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Java this keyword

What is this keyword?


In Java, the this keyword is a reference variable that refers to the current object. It is primarily used inside methods or constructors of a class to refer to the instance variables or methods of the current object.

Here are some common uses of the this keyword in Java:

1. To refer to instance variables:

 

Example:

class MyClass {
    private int x;

    void setX(int x) {
       this.x = x;          // Use "this" to refer to the instance variable "x"
    }

    void displayX() {
        // Use "this" to refer to the instance variable "x" when displaying its value
        System.out.println("The value of x is: " + this.x);
    }

    public static void main(String[] args) {
        MyClass Obj = new MyClass();

        // Set the value of x using the setX method
        Obj .setX(42);

        // Display the value of x using the displayX method
        Obj .displayX();
    }
}

 

Output:

The value of x is: 42

 

2.  To invoke the current object's method:

 

Example:

class MyClass {
    void myMethod() {
        System.out.println("Inside myMethod");
    }

    void invokeMyMethod() {
        this.myMethod();    // Use "this" to invoke the current object's method
    }

    public static void main(String[] args) {
        MyClass Obj = new MyClass();

        Obj.invokeMyMethod();     // Invoke the method using the invokeMyMethod
    }
}

 

3. To pass the current object as a parameter to other methods or constructors:

 

Example:

public class MyClass {
    private int value;

    public MyClass(int value) {
        // Use "this" to refer to the current object when passing it as a parameter
        initializeValue(this, value);
    }

    public void displayValue() {
        System.out.println("The value is: " + this.value);
    }

    private void initializeValue(MyClass obj, int val) {
        // Use "this" to refer to the current object when assigning values
        obj.value = val;
    }

    public static void main(String[] args) {
        MyClass myObject = new MyClass(42);

        // Display the value using the displayValue method
        myObject.displayValue();
    }
}

 

more about this keyword

The use of this helps disambiguate between instance variables and method parameters, especially when they have the same name. It also allows you to explicitly refer to the members of the current object, making the code more readable and reducing potential confusion.

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