CODEWITHSUNDEEP
javaswingbuttonif-statementjbutton
user1812027
user1812027

Reputation:

ActionListener finds the proper name (not string that appears) of pressed JButton?

I have encountered a problem I can't find the solution for, in Java revolving around JButtons.

As I want to keep my code 'cleaner', I have declared all my buttons using the following for loop:

JButton[] buttons= new JButton[10];
for(int i = 0;i < buttons.length;i++){
    buttons[i] = new JButton("Example "+i);
    contents2.add(buttons[i]);
    buttons[i].addActionListener(listener);}

And the actionListener listener is as follows:

ActionListener listener = new ActionListener() {
        public void actionPerformed (ActionEvent actionEvent) {
            if(actionEvent.getSource() == (JButton)buttons[1].getSource()){
                System.out.println("Test");
            }
        }
    };

However then buttons in if(actionEvent.getSource() == (JButton)buttons[1].getSource()) has Eclipse tell me Buttons cannot be resolved to a variable.

In that same line, I've also tried without the (JButton), without the .getSource() after buttons[1], and more combinations.

I have confused myself, however I simply want the action performed in the listener to happen if the button pressed was _.

Sorry for the confusion, but if you understand this, any help would be appreciated. I just keep getting strings other than what I desire.

Upvotes: 0

Views: 59

Answers (2)

Rod_Algonquin
Rod_Algonquin

Reputation: 26198

Instead of using source which does not exist, you can use the setActionCommand method to be used in your action listener.

sample:

ActionListener listener = new ActionListener() {
        public void actionPerformed (ActionEvent actionEvent) {
            String index = actionEvent.getActionCommand();

            switch(Integer.valueOf(index)){
                case 1: //your actions here for index 1 of button
                break;
            }
        }
    };

final JButton[] buttons= new JButton[10];
    for(int i = 0;i < buttons.length;i++){
        buttons[i] = new JButton("Example "+i);
        contents2.add(buttons[i]);
        buttons[i].setActionCommand(i+"");
        buttons[i].addActionListener(listener);
    }

As you could see the action command is the index of your button so you could use the switch statement for performing actions on each of your buttons.

case 1 means the index 1 of your Button array.

Upvotes: 1

MadProgrammer
MadProgrammer

Reputation: 347294

It's possible that the ActionListener is been declared before the JButton array.

Instead, declare buttons as a instance variable...

 public class SomeClass extends ... {
     private JButton[] buttons;

Then you should be able to reference buttons in your ActionListener using

if(actionEvent.getSource() == buttons[1]){

When constructing your buttons array, you will also need to make sure you are not shadowing your variables, for example...

buttons= new JButton[10]; 
for(int i = 0;i < buttons.length;i++){

Having said all that, if you want to clean up your code, then I would suggest you take a look at How to use Actions, which provides a re-usable API for actions, which can be attached to buttons, menu items and key bindings

Upvotes: 1

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