Thread class in Java - 1

 Java Thread Programs

1. Dealing with main

class T1Demo

{

public static void main(String args[])

{

Thread t=Thread.currentThread();

System.out.println("current "+t);

System.out.println(t.getName());

t.setName("MyMain");

System.out.println("current now "+t);

System.out.println(t.getName());

try

{

for(int i=0;i<10;i++)

{

System.out.println(i);

Thread.sleep(1000);

}

}

catch(InterruptedException e)

{

System.out.println("caught");

}

}

}

o/p: --------------------------------------------------------------------------------------------

ddmc@ddmc-desktop:~$ java T1Demo

current Thread[main,5,main]

main

current now Thread[MyMain,5,main]

MyMain

0

1

2

3

4

5

6

7

8

9

In [main, 5, main], 5 is the priority of the thread, the last main is the group name of the thread.

Thread class in Java - 2

 2. Creating new thread by implementing Runnable

class NewThread implements Runnable

{

Thread t;

NewThread()

{

//create a new thread

t=new Thread(this,"Demo Thread");

System.out.println("child thread "+t);

t.start();

}

public void run()

{

try

{

for(int i=5;i>0;i--)

{

System.out.println("child "+i);

Thread.sleep(500);

}

}

catch(InterruptedException e)

{

System.out.println("child interrupted");

}

System.out.println("exiting child thread");

}

}

class T2Demo

{

public static void main(String args[])

{

new NewThread();

try

{

for(int i=100;i>95;i--)

{

System.out.println("Main "+i);

Thread.sleep(1000);

}

}

catch(InterruptedException e)

{

System.out.println("main interrupted");

}

System.out.println("exiting main thread");

}

}

o/p: -------------------------------------------------------------------------------------------

ddmc@ddmc-desktop:~$ java T2Demo

child thread Thread[Demo Thread,5,main]

child 5

Main 100

child 4

Main 99

child 3

child 2

Main 98

child 1

exiting child thread

Main 97

Main 96

exiting main thread

--------------------------------------------------------------------------------------------------

Use of ' this ' keyword in Java

 How to use ' this ' keyword in java?

class A

{

    public int x;

    A()

    {

        x=0;

        System.out.println("Default Constructor");

    }

    A(int x)

    {

        this.x=x;

        System.out.println("I am THIS.X");

    }

}

public class UseofThis{

    public static void main(String[] args) {

        A ob1=new A();

        A ob2=new A(5);

    }

}

Use of Scanner Class in Java

SCANNER CLASS: 

Example 1:

import java.util.Scanner;

public class ScannerEg1 {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter a number");

        int a = sc.nextInt();

        double sq = a * a;

        double rem = sq % 10;

        System.out.println("square is" + sq);

        System.out.println("Last Digit is" + rem);

    }

}

Example 2:

import java.util.*;

public class ScannerEg2 {

    public static void main(String[] args) {

        int n, sq, rem;

        Scanner sc = new Scanner(System.in);

        System.out.println("enter a number");

        n = sc.nextInt();

        sq = n * n;

        System.out.println(sq);

        rem = sq % 10;

        System.out.println(rem);

        if (n == rem) {

            System.out.println("equal");

        } else {

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

        }

    }

}

Static function in java

How to call a method in main without creating object in Java ?

public class Staticfunc {

    static void f()          //Static keyword is used as the f() is called in main method without object.

    {

        System.out.println("Sunday");

    }

    public static void main(String[] args) {

        System.out.println("Monday");

        f();

        System.out.println("friday");

    } 

Non-static Function in JAVA

How to call a function in main by creating object in java ?

 public class NonStaticFunc {

    void f()

    {

        System.out.println("Sunday");

    }

    public static void main(String[] args) {

        NonStaticFunc ob=new NonStaticFunc();

        System.out.println("Monday");

        ob.f();

        System.out.println("Friday");

    }

}

// Static keyword is not used here as object is created.//

Function Overloading using JAVA ( Method 2 )

 class Func

{

   void f()

    {

        System.out.println("this is without parameter");

    }

    void f(int x)

    {

        System.out.println("this is integer parameter");

    }

    void f(float x)

    {

        System.out.println("this is float parameter");

    }

    void f(char x)

    {

        System.out.println("this is character parameter");

    }

}

public class FunctionOverloading2 {

    public static void main(String[] args) {

         Func ob=new Func();

         ob.f();

        ob.f(5);

        ob.f(10.5f);

        ob.f('a');

    }

}