Before Writing Singleton Design pattern you should follow these steps.
#1). create an instance as static and return type as The same class, and it should be assigned as null.
private static Singletonn instance = null;
#2). "Create a Constructor as private" to deny the creation of object from other class.
private Singletonn(){
}#3). Write a static method to create object for our class.It should be Once for a class.
public static Singletonn getInstance(){
}#4). At last return the class Object.
Here We are creating the object once only not again and again.The first time created object is returning again when you called.
package javabynataraj.basic;
class Singletonn {
private static Singletonn instance = null;
private Singletonn(){
}
public static Singletonn getInstance(){
if(instance==null){
instance = new Singletonn();
}
return instance;
}
}
public class Singleton{
public static void main(String[] args) {
System.out.println("before calling ...");
System.out.println(Singletonn.getInstance());
System.out.println("Once Called");
System.out.println(Singletonn.getInstance());
System.out.println("Second time called");
}
}
For Refernce books:
