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How to implement Singleton
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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 |
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 |
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 |
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 |
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 |
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 |
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