Adding values to an ArrayList<Number> each time a button is pressed

Question

this is my first post here, hope i'll get it right!!

what i did i created a NxN board with JButtons indicating the coordinates from [0, 0] to [9, 9]. each time a button is clicked the console shows the coordinates and what i tried to do is to save those coordinates in an ArrayList that will be displayed by pressing a second button in another window...nothing fancy, sorry, just wrapping my head around basic concepts...

the problem is that i can't get the values to be saved into the ArrayList and i can't then recall it once i press the second button... attached the codes for my classes...each one is in a different file.

Board.java

public class Board{

public Board(){

    JFrame win = new JFrame ();
    GridLayout layout = new GridLayout(10, 10);
    win.setLayout(layout);
    for (int row1 = 0; row1 < 10 ; row1 = row1+1){
        for (int col1 = 0; col1 < 10; col1 = col1+1){
            JPanel jp = new JPanel();
            JButton jb = new JButton("[" + row1 + "," + col1 + "]");
            jb.addActionListener(new ButtonEventHandler(row1, col1));
            jp.add(jb);
            win.add(jp);
        }
        win.setVisible(true);
        win.pack();
}

    JFrame win2 = new JFrame("Stored values");
    win2.setVisible(true);
    JPanel jp2 = new JPanel();
    win2.add(jp2);
    JButton jb2 = new JButton("Check Log");
    jb2.addActionListener(new Position(win2, jb2));
    jp2.add(jb2);
    win2.pack();
}}

ButtonEventHandler.java

public class ButtonEventHandler implements ActionListener {


private int _row1;
private int _col1;
private ArrayList<Number> _list;


public ButtonEventHandler(int row1, int col1){

    _row1 = row1;
    _col1 = col1;
    _list = new ArrayList<Number>();
}

@Override
public void actionPerformed(ActionEvent e) {
    System.out.println("Position: " + _row1 + ", " + _col1);
    _list.add(_row1);
    _list.add(_col1);
}

public ArrayList<Number> getList(){

    return _list;
}}

Position.java

public class Position implements ActionListener  {

private JFrame _win2;

private JButton _jb2;
private int _row1;
private int _col1;
private ArrayList<Number> _list;

private ButtonEventHandler beh = new ButtonEventHandler(_row1, _col1);


public Position(JFrame win2, JButton jb2){
    _win2 = win2;
    _jb2 = jb2;     
}

@Override
public void actionPerformed(ActionEvent e) {

    System.out.println(beh.getList());      
}
}

thanks so much for the help!!

Seb

tnx for formatting the post properly!

TriRook
– TriRook

2012-05-04 03:25:08 +00:00
Commented May 4, 2012 at 3:25 — TriRook
– TriRook, Commented May 4, 2012 at 3:25

Sergey Kalinichenko · Accepted Answer · 2012-05-04 02:52:19Z

1

The problem in your code is that you don't have one array list: you have many array lists. Each button handler has its own!

You should make one array list, and share it among all your handlers by passing it to their constructors.

public Position(JFrame win2, JButton jb2, AttayList<Number> list){
    _win2 = win2;
    _jb2 = jb2;
    _list = list;
}

public ButtonEventHandler(int row1, int col1, AttayList<Number> list) {
    _row1 = row1;
    _col1 = col1;
    _list = list;
}

public Board(){
    JFrame win = new JFrame ();
    GridLayout layout = new GridLayout(10, 10);
    win.setLayout(layout);
    ArrayList myList = new ArrayList<Number>();
    // In the code below, use myList as the last parameter to the constructors of ButtonEventHandler and Position
    ...

}

answered May 4, 2012 at 2:52

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

TriRook Over a year ago

tnx for the reply...i see what u mean...but if i put the code like that when i click the button to check print the ArrayList out i get only "null" in the console....hmmmm....do i need to create i.e. a setList where i set the value of the list before the accessor method?

Sergey Kalinichenko Over a year ago

@Seb No, you already created an instance of the list in your Board constructor. You need to make sure that all 100 buttons get this list as the third parameter of their constructors, and that the Position gets the same instance as its last constructor parameter too.

TriRook Over a year ago

both ButtonEventHandlerand Position in the constructor, and in their instantiation in the Board class, have as third parameter list...in Position i have it like this private ArrayList<Number> _list; private ButtonEventHandler beh = new ButtonEventHandler(_row1, _col1, _list);...would that be ok?

Sergey Kalinichenko Over a year ago

@Seb Could you update the question? The comments are not as readable as the question because of the formatting issues.

TriRook · Accepted Answer · 2012-05-04 17:34:23Z

0

ok, i had it to work :)

i changed the constructors as suggested, in the Position class i got the rid of

private ButtonEventHandler beh = new ButtonEventHandler(_row1, _col1, _list);

and changed the ActionPerformed to:

@Override
public void actionPerformed(ActionEvent e) {
    System.out.println(beh.getList()); //previous code, changed with the one below
    System.out.println(_list);
}

in this way i didn't need anymore the getList method in the Board class!

thanks for the help!!

edited May 4, 2012 at 17:34

answered May 4, 2012 at 17:02

TriRook

1671 gold badge3 silver badges19 bronze badges

Collectives™ on Stack Overflow

Adding values to an ArrayList<Number> each time a button is pressed

2 Answers 2

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related