java - 如何在Java中创建一个空的KeyEvent和SetKeyCode(keyCode)？

Question

在我的项目中，我尝试从发送 writeInt(e.getKeyCode()) 的另一台计算机接收 dataInputStream，即 readInt() 到这台计算机，但是当我收到 keyCode 时，如何将其放入 KeyEvent 对象中？

这是我的编码的一部分:

KeyEvent enemyKey;
try{
  key = inputFromClient.readInt();
  if(key!=0) {
    enemyKey.setKeyCode(key);
    player2.keyPressed(enemyKey);
  }
}catch(Exception ex){
  System.out.println(ex);
}

通过执行上面的代码，我得到 NullPointerException，因为 KeyEvent heavenlyKey 为 null。我该如何解决这个问题？

Answer 1

您还没有初始化KeyEventenemyKey;您可以使用此构造函数初始化它

public KeyEvent(Component source,
    int id,
    long when,
    int modifiers,
    int keyCode,
    char keyChar)

source - The Component that originated the event

id - An integer indicating the type of event. For information on allowable values, see the class description for KeyEvent

when - A long integer that specifies the time the event occurred. Passing negative or zero value is not recommended

modifiers - The modifier keys down during event (shift, ctrl, alt, meta). Passing negative value is not recommended. Zero value means that no modifiers were passed. Use either an extended _DOWN_MASK or old _MASK modifiers, however do not mix models in the one event. The extended modifiers are preferred for using

keyCode - The integer code for an actual key, or VK_UNDEFINED (for a key-typed event)

keyChar - The Unicode character generated by this event, or CHAR_UNDEFINED (for key-pressed and key-released events which do not map to a valid Unicode character)

参见KeyEvent javadoc有关可以传递给构造函数的值的更多信息

此外，请查看 Javabeans