this keyword in java

//case 1:-this keyword in java

//differentiate local variable and instance variable if those are declared with same name

package thiskeyword;

public class PrintName {

           

            String fname;

            String mname;

            String lname;

            public PrintName(String fname, String mname, String lname) {

                        super();

                        this.fname = fname;

                        this.mname = mname;

                        this.lname = lname;

            }

           

            public void display()

            {

                        System.out.println("First Name="+fname);

                        System.out.println("Middle Name="+mname);

                        System.out.println("Last Name="+lname);

            }

            public static void main(String[] args) {

                        PrintName pn=new PrintName("Govind", "Ballabh", "khan");

                         pn.display();

             

            }

}

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

First Name=Govind

Middle Name=Ballabh

Last Name=khan

=====================================================================================

//case 2:-this keyword in java

// Using this() to invoke current class constructor

package thiskeyword;

public class PrintNameDemo {

           

            String fname;

            String mname;

            String lname;

           

            public PrintNameDemo()

            {

                        this("Govind","Ballabh","Khan");

            }

           

            public PrintNameDemo(String fname,String mname,String lname)

            {

            this.fname=fname;

            this.mname=mname;

            this.lname=lname;

            }

           

            public void display()

            {

                        System.out.println("First Name="+fname);

                        System.out.println("Middle Name="+mname);

                        System.out.println("Last Name="+lname);

            }

           

            public static void main(String[] args) {

                        PrintNameDemo pnd=new PrintNameDemo();

                        pnd.display();

            }

           

           

}

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

First Name=Govind

Middle Name=Ballabh

Last Name=Khan

========================================================================

//case 3:-this keyword in java

// to return the current class instance

package thiskeyword;

public class ReturnCurrentObject {

           

            String s1;

            String s2;

            public ReturnCurrentObject(String s1, String s2) {

                        super();

                        this.s1 = s1;

                        this.s2 = s2;

            }

           

   ReturnCurrentObject retObject()

            {

                        return this;

                       

            }

  

   public void display()

   {

               System.out.println("s1="+s1);

               System.out.println("s2="+s2);

   }

  

   public static void main(String[] args) {

            ReturnCurrentObject rco=new ReturnCurrentObject("java", "Technology");

    rco.display();

    ReturnCurrentObject kk = rco.retObject();

    kk.display();

   //rco.retObject().display();

   }

}

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

s1=java

s2=Technology

s1=java

s2=Technology

========================================================================================

//case 4:-this keyword in java

// Using ‘this’ keyword as method parameter

package thiskeyword;

public class TestData {

           

            int x;

            int y;

            int z;

            public TestData(int x, int y, int z) {

                        super();

                        this.x = x;

                        this.y = y;

                        this.z = z;

            }

           

            public void display(TestData t)

            {

                        System.out.println("Sum="+(x+y+z));

            }

           

            public void get()

            {

               display(this);

            }

           

            public static void main(String[] args) {

                        TestData td=new TestData(50, 50, 100);

                        td.get();

            }

           

}

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

Sum=200

 =======================================================================================

//case 5:-this keyword in java

// Using ‘this’ keyword to invoke current class method

package thiskeyword;

public class TestCheck {

           

            String s1;

            String s2;

           

            public void getdata(String x,String y)

            {

                        s1=x;

                        s2=y;

                        this.showData();

            }

           

            public void showData()

            {

                        System.out.println("S1="+s1+"S2="+s2);

            }

           

            public static void main(String[] args) {

                        TestCheck tc=new TestCheck();

                        tc.getdata("govind", "khan");

            }

}

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

S1=govindS2=khan

====================================================================================== 

 //case 6:-this keyword in java

 Using ‘this’ keyword as an argument in the constructor call

package thiskeyword;

public class M {

           

            N n;

            public M(N n) {

                       

                        super();

                        this.n = n;

                        n.display();

            }

}

package thiskeyword;

public class N {

            int k=100;

           

            public N() {

                       

                        M m=new M(this);

                       

            }

           

  void display()

    {

        System.out.println("Value of k in Class N : " + k);

    }

    

    public static void main(String[] args) {

        N obj = new N();

}

}

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

//Value of k in Class N : 100