sending and arraylist in one class as an element to an arraylist of another class.

Posted on 2004-09-01
Last Modified: 2010-03-31
I have an arraylist declared in my class X

===>     ArrayList arr = new Arraylist();
Im my actionPerformed method I've add'd an element to my arrayList everytime a button was clicked.
===>     arr.add("Element 1"); ..etc..

now I have another class Y which contains another ArrayList -

im trying to send the arraylist in my class X as an element to the arraylist that i have created in my class Y.
- How can i go about doing that, i know its easy but i can't seem to get it.
Question by:technomania
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 3
LVL 35

Accepted Solution

girionis earned 30 total points
ID: 11956553
You need to obtain the reference of your class Y. Then do something like:

class Y
    private ArrayList listFromClassX = null;
    public void setArrayList(ArrayList list)
       listFromClassX = list;

   // use the listFromClassX here

class X
   Y y = new Y();
   ArrayList arr = new Arraylist();
   arr.add("Element 1"); ..etc..



Author Comment

ID: 11957494
Let me rephrase this.

How do I send/set my ArrayList arr,  in class X to my ArrayList arrList,  in class Y.

withotu getting null an an error etc etc..
LVL 35

Expert Comment

ID: 11957640
My example above does exactly this.
MS Dynamics Made Instantly Simpler

Make Your Microsoft Dynamics Investment Count  & Drastically Decrease Training Time by Providing Intuitive Step-By-Step WalkThru Tutorials.


Author Comment

ID: 11957707
when do i do:       y.setArrayList(arr);

I'm adding elements in my actionPerformed

and in my class Y how would i set the arraylist recieved from X

Notice: ill add an extra 10 point for all your help...  sorry for the repetitive questions im a new to programming
LVL 35

Expert Comment

ID: 11957877
> when do i do:       y.setArrayList(arr);

Where you want to set the array. But you have to replace y and arr with the variables you are using.

> and in my class Y how would i set the arraylist recieved from X

You need to have a setter method in your Y class that will be called from X. Something like

Y class

private ArrayList arr;
public void setList(ArrayList list)
    arr = list;

X class
y.setList(<your list here>);

Author Comment

ID: 11958534
y is my class name - doesn't    y.setList(<your list here>);  have to be assigned to a variable

if i used the method y.setList() from my class Y in my class X,   how does the arraylist in Y know what its new value is if the operation is done in X.
LVL 35

Expert Comment

ID: 11960833
>  how does the arraylist in Y know what its new value is if the operation is done in X.

It will know since you will pass the array list reference in your setList() method. The setList takes a parameter which is of type ArrayList.


Featured Post

Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

By the end of 1980s, object oriented programming using languages like C++, Simula69 and ObjectPascal gained momentum. It looked like programmers finally found the perfect language. C++ successfully combined the object oriented principles of Simula w…
In this post we will learn how to connect and configure Android Device (Smartphone etc.) with Android Studio. After that we will run a simple Hello World Program.
This video teaches viewers about errors in exception handling.
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …

617 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question