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Java How To Write A Constructor

Writing a constructor in Java is easy. Constructors are used to initialize an instance of a class. They can also be used to handle initial parameters. The constructor for a class has the same name as the class and does not have a return value. If a return value is specified it will not be treated as an actual constructor and will not be called when creating an instance of a class.

The most basic syntax looks like this:

public class MyClass{

Here is an example of a simple constructor that initializes a variable.

import java.util.*;

public class Test1 {
    public int x;

    public Test1(){      // constructor
        x = 1234;        // initialize variable
    public static void main( String[] args ){
        Test1 t = new Test1();
        System.out.println( t.x );

You can also pass a parameter to a constructor like this.

public Test1(int a){     // constructor
    x = a;               // initialize variable

If the parameter has the same name as the class attribute that you want to set you can refer to it using the “this” keyword like this.

public Test1(int x){      // constructor
    this.x = x;           // initialize variable