this keyword in java

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this keyword in java

this keyword in java

1. Using ‘this’ keyword to refer current class instance variables

//Java code for using 'this' keyword to
//refer current class instance variables
class Test
{
int a;
int b;

// Parameterized constructor
Test(int a, int b)
{
this.a = a;
this.b = b;
}

void display()
{
//Displaying value of variables a and b
System.out.println("a = " + a + " b = " + b);
}

public static void main(String[] args)
{
Test object = new Test(10, 20);
object.display();
}
}
Output:

a = 10 b = 20

2. Using this() to invoke current class constructor

// Java code for using this() to
// invoke current class constructor
class Test
{
int a;
int b;

//Default constructor
Test()
{
this(10, 20);
System.out.println("Inside default constructor n");
}

//Parameterized constructor
Test(int a, int b)
{
this.a = a;
this.b = b;
System.out.println("Inside parameterized constructor");
}

public static void main(String[] args)
{
Test object = new Test();
}
}
Output:

Inside parameterized constructor
Inside default constructor

3. Using ‘this’ keyword to return the current class instance

//Java code for using 'this' keyword
//to return the current class instance
class Test
{
int a;
int b;

//Default constructor
Test()
{
a = 10;
b = 20;
}

//Method that returns current class instance
Test get()
{
return this;
}

//Displaying value of variables a and b
void display()
{
System.out.println("a = " + a + " b = " + b);
}

public static void main(String[] args)
{
Test object = new Test();
object.get().display();
}
}
Output:

a = 10 b = 20

4. Using ‘this’ keyword as method parameter

// Java code for using 'this'
// keyword as method parameter
class Test
{
int a;
int b;

// Default constructor
Test()
{
a = 10;
b = 20;
}

// Method that receives 'this' keyword as parameter
void display(Test obj)
{
System.out.println("a = " +obj.a + " b = " + obj.b);
}

// Method that returns current class instance
void get()
{
display(this);
}

public static void main(String[] args)
{
Test object = new Test();
object.get();
}
}
Output:

a = 10 b = 20

5. Using ‘this’ keyword to invoke current class method

// Java code for using this to invoke current
// class method
class Test {

void display()
{
// calling function show()
this.show();

System.out.println("Inside display function");
}

void show() {
System.out.println("Inside show funcion");
}

public static void main(String args[]) {
Test t1 = new Test();
t1.display();
}
}
Output :

Inside show funcion
Inside display function

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

// Java code for using this as an argument in constructor
// call
// Class with object of Class B as its data member
class A
{
B obj;

// Parameterized constructor with object of B
// as a parameter
A(B obj)
{
this.obj = obj;

// calling display method of class B
obj.display();
}

}

class B
{
int x = 5;

// Default Constructor that create a object of A
// with passing this as an argument in the
// constructor
B()
{
A obj = new A(this);
}

// method to show value of x
void display()
{
System.out.println("Value of x in Class B : " + x);
}

public static void main(String[] args) {
B obj = new B();
}
}
Output :

Value of x in Class B : 5

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