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

Question

In my project, I'm trying to receive a dataInputStream which is readInt() from another computer that sends writeInt(e.getKeyCode()) to this computer, but when I receives the keyCode , how do I put it into a KeyEvent object?

Here's a part of my coding:

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

By executing the code above, I get NullPointerException because KeyEvent enemyKey is null . What can I do to resolve this issue?

Answer 1

You haven't initialized KeyEvent enemyKey; You can initialize it with this constructor

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)

See KeyEvent javadoc for more information on values you can pass to the constructor

Also, take a look at Javabeans