一个类在实例化另一个类之后如何调用方法？
问题描述：
我对这个社区很陌生。在发布这个问题（以及研究解决方案）之前，我试图赶上所有规则的速度。如果因无知而冒犯或破坏任何规则，我表示歉意。请原谅我可怕的代码，我仍然在学习。谢谢你的理解！一个类在实例化另一个类之后如何调用方法？
编辑：我已经添加了额外的信息，并尝试了不同的方法来解决我遇到的这个问题。我修改了下面的部分代码。
我正在构建一个简单的游戏场面板和控制面板的足球比赛。游戏场显示GUI上的所有玩家和铲球。控制面板设置游戏的难度，启动计时器和四分卫的类型。我遇到了一个道路块，我的所有代码都能够正确编译，但是当调用GameField类的set方法来更新分数时，它会通过我的JTextArea Score Keeper更新变量而不是实际分数。
我已经在GameField类中实例化了ControlPanel。我还测试了一个System.out.println（），它显示它确实正在更新变量。更新类间允许更新JTextArea？
GameField.java
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class GameField extends JPanel implements KeyListener {
ControlPanel cp = new ControlPanel();
// Game pieces
private JButton playerIcon = new JButton("RB");
private JButton tackleIcon1 = new JButton("LB");
private JButton tackleIcon2 = new JButton("LB");
private JButton fieldGoal = new JButton("FG");
// Player and Tackle locations
private int playerPositionX = 100;
private int playerPositionY = 500;
private int tackle1PositionX = 1200;
private int tackle1PositionY = 400;
private int tackle2PositionX = 1200;
private int tackle2PositionY = 600;
// Player variable speeds
private int playerSpeed = 20;
public GameField() {
setLayout(null);
setBackground(Color.green);
add(playerIcon);
playerIcon.setBounds(new Rectangle(getPlayerPositionX(), getPlayerPositionY(), 80, 30));
add(tackleIcon1);
tackleIcon1.setBounds(new Rectangle(getTackle1PositionX(), getTackle1PositionY(), 100, 50));
add(tackleIcon2);
tackleIcon2.setBounds(new Rectangle(getTackle2PositionX(), getTackle2PositionY(), 100, 50));
add(fieldGoal);
fieldGoal.setBounds(new Rectangle(1600, 100, 100, 800));
playerIsTackled();
setFocusable(true);
addKeyListener(this);
}
public void playerIsTackled() {
Rectangle playerRect = playerIcon.getBounds();
Rectangle tackle1Rect = tackleIcon1.getBounds();
Rectangle tackle2Rect = tackleIcon2.getBounds();
if (playerRect.intersects(tackle1Rect) || playerRect.intersects(tackle2Rect)) {
setPlayerPositionX(100);
setPlayerPositionY(500);
setTackle1PositionX(1200);
setTackle1PositionY(400);
setTackle2PositionX(1200);
setTackle2PositionY(600);
playerIcon.setBounds(getPlayerPositionX(), getPlayerPositionY(), 80, 30);
tackleIcon1.setBounds(getTackle1PositionX(), getTackle1PositionY(), 100, 50);
tackleIcon2.setBounds(getTackle2PositionX(), getTackle2PositionY(), 100, 50);
cp.setCurrentTackles(cp.getCurrentTackles() + 1);
System.out.println(cp.getCurrentTackles());
}
}
public void playerScored() {
Rectangle playerRect = playerIcon.getBounds();
Rectangle fieldGoalRect = fieldGoal.getBounds();
if (playerRect.intersects(fieldGoalRect)) {
setPlayerPositionX(100);
setPlayerPositionY(500);
setTackle1PositionX(1200);
setTackle1PositionY(400);
setTackle2PositionX(1200);
setTackle2PositionY(600);
playerIcon.setBounds(getPlayerPositionX(), getPlayerPositionY(), 80, 30);
tackleIcon1.setBounds(getTackle1PositionX(), getTackle1PositionY(), 100, 50);
tackleIcon2.setBounds(getTackle2PositionX(), getTackle2PositionY(), 100, 50);
cp.setCurrentScore(cp.getCurrentScore() + 1);
System.out.println(cp.getCurrentScore());
}
}
public void moveToPlayer() {
if (getTackle1PositionX() > getPlayerPositionX()) {
setTackle1PositionX(getTackle1PositionX() - 1);
} else {
setTackle1PositionX(getTackle1PositionX() + 1);
}
if (getTackle1PositionY() > getPlayerPositionY()) {
setTackle1PositionY(getTackle1PositionY() - 1);
} else {
setTackle1PositionY(getTackle1PositionY() + 1);
}
getTackleIcon1().setBounds(getTackle1PositionX(), getTackle1PositionY(), 100, 50);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
requestFocusInWindow();
playerIsTackled();
playerScored();
}
@Override
public void keyTyped(KeyEvent e) {
}
@Override
public void keyPressed(KeyEvent e) {
int k = e.getKeyCode();
if (k == e.VK_LEFT && getPlayerPositionX() > 0) {
setPlayerPositionX(getPlayerPositionX() - getPlayerSpeed());
}
if (k == e.VK_RIGHT && getPlayerPositionX() < 1703) {
setPlayerPositionX(getPlayerPositionX() + getPlayerSpeed());
}
if (k == e.VK_UP && getPlayerPositionY() > 0) {
setPlayerPositionY(getPlayerPositionY() - getPlayerSpeed());
}
if (k == e.VK_DOWN && getPlayerPositionY() < 1089) {
setPlayerPositionY(getPlayerPositionY() + getPlayerSpeed());
}
getPlayerIcon().setBounds(getPlayerPositionX(), getPlayerPositionY(), 80, 30);
}
下面是ControlPanel.java。在actionPerformed方法中，您可以看到我添加了getScore（）。setText（）方法来更新分数。如果我用任何整数替换getCurrentScore（）方法，它会正确更新那里的分数。
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.Hashtable;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class ControlPanel extends JPanel implements ActionListener, ChangeListener {
private JButton start;
private JButton stop;
private JSlider speed;
private JComboBox playerList;
private Timer tim;
private int delay = 1000;
private int i = 0;
private int currentScore = 0;
private int currentTackles = 0;
private JTextArea timer = new JTextArea("Timer: " + 0, 1, 6);
private JTextArea score = new JTextArea("Field Goals: " + currentScore + " Tackles: " + currentTackles, 1, 16);
private String[] playerStyle = {"Slow Runner", "Running Back", "All Star"};
public ControlPanel() {
super();
setBackground(Color.darkGray);
// Game controls
start = new JButton("Start");
stop = new JButton("Stop");
speed = new JSlider(JSlider.HORIZONTAL, 0, 2, 1);
playerList = new JComboBox(getPlayerStyle());
// Slider label
Hashtable labelTable = new Hashtable();
labelTable.put(new Integer(0), new JLabel("Slow"));
labelTable.put(new Integer(1), new JLabel("Normal"));
labelTable.put(new Integer(2), new JLabel("Fast"));
speed.setLabelTable(labelTable);
speed.setPaintLabels(true);
// Combo box dropdown
playerList.setSelectedIndex(1);
// Timer
tim = new Timer(getDelay(), this);
// Add methods
add(start);
add(stop);
add(timer);
add(speed);
add(score);
add(playerList);
// Event listeners
start.addActionListener(this);
stop.addActionListener(this);
speed.addChangeListener(this);
playerList.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JComboBox cb = (JComboBox) e.getSource();
String playerChoice = (String) cb.getSelectedItem();
playerList.setSelectedItem(playerChoice);
}
});
// Set focus to false on all game controls
start.setFocusable(false);
stop.setFocusable(false);
speed.setFocusable(false);
playerList.setFocusable(false);
}
@Override
public void actionPerformed(ActionEvent event) {
Object obj = event.getSource();
if (obj == getTim()) {
setI(getI() + 1);
getTimer().setText("Timer: " + getI());
getScore().setText("Field Goals: " + getCurrentScore() + " Tackles: " + getCurrentTackles());
}
if (obj == getStop()) {
getTim().stop();
}
if (obj == getStart()) {
getTim().start();
}
}
@Override
public void stateChanged(ChangeEvent e) {
JSlider source = (JSlider) e.getSource();
int currentSpeed = (int) source.getValue();
if (currentSpeed == 0) {
int delaySpeed = getTim().getDelay();
delaySpeed = (int) 2000;
getTim().setDelay(delaySpeed);
}
if (currentSpeed == 1) {
int delaySpeed = getTim().getDelay();
delaySpeed = (int) 1000;
getTim().setDelay(delaySpeed);
}
if (currentSpeed == 2) {
int delaySpeed = getTim().getDelay();
delaySpeed = (int) 500;
getTim().setDelay(delaySpeed);
}
}
MyJPanel.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class MyJPanel extends JPanel {
public MyJPanel() {
super();
setBackground(Color.gray);
setLayout(new BorderLayout());
ControlPanel gm = new ControlPanel();
GameField gf = new GameField();
add(gm, "North");
add(gf, "Center");
}
}
答
感谢@ D.B。我已经让我的代码按预期运行。因为我只打算有两个JPanel（控制面板和游戏面板），所以我添加了面板作为参数传递给对方。之后，代码开始按预期工作。谢谢你把我推向正确的一步！这是一个简单的错误。特别感谢@DaveyDaveDave激励我加倍努力！
改变我对我的主要的JPanel对象进行：
你可以做public class MyJPanel extends JPanel {
ControlPanel gm = new ControlPanel();
GameField gf = new GameField();
public MyJPanel() {
super();
setBackground(Color.gray);
setLayout(new BorderLayout());
add(gm, "North");
add(gf, "Center");
gf.setCp(gm);
gm.setGf(gf);
}
}
一件事是添加一些打印语句（'的System.out.println（）'）到您的代码，会告诉你什么** ** 正在发生。 “没有任何反应”对我们没有多大帮助。做一些调试，并告诉我们在什么时候你期望发生的事情与你所看到的事情不同。 – markspace
谢谢马克，我会回复我发现的内容。非常感谢！ – deuscode
你也可以在调试模式下运行你的程序，并把断点放在 –