Comparing serial data with if statements in processing

Projects Programming
1

Hi , I have a little problem. So I'm trying to make a space invaders type game with light sensors as controls. Whenever the the sensor's input drops below 500 (because you covered it) the arduino prints a word corresponding with the sensor you covered. Now in processing I read the incoming serial data and run a function based on that.

Here's the processing code for the filtering function:

void serialEvent(Serial p){
    input = p.readStringUntil('\n');

    if(input == null){
        println(input);
    }else{
      println("not null");
      if(input.equals("left")){
        println("LEFT");
        spaceship.move("left");
      }
      if(input == ("right")){
        println("RIGHT");
        spaceship.move("right");    
      }
      if(input == ("shoot")){
        println("SHOOT");
        spaceship.shoot();
      }
    }
}

And here's the arduino code:

#define led1 12
#define led2 11
#define led3 10
#define ldr1 A0
#define ldr2 A1
#define ldr3 A2

void setup() {
  // put your setup code here, to run once:
  pinMode(led1, OUTPUT);      
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  digitalWrite(led1, HIGH);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, HIGH);
  Serial.begin(9600);

}

void loop() {

  // put your main code here, to run repeatedly:
  float readldr1 = analogRead(ldr1);
  float readldr2 = analogRead(ldr2);
  float readldr3 = analogRead(ldr3);


  if(readldr1 > 500){
    Serial.println("right");  
  }else{
    Serial.println("empty");
  }

  if(readldr2 > 500){
    Serial.println("shoot");
  }else{
    Serial.println("empty");
  }

  if(readldr3 > 500){
    Serial.println("left");
  }else{
    Serial.println("empty");
  }
}

In the Serial Monitor, I receive all three left, right and shoot. In the console window of processing, I only get null and not null. So it doesn't compare correctly to the if statements inside the not null statement. What am I doing wrong?

ps.: I have noticed that when I print the input variable i get for example:

"right

"

instead of "right"

Also all the other code works because the game ran perfectly when I used keypresses instead.

Can someone please help?

Thanks in advance,
Gyut

2

.println() may be sending a \r\n at the end of the line, in which case reading the input will result in 'left\r' as your string. You can check this.

I don't use Strings, but if there is a .contains method you can use instead of .equals this may be a safer option.

3

thank you sir! You just saved my finals project!