当我运行程序时，直到我改变屏幕大小（setResizable = true;）才会出现JButtons。
这是我的代码：
公共类MainMenu扩展了JPanel {
Kingdomcraft kd;
Screen screen;
JButton playSP;
JButton playMP;
JButton settings;
JButton fullscreen;
JButton quit;
JButton createWorld;
JButton addServer;
JSlider sound;
JSlider light;
JList worldList;
JList serverList;
JTextField worldName;
JTextField serverName;
JTextField serverIP;
JButton addNewWorld;
JButton addNewServer;
private Preferences prefs;
private int soundLevel;
private int lightLevel;
public static boolean isFullscreen = false;
public static boolean serverNameFilled = false;
public static boolean serverIPFilled = false;
public void run() {
kd = new Kingdomcraft();
screen = new Screen();
playSP = new JButton("Singleplayer");
playMP = new JButton("Multiplayer");
settings = new JButton("Settings");
fullscreen = new JButton("Fullscreen");
quit = new JButton("Quit");
createWorld = new JButton("Create World");
addServer = new JButton("Add Server");
sound = new JSlider();
light = new JSlider();
prefs = Preferences.userNodeForPackage(MainMenu.class);
soundLevel = prefs.getInt("SOUND_LEVEL", 50);
lightLevel = prefs.getInt("LIGHT_LEVEL", 100);
worldList = new JList();
serverList = new JList();
worldName = new JTextField();
serverName = new JTextField();
serverIP = new JTextField();
addNewWorld = new JButton("Add");
addNewServer = new JButton("Add");
this.setBackground(Color.BLACK);
if (kd.inMainMenu) {
add(playSP);
playSP.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
remove(sound);
remove(light);
remove(fullscreen);
remove(addServer);
remove(serverName);
remove(serverIP);
remove(addNewServer);
repaint();
add(createWorld);
createWorld.setSize(110, 25);
createWorld.setLocation(playSP.getX() - (playSP.getWidth() / 2) - 5, playSP.getY() + 35);
createWorld.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
add(worldName);
worldName.setSize(110, 25);
worldName.setLocation(createWorld.getX(), createWorld.getY() + 35);
worldName.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
add(addNewWorld);
addNewWorld.setSize(110, 25);
addNewWorld.setLocation(worldName.getX(), worldName.getY() + 35);
}
});
}
});
}
});
add(playMP);
playMP.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
remove(sound);
remove(light);
remove(fullscreen);
remove(createWorld);
remove(worldName);
remove(addNewWorld);
repaint();
add(addServer);
addServer.setSize(100, 25);
addServer.setLocation(playMP.getX() - (playMP.getWidth() / 2) - 5, playMP.getY() + 35);
addServer.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
add(serverName);
serverName.setSize(100, 25);
serverName.setLocation(addServer.getX(), addServer.getY() + 35);
serverName.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
MainMenu.serverNameFilled = true;
}
});
add(serverIP);
serverIP.setSize(100, 25);
serverIP.setLocation(serverName.getX(), serverName.getY() + 35);
serverIP.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
MainMenu.serverIPFilled = true;
}
});
if (serverNameFilled && serverIPFilled) {
add(addNewServer);
addNewServer.setSize(100, 25);
addNewServer.setLocation(serverIP.getX(), serverIP.getY() + 35);
addNewServer.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
}
}
});
}
});
add(settings);
settings.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
remove(createWorld);
remove(addServer);
remove(worldName);
remove(serverName);
remove(serverIP);
remove(addNewWorld);
remove(addNewServer);
repaint();
add(sound);
sound.setSize(settings.getWidth(), settings.getHeight());
sound.setLocation(settings.getX() + (settings.getWidth() / 2) + 5, settings.getY() + 35);
sound.setOpaque(false);
sound.setMinimum(0);
sound.setMaximum(100);
sound.setValueIsAdjusting(true);
sound.setValue(soundLevel);
sound.setToolTipText("Audio: " + soundLevel + "%");
sound.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
soundLevel = sound.getValue();
sound.setToolTipText("Audio: " + soundLevel + "%");
prefs.putInt("SOUND_LEVEL", soundLevel);
}
});
add(light);
light.setSize(settings.getWidth(), settings.getHeight());
light.setLocation(sound.getX(), sound.getY() + 35);
light.setOpaque(false);
light.setMinimum(50);
light.setMaximum(150);
light.setValueIsAdjusting(true);
light.setValue(lightLevel);
light.setToolTipText("Brightness: " + lightLevel + "%");
light.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent e) {
lightLevel = light.getValue();
light.setToolTipText("Brightness: " + lightLevel + "%");
prefs.putInt("LIGHT_LEVEL", lightLevel);
}
});
add(fullscreen);
fullscreen.setSize(100, settings.getHeight());
fullscreen.setLocation(settings.getX() + (settings.getWidth() / 2) - 50, light.getY() + 35);
fullscreen.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
MainMenu.isFullscreen = true;
}
});
}
});
add(quit);
quit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(ABORT);
}
});
}
}
}
我知道这是很多代码可以浏览，但我只是简单地难以理解。
答案 0 :(得分：1)
在swing中添加UI组件时，您需要调用组件的revalidate方法才能使更改生效。
答案 1 :(得分：0)
无法准确判断您在做什么，但我不确定您是否应该不断删除/添加单个组件。
也许您应该使用Card Layout，这将允许您根据用户请求的特定功能删除/添加面板。