an object-oriented, cross platform, multi-purpose programming language .

Hello world Program:

package Example;

public class Example {

public static void main(String[] args) {

System.out.println("Hello World");

}

Output:

Hello World

Addition Two Numbers:

package Example1;

public class Example1 {

public static void main(String[] args) {
int a,b,c;
a=10;
b=5;
c=a+b;

System.out.println("The value of c is " +c);
}

}

Output:

The value of c is 15

Get Runtime Input:

It has two types
1.Scanner 2.Data Input stream

Scanner

Steps for scanner:
1. Should be give header package
import java.util.*;
2.Declare the Scanner
Scanner add(Variable Name)= new Scanner(System.in);//Input
3.Declare Variable Type
a(Variable)=add(variable name).nextInt();//Variable type

package Example2;
import java.util.*;

public class Example2 {

public static void main(String[] args) {
int a,b,c;
Scanner add=new Scanner(System.in);
a=add.nextInt();
b=add.nextInt();
c=a+b;

System.out.println("The value of c is " +c);
}

}

output:

10
5
The value of c is 15

)

Data Input Stream

Steps for scanner:
1. Should be give header package
import java.io.*;
2.Declare the DataInputStream
DataInputStream add(Variable Name)= new DataInputStream(System.in);//Input
3.Declare Variable Type
a(Variable)=.parseInt(add(variable name).readLine());//Variable type

Integer Variables:
package Example3;
import java.io.*;

public class Example3{

public static void main(String[] args) throws IOException{
int a,b,c;
DataInputStream add=new DataInputStream(System.in);
a=Integer.parseInt(add.readLine());
b=Integer.parseInt(add.readLine());
c=a+b;

System.out.println("The value of c is " +c);
}

}

Output:

10
20
The value of c is 30

Double Variables:

package Example3;
import java.io.*;

public class Example3{

public static void main(String[] args) throws IOException{
Double a,b,c;
DataInputStream add=new DataInputStream(System.in);
a=Double.parseDouble(add.readLine());
b=Double.parseDouble(add.readLine());
c=a+b;

System.out.println("The value of c is " +c);
}

}

Output:
10.5
20.3
The value of c is 30.8

String:

import java.io.*;

public class Example3{

public static void main(String[] args) throws IOException{
String a;
DataInputStream add=new DataInputStream(System.in);
a=add.readLine();

System.out.println("The Name is " +a);
}

}

Output

Sabari
The Name is Sabari

Conditional Statements

1.if-else

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{
int a,b,c;
DataInputStream add=new DataInputStream(System.in);
a=Integer.parseInt(add.readLine());
b=Integer.parseInt(add.readLine());
if(a>b)
{
System.out.println("a is big");
}

else
{
System.out.println("b is big");
}

}

}

Output

b is big

Odd or Even Program (if-else)

package s;
import java.io.*;

public class s {

public static void main(String[] args) throws IOException{
int a,b,c;
DataInputStream add=new DataInputStream(System.in);
a=Integer.parseInt(add.readLine());

if(a%2==0)
{
System.out.println("a is even");
}

else
{
System.out.println("a is odd");
}

}

}

Output

a is odd

a is even

Positive or Negative (if-else)

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int a,b,c;

DataInputStream add=new DataInputStream(System.in);

a=Integer.parseInt(add.readLine());

if(a>0)

{

System.out.println("a is positive");

}

else

{

System.out.println("a is negative");

}

Output

-3

a is negative

If-else if

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int a,b,c;

DataInputStream add=new DataInputStream(System.in);

a=Integer.parseInt(add.readLine());

b=Integer.parseInt(add.readLine());

c=Integer.parseInt(add.readLine());

if(a>b && a>b)

{

System.out.println("a is big");

}

else if(b>a && b>c)

{

System.out.println("b is big");

}

else

{

System.out.println("c is big");

}

Ouput

b is big

Switch-Case

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int n;

DataInputStream add=new DataInputStream(System.in);

n=Integer.parseInt(add.readLine());

switch(n)

{

case 1:

System.out.print("one");

break;

case 2:

System.out.print("two");

break;

default:

System.out.print("more then two");

}

Output

one

Looping Statements

For Loop

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i;

for(i=0;i<5;i++)

{

System.out.println("Welcome");

}

Output

Welcome

While Loop

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i;

i=0;

while(i<5)

{

System.out.println("Welcome");

i++;

}

Output

Welcome

Do-While

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i;

i=0;

{

System.out.println("Welcome");

i++;

}while(i<5);

}

Output

Welcome

For Example Programs

1.Print 1 to 100 numbers

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i;

for(i=1;i<=100;i++)

{

System.out.println(i);

}

Output

1 to 100 numbers will print

2.Print the 9 divisible numbers in 1 to 100

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i;

for(i=9;i<=100;i=i+9)

{

System.out.println(i);

}

Output

3.Print odd numbers 1 to 100

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i;

for(i=1;i<=100;i=i+2)

{

System.out.println(i);

}

Output

1 to 100 odd number will printed

4.Factorial

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i,n,fact=1;

DataInputStream ds=new DataInputStream(System.in);

n=Integer.parseInt(ds.readLine());

for(i=1;i<=n;i++)

{

fact=fact*i;

}

System.out.println("fact is "+fact);

}

Output

fact is 120

5.Prime Number

package s;

import java.io.*;

public class s {

public static void main(String[] args) throws IOException{

int i,n,prime=1;

DataInputStream ds=new DataInputStream(System.in);

n=Integer.parseInt(ds.readLine());

for(i=2;i<n;i++)

{

if(n%i==0)

{

prime=0;

break;

}

if(prime==1)

System.out.println("prime number");

else

System.out.println("not prime number");

}

Output

prime number

6.Pattern Programs - * pattern

import java.io.*;

public class s {

public static void main(String[] args) {

int i,j;

for(i=1;i<6;i++)

{

for(j=1;j<=i;j++)

{

System.out.print("*\t");

}

System.out.println();

}

Output:

* *

* * *

* * * *

* * * * *

Z Pattern

import java.io.*;

public class s {

public static void main(String[] args) {

int i,j;

for(i=1;i<6;i++)

{

for(j=1;j<=i;j++)

{

System.out.print("z\t");

}

System.out.println();

}

Output:

z z

z z z

z z z z

z z z z z

Continuous Number Pattern

import java.io.*;

public class s {

public static void main(String[] args) {

int i,j;

for(i=1;i<6;i++)

{

for(j=1;j<=i;j++)

{

System.out.print(i);

}

System.out.println();

}

Output:

333

4444

55555

While Loop Examples

import java.util.*;

public class s {

public static void main(String[] args) {

int i,a,n;

Scanner sc = new Scanner(System.in);

n=sc.nextInt();

while(n!=0)

{

a=n%10;

System.out.print(a);

n=n/10;

}

Output:

Arrays:

Is a Collection of different datatypes.

It has three types

1.single dimensional array

2.Two dimensional array

3.Multi dimensional array

Example:

1.single Dimensional array

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[]=new int[5];

Scanner sc=new Scanner(System.in);

for(int i=0;i<a.length;i++)

{

a[i]=sc.nextInt();

}

System.out.println("the numbers are");

for(int i=0;i<a.length;i++)

{

System.out.println(a[i]);

}

Output

the numbers are

Single dimensional Example Programs

Find the Negative number in a Array

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[]= {23,-33,55,99};

Scanner sc=new Scanner(System.in);

System.out.println("the negative numbers are");

for(int i=0;i<a.length;i++)

{

if(a[i]<0)

System.out.println(a[i]);

}

Output

the negative numbers are

-33

2.odd array

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[]= {23,-33,52,99};

Scanner sc=new Scanner(System.in);

System.out.println("the negative numbers are");

for(int i=0;i<a.length;i++)

{

if(a[i]%2!=0)

System.out.println(a[i]);

}

Output

the negative numbers are

-33

3.Even Array

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[]= {23,-33,52,99};

Scanner sc=new Scanner(System.in);

System.out.println("the negative numbers are");

for(int i=0;i<a.length;i++)

{

if(a[i]%2==0)

System.out.println(a[i]);

}

Output

the negative numbers are

4.Find the divisible by 9 numbers in a Array

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[]= {18,-33,52,99};

Scanner sc=new Scanner(System.in);

System.out.println("the negative numbers are");

for(int i=0;i<a.length;i++)

{

if(a[i]%9==0)

System.out.println(a[i]);

}

Output

18
99

6.Ascending Order

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[]= {21,12,2,99};

Scanner sc=new Scanner(System.in);

Arrays.sort(a);

System.out.println("the Ascending order");

for(int i=0;i<a.length;i++)

{

System.out.println(a[i]);

}

Output

the Ascending order

2.Two Dimensional Arrays

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[][]=new int[3][3];

Scanner sc=new Scanner(System.in);

for(int i=0;i<3;i++)

{

for(int j=0;j<3;j++)

{

a[i][j]=sc.nextInt();

}

System.out.println("the numbers are");

for(int i=0;i<3;i++)

{

for(int j=0;j<3;j++)

{

System.out.println(a[i][j]);

}

System.out.println("print matrix format");

for(int i=0;i<3;i++)

{

for(int j=0;j<3;j++)

{

System.out.print(a[i][j]+"\t");

}

System.out.println("");

}

Output

the numbers are

print matrix format

1 2 3

4 5 6

7 8 9

3.Multi dimenstional Arrays

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

int a[][][]=new int[2][2][2];

Scanner sc=new Scanner(System.in);

for(int i=0;i<2;i++)

{

for(int j=0;j<2;j++)

{

for(int k=0;k<2;k++)

{

a[i][j][k]=sc.nextInt();

}

System.out.println("the numbers are");

for(int i=0;i<2;i++)

{

for(int j=0;j<2;j++)

{

for(int k=0;k<2;k++)

{

System.out.println(a[i][j][k]);

}

Output

the numbers are

Exceptions:

Runtime error is called Exception

it has three types

Runtime Exception
Compile time exception
User defined exception

Parts of Exceptions:

try
catch
throw
throws
finally

Runtime Exceptions:

Arithmetic exception
ArrayIndexOutofBounds Exception
NegativeArraySize Exception
InputMissMatch Exception
NumberFormatException
NullPointer Exception

Arithmetic exception

The mathematical error is called arithmetic exception.

Example:

import java.util.*;

public class s {

public static void main(String[] args) {

int a, b, c;

a=10;

b=0;

try {

c=a/b;

System.out.print(c);

}

catch(Exception e) {

System.out.println(e);

}

Output:

java.lang.ArithmeticException: / by zero

ArrayIndexOutofBounds Exception

The array size is bigger than given size

Example:

public class s {

public static void main(String[] args) {

try {

int a[]=new int[5];

System.out.println(a[6]);

}

catch(Exception e) {

System.out.println(e);

}

Output:

java.lang.ArrayIndexOutOfBoundsException: 6

NegativeArraySize Exception:

The should not be negative value.

Example:

public class s {

public static void main(String[] args) {

try {

int a[]=new int[-5];

System.out.println(a[6]);

}

catch(Exception e) {

System.out.println(e);

}

Output:

java.lang.NegativeArraySizeException

InputMissMatch Exception:

The input is miss match with given data type.

import java.util.*;

public class s {

public static void main(String[] args) {

try {

int a;

Scanner sc= new Scanner(System.in);

a=sc.nextInt();

}

catch(Exception e) {

System.out.println(e);

}

Output:

name

java.util.InputMismatchException

NumberFormatException:

Count the number of given string value.

import java.util.*;

public class s {

public static void main(String[] args) {

try {

String a= "hello";

int b=Integer.parseInt(a);

}

catch(Exception e) {

System.out.println(e);

}

Output:

java.lang.NumberFormatException: For input string: "hello"

NullPointer Exception:

When the value or input is null

Example:

import java.util.*;

public class s {

public static void main(String[] args) {

try {

String a= null;

System.out.println(a.length());

}

catch(Exception e) {

System.out.println(e);

}

Output:

java.lang.NullPointerException

Finally

Before the Exception Finally Printed

package s;

import java.util.*;

public class s {

public static void main(String[] args) {

try {

String a= null;

System.out.println(a.length());

}

finally {

System.out.println("before the error it will be print");

}

Output

before the error it will be print

Exception in thread "main" java.lang.NullPointerException

at s.s.main(s.java:12)

Compile Time Exceptions

1.IOException

import java.io.*;

public class Example3{

public static void main(String[] args) throws IOException{

String a;

DataInputStream add=new DataInputStream(System.in);

a=add.readLine();

System.out.println("The Name is " +a);

}

Output

Sabari

2.InterruptedException

import java.io.*;

public class Example3{

public static void main(String[] args)throws InterruptedException{

for(int i=0;i<5;i++)
{
Thread.sleep(1000);
System.out.println("hai");
}

}

}

Output

hai

3.SQLException

package s;

import java.sql.*;

public class s {

public static void main(String[] args){

try{

Class.forName("com.mysql.jdbc.Driver");

Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/ex","root","");

}catch(Exception e){ System.out.println(e);}

}

Throw Example

package s;

import java.sql.*;

public class s {

static void get(int a)

{

if(a<18)

throw new ArithmeticException("not eligible for vote");

else

System.out.println("eligble for vote");

}

public static void main(String[] args){

get(5);

}

Output

Exception in thread "main" java.lang.ArithmeticException: not eligible for vote

at s.s.get(s.java:10)

at s.s.main(s.java:16)

3.Userdefined Exception

class JavaException{

public static void main(String args[]){

try{

throw new MyException(2);

// throw is used to create a new exception and throw it.

}

catch(MyException e){

System.out.println(e) ;

}

class MyException extends Exception{

int a;

MyException(int b) {

a=b;

}

public String toString(){

return ("Exception Number = "+a) ;

}

Output

Exception Number = 2

String Functions in Java

String is im muttable in java

1.String Length

package s;

public class s {

public static void main(String[] args){

String a="hejex";

System.out.println(a.length());

}

Output

2.String Concat

package s;

public class s {

public static void main(String[] args){

String a="hello";

String b="world";

System.out.println(a.concat(b));

}

Output

helloworld

3.String UpperCase

package s;

public class s {

public static void main(String[] args){

String a="hello";

System.out.println(a.toUpperCase());

}

Output

HELLO

4.String LowerCase

package s;

public class s {

public static void main(String[] args){

String a="HELLO";

System.out.println(a.toLowerCase());

}

Output

hello

5.CharAt(Find the Character in a Word)

package s;

public class s {

public static void main(String[] args){

String a="hello";

System.out.println(a.charAt(0));

}

Output

6.IndexOf(Find the Letter in a Number)

package s;

public class s {

public static void main(String[] args){

String a="hello";

System.out.println(a.indexOf('e'));

}

Output

7.lastIndexOf(Find the Last letter in Continous Letter)

package s;

public class s {

public static void main(String[] args){

String a="hello";

System.out.println(a.lastIndexOf('l'));

}

Output

8.Trim(To Remove the Space in the word)

package s;

public class s {

public static void main(String[] args){

String a=" hello";

System.out.println(a.trim());

}

Output

hello

9.Equals

package s;

public class s {

public static void main(String[] args){

String a="hello";

String b="hello";

if(a.equals(b))

{

System.out.println("both are same");

}

else

{

System.out.println("not same");

}

Output

both are same

10.EqualsIgnoreCase

package s;

public class s {

public static void main(String[] args){

String a="hello";

String b="HELLO";

if(a.equalsIgnoreCase(b))

{

System.out.println("both are same");

}

else

{

System.out.println("not same");

}

Output

both are same

11.Replace

public class s {

public static void main(String[] args){

String a="hello";

a=a.replace('e','a');

System.out.println(a);

}

Output

hallo

12.Contains

package s;

public class s {

public static void main(String[] args){

String a="This is hello World Program";

if(a.contains("this"))

{

System.out.println("found");

}

else

{

System.out.println("not found");

}

Output

found

13.IsEmpty

package s;

public class s {

public static void main(String[] args){

String a="This is hello World Program";

if(a.isEmpty())

{

System.out.println("yes");

}

else

{

System.out.println("not empty");

}

Output

not empty

14.startsWith

package s;

public class s {

public static void main(String[] args){

String a="This is hello World Program";

if(a.startsWith("This"))

{

System.out.println("yes");

}

else

{

System.out.println("no");

}

Output

yes

15.endsWith

package s;

public class s {

public static void main(String[] args){

String a="This is hello World Program";

if(a.endsWith("This"))

{

System.out.println("yes");

}

else

{

System.out.println("no");

}

Output

STRING BUFFER AND STRING BUILDERS

String buffer and builders are muttable

String buffer

package s;

public class s {

public static void main(String[] args){

StringBuffer s=new StringBuffer("hello");

s.append("world");

System.out.println(s);

}

Output

helloworld

String Builder

package s;

public class s {

public static void main(String[] args){

StringBuilder s=new StringBuilder("hello");

s.append("world");

System.out.println(s);

}

Output

helloworld

OOPS in java

Object-oriented programming:

OOPs Concepts:

1.Class and Objects Example

package s;
class A
{
void get()
{
System.out.println("hai");
}
}

public class s {

public static void main(String[] args){

A ob=new A();
ob.get();
}

}

Output

hai

2.Class and Objects with Parameters Example

package s;
class A
{
void get(int a)
{
System.out.println(a);
}
}

public class s {

public static void main(String[] args){

A ob=new A();
ob.get(5);
}

}

Output
5

3.Constructor

Constructor is a Special Methods

Rules of Constructor

Constructor(s) of a class must has same name as the class name in which it resides.
A constructor in Java can not be abstract, final, static and Synchronized.
Access modifiers can be used in constructor declaration to control its access i.e which other class can call the constructor.

No-argument constructor

package s;
class A
{
A()
{
System.out.println("hai");
}
}

public class s {

public static void main(String[] args){

A ob=new A();

}

}

Output

hai

Parameterized Constructor

package s;
class A
{
A(int a)
{
System.out.println(a);
}
}

public class s {

public static void main(String[] args){

A ob=new A(5);

}

}

Output

4.Polymorphism

Polymorphism in Java is a concept by which we can perform a single action in different ways. Polymorphism is derived from 2 Greek words: poly and morphs. The word "poly" means many and "morphs" means forms. So polymorphism means many forms.

There are two types of polymorphism in Java: compile-time polymorphism and runtime polymorphism. We can perform polymorphism in java by method overloading and method overriding.

If you overload a static method in Java, it is the example of compile time polymorphism. Here, we will focus on runtime polymorphism in java.

Compile time Polymorphism

1.Method Overloading

Same method name but different parameters

package s;
class A
{
void get()
{
System.out.println("hai");
}
void get(int a)
{
System.out.println(a);
}
}

public class s {

public static void main(String[] args){

A ob=new A();
ob.get();
ob.get(5);
}

}

Output

hai
5

2.Constrctor Overloading

Same constructor name but different parameters

package s;
class A
{
A()
{
System.out.println("hai");
}
A(int a)
{
System.out.println(a);
}
}

public class s {

public static void main(String[] args){

A ob=new A();
A ob=new A(5);
}

}

Output

hai
5

Run time Polymorphism

Super class and sub class have same method name and parameter called as Run time polymorphism

Method Overriding

Example

package s;
class A
{
void get()
{
System.out.println("hai");
}
}

class B
{
void get()
{
System.out.println("welcome");
}
}

public class s {

public static void main(String[] args){

B ob=new B();
ob.get();
}

}

Output

welcome

Super Keyword

to avoid method over riding we added super keyword.super is a keyword always points the super class...

Example

package s;
class A
{
void get()
{
System.out.println("hai");
}
}

class B
{
void get()
{
super.get();//its points the super class
System.out.println("welcome");
}
}

public class s {

public static void main(String[] args){

B ob=new B();
ob.get();
}

}

Output

hai
welcome

Inheritance:

Properties of one class can be access by another class.
Code re usability.
Example:

1.single inheritance

package s;
class A //Super class or base class
{
void get()
{

System.out.println("hai");
}
}

class B extends A //Sub class or Derived class

{

void get1()
{
System.out.println("welcome");
}

}

class s
{
public static void main(String args[])
{
B ob=new B();
ob.get();
ob.get1();
}

}

Output

hai
welcome

2.Multilevel inheritance

Example:

package s;
class A //Super class or base class
{
void get()
{

System.out.println("hai");
}
}

class B extends A //Sub class or Derived class

{

void get1()
{
System.out.println("welcome");
}

}

class C extends B
{
void display()
{
System.out.println("Hello");
}

}

class s{
public static void main(String args[])
{
C ob=new C();
ob.get();
ob.get1();
ob.display();

}
}

Ouput

hai
welcome

Hello

Interface:
Instead of Multiple inheritance.
Steps for interface:

Interface A { } //Instead of class and class name
Method should be declared but do not define it.

interface A{
void get();
}

Method should be given in public

public void get()

Implements instead of extends

interface B implements A

Example:

interface A
{
public void get();
}
class B implements A
{
public void get()
{
System.out.println("hai");
}
}
class JavaApplication11
{
public static void main(String[] args) {
B ob=new B();
ob.get();
}
}

Output:

hai

Thread:
Is a small unit of program.

Multithreading:
Group of threads

Life cycle of threads:

New stage - thread starts with start () method
Runnable stage
Running stage - run() method is used to run a thread
Terminated stage - Stop a thread by using stop() method

Types of thread:

extends thread (Inheritance)
implements thread(interface)

Example for extends thread:

class A extends Thread //runnable stage

{

public void run()

{

System.out.println("run stage");

}

class s{

public static void main(String args[])

{

A ob=new A();

ob.start(); //new stage

}

Output:

run stage

Example for implements thread:

class A implements Runnable

{

public void run()

{

System.out.println("hai");

}

class JavaApplication11

{

public static void main(String[] args) {

A ob=new A();

Thread t = new Thread(ob);

t.start();

}

Output:

hai

Example 2:
class A implements Runnable
{
public void run()
{
for(int i=0;i<5;i++)
{
try{
Thread .sleep(1000);
System.out.println("run stage");
}
catch(InterruptedException e){
System.out.println("e");

}
}
}
}

class JavaApplication11
{
public static void main(String[] args) {
A ob=new A();
Thread t = new Thread(ob);
t.start();
}

}

Output:

run stage
run stage
run stage
run stage

run stage // It will take time to print the line.

Priority:

Collections in java

1. ArrayList class

int a[]=new int[5];

System.out.println(a[6])

ArrayIndexOutOfBoundsException

Dynamic array store

Java ArrayList class uses a dynamic array for storing the elements.

1. Java ArrayList class can contain duplicate elements.

Input

Sabari

Saran

Sabari

Output

Sabari

Saran

Sabari

2.Java ArrayList class maintains insertion order.

Input

Sabari

Saran

Output

Sabari

Saran

3.Java ArrayList class is non synchronized.

4.Java ArrayList allows random access because array works at the index basis.

Package import

import java.util.*;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

ArrayList<String> al=new ArrayList<String>();//Creating arraylist

al.add("Ravi");//Adding object in arraylist

al.add("Vijay");

al.add("Ravi");

System.out.println(al);

}

Output

[Ravi, Vijay, Ravi]

For each

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

ArrayList<String> al=new ArrayList<String>();//Creating arraylist

al.add("Ravi");//Adding object in arraylist

al.add("Vijay");

al.add("Ravi");

for(String a:al) //for each loop

{

System.out.println(a);

}

Output

Ravi

Vijay

Ravi

LinkedList

Java LinkedList class uses a doubly linked list to store the elements.

Java LinkedList class can contain duplicate elements.

Java LinkedList class maintains insertion order.

Java LinkedList class is non synchronized.

In Java LinkedList class, manipulation is fast because no shifting needs to occur.

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

LinkedList<String> al=new LinkedList<String>();//Creating arraylist

al.add("Ravi");//Adding object in arraylist

al.add("Vijay");

al.add("Ravi");

for(String a:al) //for each loop

{

System.out.println(a);

}

Output

Ravi

Vijay

List Interface

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

List<String> al=new ArrayList<String>();//list interface

al.add("Ravi");//Adding object in arraylist

al.add("Vijay");

al.add("Ravi");

for(String a:al) //for each loop

{

System.out.println(a);

}

Ouput

Ravi

Vijay

Ravi

Set

HashSet

HashSet class is used to create a collection that uses a hash table for storage

1)HashSet stores the elements by using a mechanism called hashing.

2)HashSet contains unique elements only.

3)HashSet allows null value.

4)HashSet class is non synchronized.

5)HashSet doesn't maintain the insertion order.

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

HashSet<String> al=new HashSet<String>();

al.add("Ravi");//Adding object in arraylist

al.add("Vijay");

al.add("Ravi");

for(String a:al) //for each loop

{

System.out.println(a);

}

Output

Vijay

Ravi

Linked Hashset

Java LinkedHashSet class contains unique elements only like HashSet.

Java LinkedHashSet class provides all optional set operation and permits null elements.

Java LinkedHashSet class is non synchronized.

Java LinkedHashSet class maintains insertion order.

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

LinkedHashSet<String> al=new LinkedHashSet<String>();

al.add("Ravi");//Adding object in arraylist

al.add("Vijay");

al.add("Ravi");

for(String a:al) //for each loop

{

System.out.println(a);

}

Ouput

Ravi

Vijay

TreeSet

Java TreeSet class contains unique elements only like HashSet.

Java TreeSet class access and retrieval times are quiet fast.

Java TreeSet class doesn't allow null element.

Java TreeSet class is non synchronized.

Java TreeSet class maintains ascending order.

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

TreeSet<String> al=new TreeSet<String>();//list interface

al.add("bala");//Adding object in arraylist

al.add("abi");

al.add("cat");

for(String a:al) //for each loop

{

System.out.println(a);

}

Output

Abi

Bala

Cat

Queue

Queue interface orders the element in FIFO(First In First Out) manner. In FIFO, first element is removed first and last element is removed at last.

package s;

import java.util.*; //run time input

class s{

public static void main(String args[])

{

PriorityQueue<String> queue=new PriorityQueue<String>();

queue.add("abc");

queue.add("bcd");

queue.add("efg");

for(String a:queue) //for each loop

{

System.out.println(a);

}

System.out.println("head element "+queue.peek());

queue.poll();//remove

System.out.println("after remove");

for(String a:queue) //for each loop

{

System.out.println(a);

}

Output

abc

bcd

efg

head element abc

after remove

bcd

efg

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