Java中键盘事件的怪异行为

Question

When I press "Delete" button on the keyboard, program gets three events - KEY_PRESSED , KEY_TYPED , and KEY_RELEASED . The problem is, in KEY_PRESSED and KEY_RELEASED , parameter "keyCode" is set, but in the KEY_TYPED it is not (in fact, there no meaningful info in that event). With F5 key, it is even funnier - KEY_PRESSED and KEY_RELEASED are registered, but KEY_TYPED never occurs.

The listener was added via Toolkit.getDefaultToolkit().addAWTEventListener() . Using JDK 6.26.

What could be my problem?

EDIT: Here are the events that happen when Delete key is pressed:

 java.awt.event.KeyEvent[KEY_PRESSED,keyCode=127,keyText=Delete,keyChar=Delete,keyLocation=KEY_LOCATION_STANDARD,rawCode=119,primaryLevelUnicode=127,scancode=0] on javax.swing.JButton[,0,0,61x30,alignmentX=0.0,alignmentY=0.5,border=javax.swing.plaf.synth.SynthBorder@50f38cf0,flags=288,maximumSize=,minimumSize=,preferredSize=,defaultIcon=javax.swing.ImageIcon@6ae2d0b2,disabledIcon=,disabledSelectedIcon=,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],paintBorder=true,paintFocus=true,pressedIcon=,rolloverEnabled=true,rolloverIcon=,rolloverSelectedIcon=,selectedIcon=,text=SVG,defaultCapable=false]
 java.awt.event.KeyEvent[KEY_TYPED,keyCode=0,keyText=Unknown keyCode: 0x0,keyChar=Delete,keyLocation=KEY_LOCATION_UNKNOWN,rawCode=0,primaryLevelUnicode=127,scancode=0] on javax.swing.JButton[,0,0,61x30,alignmentX=0.0,alignmentY=0.5,border=javax.swing.plaf.synth.SynthBorder@50f38cf0,flags=288,maximumSize=,minimumSize=,preferredSize=,defaultIcon=javax.swing.ImageIcon@6ae2d0b2,disabledIcon=,disabledSelectedIcon=,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],paintBorder=true,paintFocus=true,pressedIcon=,rolloverEnabled=true,rolloverIcon=,rolloverSelectedIcon=,selectedIcon=,text=SVG,defaultCapable=false]
 java.awt.event.KeyEvent[KEY_RELEASED,keyCode=127,keyText=Delete,keyChar=Delete,keyLocation=KEY_LOCATION_STANDARD,rawCode=119,primaryLevelUnicode=127,scancode=0] on javax.swing.JButton[,0,0,61x30,alignmentX=0.0,alignmentY=0.5,border=javax.swing.plaf.synth.SynthBorder@50f38cf0,flags=288,maximumSize=,minimumSize=,preferredSize=,defaultIcon=javax.swing.ImageIcon@6ae2d0b2,disabledIcon=,disabledSelectedIcon=,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],paintBorder=true,paintFocus=true,pressedIcon=,rolloverEnabled=true,rolloverIcon=,rolloverSelectedIcon=,selectedIcon=,text=SVG,defaultCapable=false]

Answer 1

• better would be implements KeyBindings

• part of keyboard are reserved Keys for built-in JComponent funcionality, more informations from @camickrs UIManager Defaults

• depends of reason(s) why you needed implents KeyListener, because for there are lots of another Listeners for various JComponent, that should be filtering or register text changes inside

• some of JComponent Models generated Events from Mouse and Keyboard input

Answer 2

Key typed events ALWAYS generate '0' as the key code. Look up the method getKeyChar() instead, or (as has been suggested) listen for keyReleased() instead. getKeyChar(): http://goo.gl/ajH03

Answer 3

From the JavaDoc The "key typed" event. This event is generated when a character is entered. In the simplest case, it is produced by a single key press. Often, however, characters are produced by series of key presses, and the mapping from key pressed events to key typed events may be many-to-one or many-to-many. The "key typed" event. This event is generated when a character is entered. In the simplest case, it is produced by a single key press. Often, however, characters are produced by series of key presses, and the mapping from key pressed events to key typed events may be many-to-one or many-to-many.

You are trying to get the F5 key which is probably not registered as a character being entered. By using the KEY_RELEASED you will consistently get the result you are looking for and the API is behaving as expected.