CODEWITHSUNDEEP
javaswingawt
Soham
Soham

Reputation: 13

Getting source of an event in Java

Is there any way to get the source of an event? I know event.getSource() however, is there any way to convert it into a string?

For example, if the source is a button, button1, is there anyway to assign the value button1 to a string variable? (I'm dealing with a lot of buttons and so, I can't write if statements)

Upvotes: 0

Views: 1784

Answers (3)

Giulio Biagini
Giulio Biagini

Reputation: 920

You can use a specific ActionListener for each JButton. Try this code:

private static String text;


public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(200, 200, 200, 200);
    frame.setLayout(new BorderLayout());

    JButton button1 = new JButton("Button 1");
    button1.addActionListener(new ActionListener() {
        @Override public void actionPerformed(ActionEvent e) {
            text = button1.getText();
            JOptionPane.showMessageDialog(null, "Text is: " + text);
        }
    });

    JButton button2 = new JButton("Button 2");
    button2.addActionListener(new ActionListener() {
        @Override public void actionPerformed(ActionEvent e) {
            text = button2.getText();
            JOptionPane.showMessageDialog(null, "Text is: " + text);
        }
    });

    frame.add(button1, BorderLayout.NORTH);
    frame.add(button2, BorderLayout.SOUTH);
    frame.setVisible(true);
}

Upvotes: 0

James Taylor
James Taylor

Reputation: 6258

For the sake of clarity:

The getSource() method returns the object from which the Event initially occurred. You could use this to get some sort of property from the element, like the text inside a label or the name of a button.

These are Strings, but if you chose to go this route, I would make sure you pick something that is uniform across all components that will be calling that ActionListerner.

This is where getActionCommand() might come in handy. You can set unique 'identifiers' when components are created, and the access them later.

JButton button = new JButton("Button");
button.setActionCommand("1");

JButton button = new JButton("Button");
button.setActionCommand("2");

Then you can compare these later using any method you like, or you could do something fancy, like this (because you said you didn't want to use if-else statements):

String command = e.getActionCommand();
int i = Integer.parseInt(command);

switch (i) {
    case 1: // do something
        break;
}

According to the Java docs:

Returns the command string associated with this action. This string allows a "modal" component to specify one of several commands, depending on its state. For example, a single button might toggle between "show details" and "hide details". The source object and the event would be the same in each case, but the command string would identify the intended action.

Keep in mind that I think this is best approach only if you are using one ActionListerner for lots of components. As another answer pointed out, you could just make unique ActionListeners per each button.

Hope this helps you!

Upvotes: 1

Gilbert Le Blanc
Gilbert Le Blanc

Reputation: 51485

You can pass anything you want to an action listener through the constructor, as DaaaahWhoosh stated in his comment.

package com.ggl.fse;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ButtonActionListener implements ActionListener {

    private String buttonText;

    public ButtonActionListener(String buttonText) {
        this.buttonText = buttonText;
    }

    @Override
    public void actionPerformed(ActionEvent event) {
        // TODO Auto-generated method stub

    }

}

The buttonText String will be available in the actionPerformed method.

Upvotes: 0

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