How to implement Singleton

Categories >> Software >> Java Related >> Java J2EE >> Core Java
Suggest New Category

Question Posted / guest

6 Answers
9870 Views
DELL, I also Faced
E-Mail Answers

Answers were Sorted based on User's Feedback

How to implement Singleton..

Answer / hardeep thakur

Here is code to implement the singleton

public class SingletonClass {
private static SingletonClass singleObj ;
private SingletonClass(){}

public static synchronized SingletonClass getInstance()
{
if(singleObj ==null){
singleObj = new SingletonClass();
}
return singleObj;
}

public Object clone() throws CloneNotSupportedException
{
throw new CloneNotSupportedException();
}

}

Is This Answer Correct ?

7 Yes

0 No

How to implement Singleton..

Answer / ajooba

since 1.5 version best way is to use an enum

public enum My
{
instance;
}

Is This Answer Correct ?

1 Yes

0 No

How to implement Singleton..

Answer / supraja

The Singleton pattern
In Design Patterns, the authors describe the Singleton
pattern like this:

Ensure a class has only one instance, and provide a global
point of access to it.

The figure below illustrates the Singleton design pattern
class diagram.

Singleton class diagram

As you can see from the figure above, there's not a whole
lot to the Singleton design pattern. Singletons maintain a
static reference to the sole singleton instance and return
a reference to that instance from a static instance()
method.

Is This Answer Correct ?

0 Yes

0 No

How to implement Singleton..

Answer / dara

Ensure a class has only one instance, and provide a global
point of access to it. Singletons maintain a static
reference to the sole singleton instance and return a
reference to that instance from a static instance() method.

Example:
========

public class MyClassSingleton {

private static MyClassSingleton instance;

//Constructor must be protected or private to perevent
creating new object
protected MyClassSingleton() {

}
//could be synchronized
public static MyClassSingletongetInstance() {
if (instance==null)
instance = new MyClassSingleton()
return instance;

}
public void method1(){
System.out.println("hello singleton");
}
}//end of class

Is This Answer Correct ?

1 Yes

1 No

How to implement Singleton..

Answer / manoj kumar

public class DateUtil implements Serializable,Cloneable {

private static volatile Dateutil instance;

private DateUtil() {
//no-op
}

public static DateUtil getInstance() {

if(instance==null) {
synchronized(DateUtil.this) {
if(instance==null) {
instance = new DateUtil();
}
}
return instance;
}

protected Object readResolve() {
return instance;
}

public Object clone() throws CloneNotSupportedException {

super.clone();

throw new CloneNotSupportedException;
}

Is This Answer Correct ?

0 Yes

0 No

How to implement Singleton..

Answer / shaik baji

Singleton Example:
==================
public class Singleton
{
private static Singleton singleton;

private Singleton()
{
}

public static Singleton getInstance()
{
if(singleton==null)
{
singleton = new Singleton();
return singleton;

}
else
{
return singleton;
}

}

}

Accessing Singleton instance
============================
public class STDemo
{
public static void main(String[] args)
{
Singleton obj1= Singleton.getInstance();
System.out.println(obj1.hashCode());

Singleton obj2= Singleton.getInstance();
System.out.println(obj2.hashCode());

Singleton obj3= Singleton.getInstance();
System.out.println(obj3.hashCode());

}
}

Is This Answer Correct ?

0 Yes

1 No

Post New Answer