Arik Mukherjee : July 2023

Saturday, July 22, 2023

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');
    }
}

Function Overloading using JAVA ( Method 1 )

public class FunctionOverloading1 {

    void f()
    {
        System.out.println("this is without parameter");
    }
    void f(int x)
    {
        System.out.println("this is integer parameter");
    }
    void f(double x)
    {
        System.out.println("this is double parameter");
    }
    void f(char x)
    {
        System.out.println("this is character parameter");
    }

    public static void main(String[] args) {
        FunctionOverloading1 ob=new FunctionOverloading1();
        ob.f();
        ob.f(5);
        ob.f(10.5);
        ob.f('a');
    }
}

Factorial Program using JAVA

public class Factorial {

    public static void main(String[] args) {
        int i,factorial=1,number=5;
        for(i=1;i<=number;i++)
        {
            factorial=factorial*i;
        }
        System.out.println("Factorial of "+number+" is "+factorial);
    }
}

Constructor Overloading using JAVA

class Constructor

{
    Constructor()
    {
        System.out.println("this is without parameter");
    }
    Constructor(int x)
    {
        System.out.println("this is integer parameter");
    }
    Constructor(float x)
    {
        System.out.println("this is float parameter");
    }
    Constructor(char x)
    {
        System.out.println("this is character parameter");
    }
}
public class ConstructorOverloading {
    public static void main(String[] args) {
        Constructor ob1=new Constructor();
        Constructor ob2=new Constructor(5);
        Constructor ob3=new Constructor(10.2f);
        Constructor ob4=new Constructor('a');
    }
}

JAVA - COMMAND LINE - EXAMPLE 2

public class CommandLine2 {

    public static void main(String[] args) {
        int i,sum=0;
        for (i=0;i<args.length;i++)
        {
            sum=sum+Integer.parseInt(args[i]);
        }
        System.out.println("Sum is="+sum);
    }
}