How to Simulate Keyboard Input in Java: A Simple Approach vs. Custom Key Handling

Simulating Keyboard Input from a String

Introduction:
In programming, it may be necessary to simulate text input using the keyboard for automated testing or other purposes. This involves converting a string into a series of key events that can be dispatched to an application. Here's how to achieve this using Java APIs.

Approach using Switch Statement:
A simple method is to use a glorified switch statement that directly maps characters to key codes. For each character in the input string, a corresponding key code is retrieved and the key press and release events are simulated using the Robot class.

Java Code for Switch Statement Approach:

<code class="java">import static java.awt.event.KeyEvent.*;

public class KeystrokeSimulator {

    public static void main(String[] args) {
        String input = "Example Keystrokes";
        int keycode;

        // Initialize the Robot for key event simulation
        Robot robot = new Robot();

        // Loop through each character
        for (char character : input.toCharArray()) {
            switch (character) {
                case 'a': keycode = VK_A; break;
                case 'b': keycode = VK_B; break;
                // ... continue for all characters
                default: keycode = 0; // Unknown character
            }

            if (keycode != 0) {
                robot.keyPress(keycode);
                robot.keyRelease(keycode);
            }
        }
    }
}</code>

Advanced Approach with Key Customization:
For scenarios where custom handling is required for certain characters, a more advanced approach can be taken. The base class can be extended and the type method can be overridden to account for special characters or custom key combinations.

Java Code for Advanced Customization:

<code class="java">import static java.awt.event.KeyEvent.*;

public class CustomKeystrokeSimulator extends KeystrokeSimulator {

    public CustomKeystrokeSimulator(Robot robot) {
        super(robot);
    }

    @Override
    public void type(char character) {
        super.type(character);
        // Custom handling for special characters or key combinations
        // (e.g., mapping '!' to Shift + '1')
    }
}</code>

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