Question

I have a method which takes an array as a parameter from another class:

public void memPass(Memory[] memLocList) {

    memList = memLocList;

            for (int i = 0; i < 10; i++) {
        System.out.println(memList[i].getSomething());
    }
}

-EDIT-
The above prints out 10 values (integers) but if I try the same in the other method with an integer between 0 & 10 I get an NPE.

Can anyone tell me how to access the elements of this array from another method, which also takes in a parameter from another class?

I’m trying to do something along these lines:

public void accessArray(int mem) {

           int someInt = memList[mem].getSomething();
}

-EDIT- Sorry, I should add that this gives a NullPointerException.

-NEW EDIT-

OK, I’ve now edited the code so that all I have in the class is:

public class PLoop {

// instance variable
public Memory[] memlist;

  // method 1 
  public void memPass(Memory[] memLocList) {

   memList = memLocList;
   System.out.println(memList.length);
  }

  // method 2
  public void accessArray(int mem) {

   System.out.println(memList.length);
  }
}

The first method prints an integer representing the length of “memList” and the second gives an NPE.

Answer 1

If I’m understanding you right, you want to be able to store memLocList then access it later? If so, I can’t see what creating an instance variable wouldn’t work.

public class Test {
    public Memory[] memlist;

    public void memPass(Memory[] memLocList) {
        memList = memLocList;
    }

    public void accessArray(int mem) {
        int someInt = memList[mem].getSomething();
    }
}

Of course, I don’t work in Java enough any more, so it might not be possible to create and assign an instance variable like that. But you could always store the elements in another container.

public class Test {
    public List<Memory> memlist;

    public void memPass(Memory[] memLocList) {
        memlist = new ArrayList<Memory>(Arrays.asList(memLocList));
    }

    public void accessArray(int mem) {
        int someInt = memList.get(mem).getSomething();
    }
}

Sorry if I have any syntax errors. But you get the main idea.