java - 在 Java 中切换只读

Question

有没有一种方法可以切换只读模式，这样当您单击窗口中的任何对象时，它只会返回您单击的内容，而忽略该对象的常规事件处理？ IE，在这种“只读”模式下，如果你点击一个按钮，它只是返回按钮，而不是实际按下按钮。然后我可以做类似的事情:

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

这是我的代码，它是一个包含 3 个彩色框的框架。单击第二个框、第三个框或背景将显示一条消息。单击框 1 没有任何作用。我喜欢使用新的鼠标适配器，所以我想这样做。

现在我想要的是当您单击框 1 时，框 1 被视为已选中(如果这有助于您了解图片)。然后，如果您再次单击任何地方，包括方框 1，方框 1 将被取消选择并且不会显示任何其他内容(这意味着方框 2、方框 3 或背景消息将显示)。那时，只有点击框 2 或 3 时，它们仍不会显示正常消息，而是会显示不同的消息。

如果我说得有点短，我很抱歉。

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

不要禁用任何东西。只需更改类的状态，也许可以使用一些 boolean 标志变量/字段，并根据按下的内容更改这些标志。

所以有 boolean 字段称为 label1PressedLast、label2PressedLast 和 label3PressedLast 或类似的东西，当按下标签时，检查状态所有其他标志，并让您的程序的行为根据这些标志的状态和刚刚按下的标签而改变。然后将所有标志设置为 false，除了对应于刚刚按下的标签的标志。

例如，这个小程序只有在按下第一个和第三个 JLabel 时才会使用react:

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();
         }
      });
   }
}

逻辑迭代二:只有标签 1 是“初级”JLabel。这实际上更容易实现，因为现在你只需要一个 boolean 标志，代表标签 1 被按下:

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();
         }
      });
   }
}