JAVA EXAMPLE PROGRAMS

Java Singleton Class Example Using Private Constructor

We can make constructor as private. So that We can not create an object outside of the class.
This property is useful to create singleton class in java.
Singleton pattern helps us to keep only one instance of a class at any time.
The purpose of singleton is to control object creation by keeping private constructor.

Java Singleton Sample Code

Code:

package com.myjava.constructors;

public class MySingleTon {
    
    private static MySingleTon myObj;
    /**
     * Create private constructor
     */
    private MySingleTon(){
        
    }
    /**
     * Create a static method to get instance.
     */
    public static MySingleTon getInstance(){
        if(myObj == null){
            myObj = new MySingleTon();
        }
        return myObj;
    }
    
    public void getSomeThing(){
        // do something here
        System.out.println("I am here....");
    }
    
    public static void main(String a[]){
        MySingleTon st = MySingleTon.getInstance();
        st.getSomeThing();
    }
}

Other Constructor Examples

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What is adapter class?

An adapter class provides the default implementation of all methods in an event listener interface. Adapter classes are very useful when you want to process only few of the events that are handled by a particular event listener interface. You can define a new class by extending one of the adapter classes and implement only those events relevant to you.

Famous Quotations

Discipline is just choosing between what you want now and what you want most.

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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected] or you can comment on the page.

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java is registered trademark of Oracle.