从 Class 参数实例化新对象
Instantiate new object from Class of parameter
我正在用几个顺序创建的 JFrame 构建一个游戏。对于其中两个帧（大厅和实际游戏帧），我将用户输入（例如 F11）用于全屏模式。要进入或离开全屏模式，我显然必须处理当前帧并创建一个新帧，因为 setUndecorated() 的设置只能在使帧可见之前设置。
由于 JFrames 中的其他 UI 元素会获得焦点，所以我必须使用键绑定。因此我做了一个 class 来进入或离开全屏模式。为了阐明 JFrame 是否应该全屏创建，我传递了一个 int windowState 作为参数。因为应该可以实例化两个不同的屏幕，所以我不能简单地调用 class 本身，而是需要查看传递给 Action 事件的框架。
这是我到目前为止尝试做的事情：
public class EnterFullscreen extends AbstractAction{
private static final long serialVersionUID = 1773898497666165938L;
private JFrame frame;
private Class<?> frameType;
private Constructor<?> c;
public EnterFullscreen(JFrame frame) {
this.frame = frame;
try {
frameType = frame.getClass();
c = frameType.getConstructor(String.class);
} catch (NoSuchMethodException | SecurityException e) {
e.printStackTrace();
}
}
@Override
public void actionPerformed(ActionEvent e) {
try {
frame.setVisible(false);
if (frame.isUndecorated()) {
c.newInstance(0);
} else {
c.newInstance(1);
}
frame.dispose();
} catch (InstantiationException | IllegalAccessException | IllegalArgumentException
| InvocationTargetException e1) {
e1.printStackTrace();
}
}
}
错误信息：
java.lang.NoSuchMethodException: de.munchkin.frontend.Lobby.<init>(java.lang.String)
at java.lang.Class.getConstructor0(Class.java:3082)
at java.lang.Class.getConstructor(Class.java:1825)
at de.munchkin.keybindings.EnterFullscreen.<init>(EnterFullscreen.java:24)
at de.munchkin.frontend.Lobby.<init>(Lobby.java:45)
at de.munchkin.frontend.MatchCreation.lambda(MatchCreation.java:169)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6539)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6304)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
at java.awt.Container.dispatchEventImpl(Container.java:2283)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access0(EventQueue.java:97)
at java.awt.EventQueue.run(EventQueue.java:709)
at java.awt.EventQueue.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue.run(EventQueue.java:733)
at java.awt.EventQueue.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at de.munchkin.keybindings.EnterFullscreen.actionPerformed(EnterFullscreen.java:40)
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1668)
at javax.swing.JComponent.processKeyBinding(JComponent.java:2882)
at javax.swing.JComponent.processKeyBindings(JComponent.java:2943)
at javax.swing.JComponent.processKeyEvent(JComponent.java:2845)
at java.awt.Component.processEvent(Component.java:6316)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:835)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1103)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:974)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:800)
at java.awt.Component.dispatchEventImpl(Component.java:4760)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access0(EventQueue.java:97)
at java.awt.EventQueue.run(EventQueue.java:709)
at java.awt.EventQueue.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue.run(EventQueue.java:733)
at java.awt.EventQueue.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
问题是我收到此错误但找不到问题所在，因为我认为我正在做关于该主题的大多数其他 SO 文章所描述的事情：
Article 1
等等
这些文章中描述的是我需要获取构造函数并对其调用 newInstance()，如果我没记错的话，我就是这样做的。
那么，我需要做些什么不同的事情才能让它发挥作用？我真的没有看到上面链接的其他 SO 帖子中提出的解决方案有什么不同。
堆栈跟踪显示您的 class Lobby 没有带有一个 String.
类型参数的构造函数
根据你的用法，如 c.newInstance(0)，我假设你的构造函数采用 int/Integer。
所以，你应该写：
c = frameType.getConstructor(Integer.class);
我正在用几个顺序创建的 JFrame 构建一个游戏。对于其中两个帧（大厅和实际游戏帧），我将用户输入（例如 F11）用于全屏模式。要进入或离开全屏模式，我显然必须处理当前帧并创建一个新帧，因为 setUndecorated() 的设置只能在使帧可见之前设置。
由于 JFrames 中的其他 UI 元素会获得焦点，所以我必须使用键绑定。因此我做了一个 class 来进入或离开全屏模式。为了阐明 JFrame 是否应该全屏创建，我传递了一个 int windowState 作为参数。因为应该可以实例化两个不同的屏幕，所以我不能简单地调用 class 本身，而是需要查看传递给 Action 事件的框架。
这是我到目前为止尝试做的事情：
public class EnterFullscreen extends AbstractAction{
private static final long serialVersionUID = 1773898497666165938L;
private JFrame frame;
private Class<?> frameType;
private Constructor<?> c;
public EnterFullscreen(JFrame frame) {
this.frame = frame;
try {
frameType = frame.getClass();
c = frameType.getConstructor(String.class);
} catch (NoSuchMethodException | SecurityException e) {
e.printStackTrace();
}
}
@Override
public void actionPerformed(ActionEvent e) {
try {
frame.setVisible(false);
if (frame.isUndecorated()) {
c.newInstance(0);
} else {
c.newInstance(1);
}
frame.dispose();
} catch (InstantiationException | IllegalAccessException | IllegalArgumentException
| InvocationTargetException e1) {
e1.printStackTrace();
}
}
}
错误信息：
java.lang.NoSuchMethodException: de.munchkin.frontend.Lobby.<init>(java.lang.String)
at java.lang.Class.getConstructor0(Class.java:3082)
at java.lang.Class.getConstructor(Class.java:1825)
at de.munchkin.keybindings.EnterFullscreen.<init>(EnterFullscreen.java:24)
at de.munchkin.frontend.Lobby.<init>(Lobby.java:45)
at de.munchkin.frontend.MatchCreation.lambda(MatchCreation.java:169)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6539)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6304)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4535)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
at java.awt.Container.dispatchEventImpl(Container.java:2283)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access0(EventQueue.java:97)
at java.awt.EventQueue.run(EventQueue.java:709)
at java.awt.EventQueue.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue.run(EventQueue.java:733)
at java.awt.EventQueue.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at de.munchkin.keybindings.EnterFullscreen.actionPerformed(EnterFullscreen.java:40)
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1668)
at javax.swing.JComponent.processKeyBinding(JComponent.java:2882)
at javax.swing.JComponent.processKeyBindings(JComponent.java:2943)
at javax.swing.JComponent.processKeyEvent(JComponent.java:2845)
at java.awt.Component.processEvent(Component.java:6316)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:835)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1103)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:974)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:800)
at java.awt.Component.dispatchEventImpl(Component.java:4760)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access0(EventQueue.java:97)
at java.awt.EventQueue.run(EventQueue.java:709)
at java.awt.EventQueue.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue.run(EventQueue.java:733)
at java.awt.EventQueue.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
问题是我收到此错误但找不到问题所在，因为我认为我正在做关于该主题的大多数其他 SO 文章所描述的事情：
Article 1
这些文章中描述的是我需要获取构造函数并对其调用 newInstance()，如果我没记错的话，我就是这样做的。
那么，我需要做些什么不同的事情才能让它发挥作用？我真的没有看到上面链接的其他 SO 帖子中提出的解决方案有什么不同。
堆栈跟踪显示您的 class Lobby 没有带有一个 String.
根据你的用法，如 c.newInstance(0)，我假设你的构造函数采用 int/Integer。
所以，你应该写：
c = frameType.getConstructor(Integer.class);