Suppose i have 3 java classes A , B and C
I need to create an object of class C that is used in both A and B but the problem in creating the object separately is that the constructor of class c is called 2 times. But i want the constructor to be called just once.
So i want to use the object created in class A into class b.
So create the object once, and pass it into the constructors of A and B:
C c = new C();
A a = new A(c);
B b = new B(c);
...
public class A
{
private final C c;
public A(C c)
{
this.c = c;
}
}
Note that this is very common in Java as a form of dependency injection such that objects are told about their collaborators rather than constructing them themselves.
Create object C outside of both A and B and have the constructors of A and B accept an instance of class C.
class A {
public A( C c ) {
....
}
}
class B {
public B( C c ) {
....
}
}
Alternatively, if the constructors for A and B are not called near each other you could define Class c as a singleton. See http://mindprod.com/jgloss/singleton.html
you would then do:
A a = new A(C.getInstance());
B b = new B(C.getInstance());
or alternatively, in constructors for A and B just call getInstance instead of the constructor, ie.
// C c = new C();
C c = C.getInstance();
You want to share an instance? Ok, how about his:
C c = new C();
B b = new B(c);
A a = new A(c);
Another option is:
B b = new B();
A a = new A(b.c);
