Simultaneous key press in Processing

** Introduction **

For super beginners. You can also press and hold it for a long time.

** How to do **

The keyPressed function / keyReleased function determines whether each key is pressed or released.

//Stores the input status of each key
boolean right, left, down, up;

void keyPressed() {
  if (keyCode == RIGHT) right = true;
  if (keyCode == LEFT)  left  = true;
  if (keyCode == DOWN)  down  = true;
  if (keyCode == UP)    up    = true;
}

void keyReleased() {
  if (keyCode == RIGHT) right = false;
  if (keyCode == LEFT)  left  = false;
  if (keyCode == DOWN)  down  = false;
  if (keyCode == UP)    up    = false;
}

Simultaneous press / long press processing can be performed with just this. later

python

  if (right) {
    /*Processing when the right key is pressed*/
  }
  if (left) {
    /*Processing when the left key is pressed*/
  }
  if (down) {
    /*Processing when the down key is pressed*/
  }
  if (up) {
    /*Processing when the up key is pressed*/
  }

You can divide the processing for each key like this.

However, this is not very smart, so let's manage the input state collectively with HashMap.

python

// keyCode(int type)And its input state(boolean type)Store
HashMap<Integer, Boolean> key = new HashMap<Integer, Boolean>();

void keyPressed() {
  key.put(keyCode, true);
}

void keyReleased() {
  key.put(keyCode, false);
}

In addition, create a KeyState class that manages the input state.

KeyState.pde

static class KeyState {
  static HashMap<Integer, Boolean> key;
  
  //Initialization of input state
  static void initialize() {
    key = new HashMap<Integer, Boolean>();

    key.put(RIGHT, false);
    key.put(LEFT,  false);
    key.put(UP,    false);
    key.put(DOWN,  false);
  }
  
  //Receives and updates keyCode and its input status
  static void putState(int code, boolean state) {
    key.put(code, state);
  }
  
  //Receives keyCode and returns its input status
  static boolean getState(int code) {
    return key.get(code);
  }
}

When getting the input status, it looks like this

main.pde

void setup() {
  KeyState.initialize();
}

void draw() {
  if (keyState.getState(RIGHT)) {
    /*Processing when the right key is pressed*/
  }
  if (keyState.getState(LEFT)) {
    /*Processing when the left key is pressed*/
  }
  if (keyState.getState(DOWN)) {
    /*Processing when the down key is pressed*/
  }
  if (keyState.getState(UP)) {
    /*Processing when the up key is pressed*/
  }
}

void keyPressed() {
  KeyState.putState(keyCode, true);
}

void keyReleased() {
  KeyState.putState(keyCode, false);
}

Thank you for your support.

in conclusion

The direction key is ** keyCode (int type) **, but Tab and Enter are stored in ** key (char type) **, so you need to make another effort.