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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Difference between while and do-while

The while statement verifies the condition before entering into the loop to see whether the next loop iteration should occur or not. The do-while statement executes the first iteration without checking the condition, it verifies the condition after finishing each iteration. The do-while statement will always execute the body of a loop at least once.

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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].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.