Question

Is there a way to toggle a read-only mode so when you click any object in your window it simply returns what you clicked, ignoring the object’s usual event handling? IE, while in this “read-only” mode, if you click on a Button, it simply returns the button, not actually pressing the button. Then I could do something like:

if ("thing pressed" == button) "do this";
else if ("thing pressed" == panel) "do that";
else "do nothing";

Here’s my code, its a frame with 3 colored boxes. Clicking the 2nd box, the 3rd box, or the background will display a message. Clicking box 1 does nothing. I like using new mouse adapters so I want to do it this way.

Now what I want is when you click box 1, box 1 is treated as selected (if that helps you get the picture). Then if you click anywhere, including box 1 again, box 1 is deselected and nothing else (meaning that box 2, box 3. or the background’s message will display). At that time, only if box 2 or 3 were clicked, they will still not display their normal message but a different message would be displayed.

I’m very sorry if I come off a little short.

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Labels {
    public static void main(String[] args) {
        new Labels();
    }

    Square l1, l2, l3;
    public Labels() {
        JFrame frame = new JFrame();
        JPanel panel = new JPanel();
        l1 = new Square();
        l2 = new Square();
        l3 = new Square();

        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(120, 150);
        frame.setResizable(false);

        panel.setVisible(true);
        panel.setLayout(null);
        l1.setLocation(5, 5);
        l2.setLocation(5, 60);
        l3.setLocation(60, 5);

        l2.setColor("yellow");
        l3.setColor("black");

        l1.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                //do nothing
            }
        });

        l2.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("Pushed label 2");
            }
        });
        l3.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("Pushed label 3");
            }
        });
        panel.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("pushed background");
            }
        });

        frame.add(panel);
        panel.add(l1);
        panel.add(l2);
        panel.add(l3);
    }

    class Square extends JLabel{
        Color color = Color.blue;

        public Square() {
            // TODO Auto-generated constructor stub\
            setVisible(true);
            setSize(50,50);
        }

        public void paint(Graphics g) {
            super.paint(g);
            g.setColor(color);
            g.fillRect(0, 0, 50, 50);
        }
        public void setColor(String color){
            if (color == "white") this.color = Color.white;
            else if (color == "black") this.color = Color.black;
            else if (color == "yellow") this.color = Color.yellow;
            else {
                System.out.println("Invalid color");
                return;
            }
            repaint();
        }
    }
}

Answer 1

Don’t disable anything. Simply change the state of your class, perhaps by using a few boolean flag variables/fields and change these flags depending on what is pressed.

So have boolean fields called label1PressedLast, label2PressedLast, and label3PressedLast or something similar, and when a label is pressed, check the states of all other flags and have your program’s behavior change depending on the state of these flags and the label that was just pressed. Then set all flags to false except for the one corresponding to the label that was just pressed.

For example, this little program reacts only if the first and then the third JLabel have been pressed:

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;

import javax.swing.*;

public class FlagEg extends JPanel {
   private static final int LABEL_COUNT = 3;
   private JLabel[] labels = new JLabel[LABEL_COUNT];
   private boolean[] flags = new boolean[LABEL_COUNT];

   public FlagEg() {
      setLayout(new GridLayout(1, 0, 20, 0));
      setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));

      // panel mouse listener
      addMouseListener(new MouseAdapter() {
         @Override
         public void mousePressed(MouseEvent arg0) {
            inactivateAll();
         }
      });

      MouseListener labelsMouseListener = new MouseAdapter() {
         @Override
         public void mousePressed(MouseEvent mouseEvt) {
            myMousePressed(mouseEvt);
         }
      };

      // create JLabels and add MouseListener
      for (int i = 0; i < labels.length; i++) {
         labels[i] = new JLabel("Label " + (i + 1));
         labels[i].addMouseListener(labelsMouseListener);
         labels[i].setOpaque(true);
         labels[i].setBorder(BorderFactory.createLineBorder(Color.black));
         add(labels[i]);
      }
   }

   private void inactivateAll() {
      for (int i = 0; i < labels.length; i++) {
         labels[i].setBackground(null);
         flags[i] = false;
      }
   }

   private void myMousePressed(MouseEvent mouseEvt) {
      JLabel label = (JLabel) mouseEvt.getSource();

      // which label was pressed?
      int index = -1;
      for (int i = 0; i < labels.length; i++) {
         if (label == labels[i]) {
            index = i;
         }
      }

      // check if first label and then third pressed:
      if (flags[0] && index == 2) {
         System.out.println("first and then third label pressed!");
      }

      // reset all labels and flags to initial state
      inactivateAll();

      // set pressed label background color and set flag of label just pressed
      labels[index].setBackground(Color.pink);
      flags[index] = true;

   }

   private static void createAndShowGui() {
      FlagEg mainPanel = new FlagEg();

      JFrame frame = new JFrame("Flag Example");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

Logic iteration two: only label 1 is the “primer” JLabel. This is actually easier to implement, because now you only need one boolean flag, that representing label 1 being pressed:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

@SuppressWarnings("serial")
public class FlagEg2 extends JPanel {
   private static final int LABEL_COUNT = 3;
   private JLabel[] labels = new JLabel[LABEL_COUNT];

   private boolean label1Flag = false;

   public FlagEg2() {
      setLayout(new GridLayout(1, 0, 20, 0));
      setBorder(BorderFactory.createEmptyBorder(15, 15, 15, 15));

      // panel mouse listener
      addMouseListener(new MouseAdapter() {
         @Override
         public void mousePressed(MouseEvent arg0) {
            inactivateAll();
         }
      });

      MouseListener labelsMouseListener = new MouseAdapter() {
         @Override
         public void mousePressed(MouseEvent mouseEvt) {
            myMousePressed(mouseEvt);
         }
      };

      // create JLabels and add MouseListener
      for (int i = 0; i < labels.length; i++) {
         labels[i] = new JLabel("Label " + (i + 1));
         labels[i].addMouseListener(labelsMouseListener);
         labels[i].setOpaque(true);
         labels[i].setBorder(BorderFactory.createLineBorder(Color.black));
         add(labels[i]);
      }
   }

   private void inactivateAll() {
      for (int i = 0; i < labels.length; i++) {
         labels[i].setBackground(null);
         label1Flag = false;
      }
   }

   private void myMousePressed(MouseEvent mouseEvt) {
      JLabel label = (JLabel) mouseEvt.getSource();

      // which label was pressed?
      int index = -1;
      for (int i = 0; i < labels.length; i++) {
         if (label == labels[i]) {
            index = i;
         }
      }

      if (label1Flag) {
         if (index == 1) {
            System.out.println("Label 1 and label 2 pressed");
         } else if (index == 2) {
            System.out.println("Label 1 and label 3 pressed");
         }

      }

      // reset all labels and flags to initial state
      inactivateAll();

      // if label1, then activate it
      if (index == 0) {
         labels[0].setBackground(Color.pink);
         label1Flag = true;
      }

   }

   private static void createAndShowGui() {
      FlagEg2 mainPanel = new FlagEg2();

      JFrame frame = new JFrame("Flag Example");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}