I have two public classes class A and class B in two different packages.
So when I try to initialize class B inside class A, it throws a null pointer exception. Something like :
public class A {
class B = new class B();
}
Infact I have to initialize it inside a method to use it. Example :
public class A {
public void method(){
class B = new class B();
}
}
I know I am missing something here, but need an urgent help on this
Edit: You should have a constructor
Like:
public class A {
public B theB;
public A(){
this.theB = new B();
}
}
But you can use an implicit one like this:
public class A {
public B theB = new B();
}
You hadn't named your class member variable, hence you were getting strange errors. In fact... I'm surprised it compiled.
class B = new class B(); because you are not assigning it to a variable. Are you perhaps leaving out too many details and obscuring the problem?
You are obscuring/simplifying too much for me to be sure, but in order to initialize a class don't forget it still is a variable.
public class A {
public classB nameForB = new classB();
//class A methods
}
Or if you want B to only be initialized upon the initialization of A (which is safer imo)
public class A {
public classB nameForB;
public A(){
nameForB = new classB();
}
//class A methods
nameForB is an instance variable in both cases, both of your approaches would not initialize/instantiate that variable until an instance of A is created. There should be no difference. Like you said though, OP has changed their example code too much for us to be able to know what the actual problem is.