Get the VK int from an arbitrary char in java

Question

How do you get the VK code from a char that is a letter? It seems like you should be able to do something like javax.swing.KeyStroke.getKeyStroke(\'c\').getKeyCode()<

Answer 1

I don't think there is an easy answer for this.

First realize that java has two byte chars and not nearly 2^16 KeyEvent.VK_'s defined. So there are going to be chars for which no KeyEvent can be generated to get that output.

Also, C and c and Ç and ç all have the same KeyEvent.getKeyCode() == KeyEvent.VK_C.

Answer 2

Maybe this ugly hack:

Map<String, Integer> keyTextToCode = new HashMap<String, Integer>(256);
Field[] fields = KeyEvent.class.getDeclaredFields();
for (Field field : fields) {
    String name = field.getName();
    if (name.startsWith("VK_")) {
        keyTextToCode.put(name.substring("VK_".length()).toUpperCase(),
                          field.getInt(null));
    }
}

keyTextToCode would then contain the mapping from strings (e.g. "A" or "PAGE_UP") to vk codes.

Answer 3

If your primary goal is to write out the letters as fast as possible, you can do what I did which was to write a string to the clipboard, then just use the Robot class to enter Ctrl+V.

static void type(String s) {
    Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(s), null);
    robot.setAutoDelay(30);
    robot.keyPress(VK_CONTROL);
    robot.keyPress(VK_V);
    robot.keyRelease(VK_CONTROL);
    robot.keyRelease(VK_V);
}

There are some other features in the system clipboard that could allow you to save and restore any data on the clipboard, in case you needed to. As well, you if you wanted to control the speed between each character, you could put each letter on the clipboard one at a time, with a robot.delay(n); in between them, using a foreach loop.

Answer 4

The answer of Adam Paynter (answered to the question Convert String to KeyEvents) should also work here. The simple but working idea is to have a big switch like the following:

public void type(char character) {
    switch (character) {
    case 'a': doType(VK_A); break;
    case 'b': doType(VK_B); break;
    case 'c': doType(VK_C); break;
    case 'd': doType(VK_D); break;
    case 'e': doType(VK_E); break;
    // ...
    case 'A': doType(VK_SHIFT, VK_A); break;
    case 'B': doType(VK_SHIFT, VK_B); break;
    case 'C': doType(VK_SHIFT, VK_C); break;
    // ...
    }
}

See the original answer for the whole listing (including surrounding utility class).

Answer 5

There are 2 ways I found:

A. Use a workaround of JButton.setMnemonic, getMnemonic:

javax.swing.JButton but = new javax.swing.JButton();
but.setMnemonic(charVkValue);
int intVkValue = but.getMnemonic());

B. Download open jdk source and see its AbstractButton.setMnemonic(char) method. This code is licensed under GPL2, but these 4 lines do generally the same as the answer with "keyPress(48+(int)c)".

http://www.java2s.com/Open-Source/Java-Document/6.0-JDK-Core/swing/javax/swing/AbstractButton.java.htm

Answer 6

AWTKeyStroke.getAWTKeyStroke('c').getKeyCode();

Slight clarification of Pace's answer. It should be single quotes (representing a character), not double quotes (representing a string).

Using double quotes will throw a java.lang.IllegalArgumentException (String formatted incorrectly).