Singleton Class in Java

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What is Singleton class in java?

Singleton class is a class of which we can create only one object.

Java program to create Singleton class / Implementing a Singleton class :

public class SingltonClassTest {

private static SingltonClassTest t = new SingltonClassTest();

private SingltonClassTest()

{

//don’t allow to create object

}

public static SingltonClassTest getSingltonClassTest() {

// method id static because object is static

return t;

}

 

public static void main(String[] args) {

SingltonClassTest t1 = SingltonClassTest.getSingltonClassTest();

SingltonClassTest t2 = SingltonClassTest.getSingltonClassTest();

SingltonClassTest t3 = SingltonClassTest.getSingltonClassTest();

System.out.println(“Hashcode of t1==” + t1.hashCode());

System.out.println(“Hashcode of t2==” + t2.hashCode());

System.out.println(“Hashcode of t3==” + t3.hashCode());

}

}

Output:
Hashcode of t1==366712642
Hashcode of t2==366712642
Hashcode of t3==366712642

 

Here same hash code is getting printed for all three objects as it is a Singleton class.

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