Processingで複数のキーが押されたときの挙動

KeyState.pde

public class KeyState{
  HashMap<Integer, Boolean> Key;
  
  KeyState(){
    this.Initialize();
  }
  
  void Initialize(){
    this.Key = new HashMap<Integer, Boolean>();
    
    this.Key.put(RIGHT, false);
    this.Key.put(LEFT, false);
    this.Key.put(UP, false);
    this.Key.put(DOWN, false);
    this.Key.put(ALT, false);
    this.Key.put(SHIFT, false);
    this.Key.put(CONTROL, false);
  }
  boolean getState(int code){
    return this.Key.get(code);
  }
  
  void setState(int code, boolean state){
    this.Key.put(code, state);
  }
}

main.pde

KeyState keyState;
PImage img;
PFont f;

void setup() {
  
  keyState = new KeyState();
  keyState.Initialize();
  
  size(1600,900, P3D);
  
  f = createFont("Avenir-Light-48.vlw", 48);
  textFont(f);
  textAlign(CENTER, CENTER);
  
}

void draw(){
  background(0);
  if(keyState.getState(RIGHT) == true) {
    text('R', width/2, height/2);
  }
  if(keyState.getState(LEFT) == true) {
    text('L', width/2, height/2);
  }
  if(keyState.getState(DOWN) == true) {
    text('D', width/2, height/2);
  }
  if(keyState.getState(UP) == true) {
    text('U', width/2, height/2);
  }
  if(keyState.getState(SHIFT) == true) {
    text('S', width/2, height/2);
  }
  
  image(canvas, 0, 0);
  server.sendImage(canvas);
}

void keyPressed(){
  keyState.setState(keyCode, true);
}

void keyReleased(){
  keyState.setState(keyCode, false);
}