遇到了需要从另一个类中获取boolean变量的问题。
我有以下for-loop，boolea n和if-else条语句
import java.awt.*;
import javax.swing.*;
import java.awt.Color.*;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import java.util.Random;
public class Checkers extends JFrame
{
Random random = new Random();
private final int ROWS = 2;
private final int COLS = 5;
private final int GAP = 2;
private final int NUM = ROWS * COLS;
private int i;
private int score;
private JPanel pane = new JPanel(new GridLayout(ROWS,COLS, GAP,GAP));
private JPanel pane2 = new JPanel();
private JPanel pane3 = new JPanel();
private JButton btn1 = new JButton("Play A Game");
private JButton btn2 = new JButton("Exit");
private JButton btn3 = new JButton("Easy");
private JButton btn4 = new JButton("Intermediate");
private JButton btn5 = new JButton("Difficult");
private JLabel lbl1 = new JLabel ("score: " + score);
private JLabel gameLost = new JLabel("You lose! You got: " + score + " points");
private JButton btnRestart = new JButton("Restart");
private MyPanel [] panel = new MyPanel[NUM];
private Color col1 = Color.RED;
private Color col2 = Color.WHITE;
private Color col3 = Color.GREEN;
private Color tempColor;
private boolean isPanelDisabled;
//Starts the checkers GUI, calling the constructor below this.
public static void main(String[] args){
new Checkers();
}
//Sets the dimensions of the GUI, visibility, background color and
//contents via the setBoard();
public Checkers()
{
super("Checkers");
setSize(600,600);
setVisible(true);
setBackground(Color.BLACK);
setBoard();
}
//Makes the grid, contains a conditional boolean, adds the panels to grid based on i value.
//sets Colours accordingly
public void setBoard()
{
boolean isPanelDisabled = false;
for (int i = 0; i < panel.length; i++) {
panel[i] = new MyPanel(this);
pane.add(panel[i]);
if (i % COLS == 0) {
tempColor = col1;
}
if (i == 9 || i <8) {
panel[i].setBackground(col1);
}
if(i == 8){
isPanelDisabled = true;
panel[i].setBackground(col3);
}
}
//pane background colour and the size of this pane.
pane.setBackground(Color.BLACK);
pane.setPreferredSize(new Dimension(300,300));
//pane background colour and size of this pane.
pane2.setBackground(Color.white);
pane2.setPreferredSize(new Dimension(300,300));
//directions on the board where these panes appear.
add(pane, BorderLayout.WEST);
add(pane2, BorderLayout.EAST);
pane2.add(lbl1);
pane2.add(btnRestart);
btnRestart.addActionListener( e -> restartBoard());
pane2.setLayout(new BoxLayout(pane2, BoxLayout.PAGE_AXIS));
}
//increments the score for the user based on current points.
public void incrementScore(){
if (score != 5){
score++;
lbl1.setText("Score: " + Integer.toString(score));
}
else if(score == 5){
lbl1.setText("Congratulations!, you've won!, your score is:" + score);
}
}
}
和这个mouseClicked事件
import java.awt.Color;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.*;
import java.awt.event.*;
import javax.swing.JPanel;
public class MyPanel extends JPanel implements MouseListener, ActionListener {
private final Checkers checkers;
private boolean isPanelDisabled;
//MyPanel Constructor that initiates a instance of checkers.
public MyPanel(Checkers checkers) {
this.checkers = checkers;
addMouseListener(this);
}
@Override
public void actionPerformed(ActionEvent e){
}
// Sets the panel colours according to their int number and the boolean condiiton.
@Override
public void mouseClicked(MouseEvent e) {
if (isPanelDisabled == true){
setBackground(Color.CYAN);
}
else{
setBackground(Color.BLACK);
checkers.incrementScore();
}
}
我的预期结果应该是，如果用户单击该网格中的第8个面板，则该面板的颜色在被按下时将是青色而不是黑色，但是它无法访问布尔变量？我在哪里错了？
答案 0 :(得分：1)
您的问题涉及不同类的对象之间的通信，并且有几种方法可以实现此目的，但是最基本的方法是将一个类中的对象的方法调用到另一个类中。
首先让我们设置问题，...我创建了名为MyPanel2和Checkers2的类，以区别于您的类。
在MyPanel2中说，我们有一个Checkers2字段和一个名为selected的布尔值字段，设置为false：
private Checkers2 checkers;
private boolean selected = false;
以及适当的布尔型getter和setter：
public void setSelected(boolean selected) {
this.selected = selected;
}
public boolean isSelected() {
return selected;
}
并说在Checkers2类中，数组中包含10个MyPanel2实例，并且希望用户能够“选择”该类的实例，但只允许选择其中的7个，并假设要使用当前正在使用的设置，可以给主类一个方法public boolean isPanelDisabled()，并让MyPanel2类调用此方法来确定是否允许选择。因此，在MyPanel2中，您可以拥有一个类似以下内容的MouseListener：
@Override
public void mousePressed(MouseEvent e) {
if (selected) {
return;
}
// call the Checkers2 boolean method to check
if (checkers.isPanelDisabled()) {
setBackground(DISABLED_COLOR);
} else {
setBackground(SELECTED_COLOR);
setSelected(true);
}
}
在Checkers2 .isPanelDisabled()方法中，您将遍历MyPanel2实例数组以查看已选择了多少实例，这样可以起作用：
public boolean isPanelDisabled() {
int count = 0;
for (MyPanel2 panel2 : myPanels) {
if (panel2.isSelected()) {
count++;
}
}
return count >= MAX_COUNT;
}
整个MCVE可测试代码如下：
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Checkers2 extends JFrame {
private static final int MAX_COUNT = 7;
private final int ROWS = 2;
private final int COLS = 5;
private final int GAP = 2;
private final int NUM = ROWS * COLS;
private MyPanel2[] myPanels = new MyPanel2[NUM];
public Checkers2() {
super("Checkers");
setDefaultCloseOperation(EXIT_ON_CLOSE);
JPanel gridPanel = new JPanel(new GridLayout(ROWS, COLS, 1, 1));
gridPanel.setBackground(Color.BLACK);
gridPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
for (int i = 0; i < myPanels.length; i++) {
MyPanel2 myPanel = new MyPanel2(this);
gridPanel.add(myPanel);
myPanels[i] = myPanel;
}
JButton resetButton = new JButton("Reset");
resetButton.setMnemonic(KeyEvent.VK_R);
resetButton.addActionListener(evt -> {
for (MyPanel2 myPanel2 : myPanels) {
myPanel2.reset();
}
});
JButton exitButton = new JButton("Exit");
exitButton.setMnemonic(KeyEvent.VK_X);
exitButton.addActionListener(evt -> System.exit(0));
JPanel buttonPanel = new JPanel();
buttonPanel.add(resetButton);
add(gridPanel);
add(buttonPanel, BorderLayout.PAGE_END);
pack();
setLocationRelativeTo(null);
}
public boolean isPanelDisabled() {
int count = 0;
for (MyPanel2 panel2 : myPanels) {
if (panel2.isSelected()) {
count++;
}
}
return count >= MAX_COUNT;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
new Checkers2().setVisible(true);
});
}
}
class MyPanel2 extends JPanel {
private static final int PREF_W = 200;
private static final int PREF_H = PREF_W;
private static final int GR = 240;
public static final Color BASE_COLOR = new Color(GR, GR, GR);
public static final Color DISABLED_COLOR = Color.CYAN;
public static final Color SELECTED_COLOR = Color.BLACK;
private Checkers2 checkers;
private boolean selected = false;
public MyPanel2(Checkers2 checkers) {
setBackground(BASE_COLOR);
this.checkers = checkers;
setPreferredSize(new Dimension(PREF_W, PREF_H));
addMouseListener(new MyMouse());
}
public void setSelected(boolean selected) {
this.selected = selected;
}
public boolean isSelected() {
return selected;
}
public void reset() {
setBackground(BASE_COLOR);
setSelected(false);
}
private class MyMouse extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
if (selected) {
return;
}
if (checkers.isPanelDisabled()) {
setBackground(DISABLED_COLOR);
} else {
setBackground(SELECTED_COLOR);
setSelected(true);
}
}
}
}
另一个选项是提取MyPanel的所有逻辑 ，并将其放入主程序中，例如：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
@SuppressWarnings("serial")
public class Checkers3 extends JPanel {
private static final int MAX_COUNT = 7;
private final int ROWS = 2;
private final int COLS = 5;
private final int GAP = 2;
private final int NUM = ROWS * COLS;
private MyPanel3[] myPanels = new MyPanel3[NUM];
public Checkers3() {
JPanel gridPanel = new JPanel(new GridLayout(ROWS, COLS, 1, 1));
gridPanel.setBackground(Color.BLACK);
gridPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
MyMouse myMouse = new MyMouse();
for (int i = 0; i < myPanels.length; i++) {
MyPanel3 myPanel = new MyPanel3();
myPanel.addMouseListener(myMouse);
gridPanel.add(myPanel);
myPanels[i] = myPanel;
}
JButton resetButton = new JButton("Reset");
resetButton.setMnemonic(KeyEvent.VK_R);
resetButton.addActionListener(evt -> {
for (MyPanel3 myPanel : myPanels) {
myPanel.reset();
}
});
JButton exitButton = new JButton("Exit");
exitButton.setMnemonic(KeyEvent.VK_X);
exitButton.addActionListener(evt -> System.exit(0));
JPanel buttonPanel = new JPanel();
buttonPanel.add(resetButton);
setLayout(new BorderLayout());
add(gridPanel);
add(buttonPanel, BorderLayout.PAGE_END);
}
public boolean isPanelDisabled() {
int count = 0;
for (MyPanel3 panel : myPanels) {
if (panel.isSelected()) {
count++;
}
}
return count >= MAX_COUNT;
}
private class MyMouse extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
MyPanel3 myPanel = (MyPanel3) e.getSource();
if (myPanel.isSelected()) {
return; // it's already selected
} else if (isPanelDisabled()) {
myPanel.setSelected(false);
} else {
myPanel.setSelected(true);
}
}
}
private static void createAndShowGui() {
Checkers3 mainPanel = new Checkers3();
JFrame frame = new JFrame("Checkers");
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(() -> createAndShowGui());
}
}
@SuppressWarnings("serial")
class MyPanel3 extends JPanel {
private static final int PREF_W = 200;
private static final int PREF_H = PREF_W;
private static final int GR = 240;
public static final Color BASE_COLOR = new Color(GR, GR, GR);
public static final Color DISABLED_COLOR = Color.CYAN;
public static final Color SELECTED_COLOR = Color.BLACK;
private boolean selected = false;
public MyPanel3() {
setBackground(BASE_COLOR);
setPreferredSize(new Dimension(PREF_W, PREF_H));
}
public void setSelected(boolean selected) {
this.selected = selected;
Color background = selected ? SELECTED_COLOR : DISABLED_COLOR;
setBackground(background);
}
public boolean isSelected() {
return selected;
}
public void reset() {
setSelected(false);
setBackground(BASE_COLOR);
}
}
但是 BEST 选项是将所有逻辑放在一个或多个单独的模型类中，并使GUI尽可能哑。