This Keyword Example in Java

Introduction

This Keyword is a classic Java console program that demonstrates the concept with complete source code and sample output. Practical numeric and utility programs — primes, factorial, palindrome and similar classics.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

The keyword this is a Java language keyword that represents the current instance of the class in which it appears. It is used to access class variables and methods. Since all instance methods are virtual in Java, this can never be null.

Syntax

this.Variable_name = Variable_name;

This Keyword Example Program

class ClassOne {  
    public void getClassName() {  
        System.out.println("Class : " + this.getClass());  
    }  
}  

class ClassTwo {  
  
    public void getClassName() {  
        System.out.println("Class : " + this.getClass());  
    }  
}  

public class ThisKeywordDemo {  
    public static void main(String args[]) {  
        ClassOne obj1 = new ClassOne();  
        ClassTwo obj2 = new ClassTwo();  
        obj1.getClassName();  
        obj2.getClassName();  
    }  
}

Sample Output

Class : classOne
Class : classTwo

When to use

Use this this keyword example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. A println / print call writes text to the console — part of the sample output below.

3. A println / print call writes text to the console — part of the sample output below.

4. ClassOne obj1 = new ClassOne(); updates a variable used in the calculation or output.

5. ClassTwo obj2 = new ClassTwo(); updates a variable used in the calculation or output.

6. Compare your console output with the sample output for This Keyword to confirm the program behaves correctly.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.