Overview

In this tutorial, we will learn about this keyword in Java. When used in the instance method or constructor this points to or references the current object. Method or constructor arguments  can shadow the object variables with the same names. We use this to refer the object variables.

Example

package staff;
// www.TestingDocs.com - Java Tutorials
public class Staff {
	private String name;
	private String address;

	//Staff no-arg constructor
	public Staff() {

	}

	//Staff class constructor
	public Staff(String name, String address) {
		this.name = name;
		this.address = address;
	}

}

 

In the Staff class constructor the arguments shadow the instance variables. We use this keyword to reference the object fields.

 

 

Calling overloaded constructors

Another most common use of this keyword is to invoke constructor from another. We can call another constructor of the class using this keyword.

        //Staff constructor
	public Staff(String name) {
       this.name= name;
	}

	//Staff class constructor
	public Staff(String name, String address) {
		this(name);
		this.address = address;
	}

Notice that we have invoked the constructor:

this(name);

Note that the constructor call should be the first statement in the constructor. The below code is INVALID

        //Staff class constructor
	public Staff(String name, String address) {
		this.address = address;
		this(name);
	}

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