this keyword in java

 this keyword in java refers to current object,

where to use this keyword in java ?

this keyword in java having multiple benefits and usage ,lets see one by one :

1.To Refer Current class instance variables  we can use this keyword in java

Example : 

step 1: firstly create a class Website.java as below 

  	class Website{
		String authorName;
		String websiteUrl;	
			public Website(String authorName, String websiteUrl) {
				this.authorName = authorName;
				this.websiteUrl = websiteUrl;
			}		
			public String getAuthorName() {
				return authorName;
			}
			public void setAuthorName(String authorName) {
				this.authorName = authorName;
			}
			public String getWebsiteUrl() {
				return websiteUrl;
			}
			public void setWebsiteUrl(String websiteUrl) {
				this.websiteUrl = websiteUrl;
			}
			@Override
			public String toString() {
				return "Website [authorName=" + authorName + ", websiteUrl=" + websiteUrl + "]";
		}
	}
  
  Step 2 : create a class WebsiteCreator.java as below :

	public class WebsiteCreator {
		public static void main(String[] args) {
			Website website1 =new Website("Swapnil V","https://www.crtr4u.com");
			Website website2 =new Website("Prashant V","https://www.gymbag4u.com");
			System.out.println("Website Details :");
			System.out.println(website1);
			System.out.println(website2);
		}
	}

When we run above program we will get output as below :

Website Details :
Website [authorName=Swapnil V, websiteUrl=https://www.crtr4u.com]
Website [authorName=Prashant V, websiteUrl=https://www.gymbag4u.com]

Explanation of above program : when we are creating object of Website class by using new keyword as below :

    Website website1 =new Website("Swapnil V","https://www.crtr4u.com");

we are passing name "Swapnil V" and url "https://www.crtr4u.com" as input to the constructor of Website class ,inside Website class constructor we are using this keyword to assign values to instance variables of class as below :

	public Website(String authorName, String websiteUrl) {
		this.authorName = authorName;
		this.websiteUrl = websiteUrl;
	}	

using this keyword we are referring class instance variables inside constructor and setting values which are received.

2.To invoke current class constructor we can use this() in java :

to invoke current class constructor we can use this() in java , it is used for constructor chaining ,lets see the real time use of this() in java :

Example :

create a class AdditionOperations.java as below : with two constructors :

	public class AdditionOperations {	
		int num1,num2,num3;
		public AdditionOperations(int num1,int num2) {
			this.num1=num1;
			this.num2=num2;
		}	
		public AdditionOperations(int num1, int num2, int num3) {
			/*this is constructor chaining
		here we are calling constructor with two arguments using this()*/
		this(num1,num2); 
		this.num3 = num3;
	}
	void add() {
		System.out.println("Addition is "+(this.num1+this.num2+this.num3));
		}
	}

create a class ConstructorChaining.java as below :

 public class ConstructorChaining {
		public static void main(String[] args) {
			AdditionOperations op1=new AdditionOperations(1,2);
			op1.add();
			AdditionOperations op2=new AdditionOperations(4,3,5);
			op2.add();
		}
	}

output of above code is :

Addition is 3 

Addition is 12

3.Calling current class method using this keyword in java:

you can invoke method by using this keyword, note that ,if you don't use this keyword then compiler automatically add this keyword.

Example :

	public class CallConstructor {
		public static void main(String[] args) {
			WellWisher wellWish=new WellWisher();
		}
	}
	class WellWisher{
		WellWisher(){
			System.out.println("welcome to Java");
			this.msgDisplay("called msgDisplay method using this keyword");
		}	
		public void msgDisplay(String message){
			System.out.println(message);
		}	
	}

Thanks a lot for reading our article ,keep programming.