How to avoid the creation of object in Java?

Question

I am new to java programming,I have one class,for this class i created two object(obj1,obj2).i don't want to create other than these object,if any body wants to create one more object for this class that should refer to first,or second objects only(instead of creating one more object).how to do this?please refer below code

class B 
{ 
 void mymethod()
     {  
       System.out.println("B class method");
          } 
 }   
class Myclass extends B
{ 
 public static void main(String s[])
     {  
       B  obj1=new B();//this is obj1
       B  obj2=new B();//this is obj1
       B  obj3=new B();//don't allow to create this and refer this to obj1 or obj2
          } 
 }

Thanks azam

Answer 1

Check out the Singleton design pattern.

Answer 2

What you need is the Singleton design pattern.

Class B should look something like so:

class B
{
    private static B instance = null;

    private B()
    {
         //Do any other initialization here
    }

    public static B getInstance()
    {
        if (instance == null)
        {
            instance = new B();
        }
        return instance;
    }
}

Then, in your Myclass, just do this:

B obj1 = B.getInstance();
B obj2 = B.getInstance();

Note: This is not thread safe. If you are looking for a thread safe solution please consult the Wiki Page.

EDIT: You could also have a static initializer

class B
{
    private static B instance = null;
    static
    {
         instance = new B();
    }


    private B()
    {
         //Do any other initialization here
    }

    public static B getInstance()
    {       
        return instance;
    }
}