Question

How do I access an object, that was instantiated in the constructor, in another method? (e.g. object b below) What is the best way to instantiate this object so that all of my class methods have access to the same object?

public class ClassA{ 
  private final int size;       

  public ClassA(int N){
      size = N;    
      ClassB b = new ClassB(size);
  }

  public void doSomething(){
      b.doSomething();        
  }      
}

Answer 1

You just need to assign it to a field:

public class ClassA{ 
  private final int size;       
  private final ClassB b;

  public ClassA(int N){
    size = N;    
    b = new ClassB(size);
  }

  public void doSomething(){
    b.doSomething();        
  }      
}