CODEWITHSUNDEEP
java
runios
runios

Reputation: 394

Accessing Inner Class of a object from a different object

I have class A, class B and class C.

class B is an inner class of class A. As shown below:

public class A {

       public class B {
            String day;
            HashMap<String, ArrayList<Date>> locationTimes;
            public B() { 
                locationTimes = new HashMap<String, ArrayList<Date>>();}
            }

      **B fieldB;**

   .....
  }

Using dependency injection(may not be relevant to the problem), I inject the object of class A into class C.

I am now trying to access the fields (String day, HashMap locationTimes) within class B, from a different object of class C. But I am unable to do so.

Any help is appreciated.

Upvotes: 1

Views: 1454

Answers (3)

Dimitrios Begnis
Dimitrios Begnis

Reputation: 813

You have to create an instance of B like:

public class A {

   private B b;

   public B getB() {
     return b;
   }

   public static class B {
      String day;
      HashMap<String, ArrayList<Date>> locationTimes;

      public B() { 
          locationTimes = new HashMap<String, ArrayList<Date>>();
          day = "Monday"
      }

      public String getDay() {
        return day;
      }
  }
}

Then you can access the attrbutes from B like this: 

public class C {
   private A a;

   public void doSomething() {
      a.getB().getDay();
   }
}

Edit: You need your class B to either be private or public static.

Upvotes: 3

MrSalmon
MrSalmon

Reputation: 89

I am guessing you do not have an instance of your inner class? In that case you should make that yourself.

Within the outer class you can create a new instance of the inner class

public class Outer {
   Inner myInner;

   public Outer(){
       myInner = new Inner();
   }
}

And if you need to access the inner class directly from the outside, you could have a getter method for that instance.

This answer is different from Dimi's in that (s)he has changed changed your inner class to a nested static class which is different from the original question. (Also, it is incomplete, and not the intended way to use static nested classes)

Upvotes: 0

Christoph Hirte
Christoph Hirte

Reputation: 26

Yeah, you need to have an instance of B somewhere.

In your case the container is creating an instance of A like:

public class C {

@Inject
A a;

 void someMethod() {
   a.doit();
   A.B b = new A.B();
   b.doitToo(); // will work
 }
}

Upvotes: 0

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