How to use this Arduino code to control multiple different LEDs?

Question

I am making an Android-controlled LED system over Bluetooth but I need to use 4 LEDs. I have done Android app but I am not able to figure out this Arduino code. Can some please help me get this done?

char command;
String string;
boolean ledon = false;
#define led 5

void setup() {
  Serial.begin(9600);
  pinMode(led, OUTPUT);
}

void loop() {
  if (Serial.available() > 0) {
    string = "";
  }

  while(Serial.available() > 0) {
    command = ((byte)Serial.read());
    if(command == ':') {
      break;
    } else {
      string += command;
    }
    delay(1);
  }

  if(string == "TO") {
    ledOn();
    ledon = true;
  }

  if(string =="TF") {
    ledOff();
    ledon = false;
    Serial.println(string);
  }

  if ((string.toInt()>=0)&&(string.toInt()<=255)) {
    if (ledon==true) {
      analogWrite(led, string.toInt());
      Serial.println(string);
      delay(10);
    }
  }
}

void ledOn() {
  analogWrite(led, 255);
  delay(10);
}

void ledOff() {
  analogWrite(led, 0);
  delay(10);
}

Answer 1

Its better if you use SoftwareSerial for Bluetooth, so the native serial port can be used to debugging. But in case you doesn't need them:

uint8_t led[4] = {5,6,7,8}; // pin for LED 1,2,3,4
char command1,command2;
String string;
  void setup()
  {
    Serial.begin(9600);
    for (int i=0; i<4; i++)
        pinMode(led[i], OUTPUT); //set all LED pin as OUTPUT
  }

  void loop()
  {
    if (Serial.available() > 1) //run if 1 bit or more data received
    {
    string = "";
        command1 = Serial.read();
        command2 = Serial.read();
        switchled(command1-'0',command2-'0');
    string = command1+command2;
    }
    delay(1);
  }
void switchled(char pinLED,char statusLED)
{
    if (statusLED == 0 || statusLED == 1)
    digitalWrite(led[pinLED-1],statusLED);
    else
    digitalWrite(led[pinLED-1],!digitalRead(led[pinLED-1]));

    Serial.print("LED "); 
    Serial.print(pinLED); 
    Serial.print(" = "); 
    Serial.print(digitalRead(pinLED)); 
}

The code reads 2 byte of data, so if your phone sent "11" the 1st led will turned on, and "10" will turn the 1st led off. The first digit is the LED index (1/2/3/4) and the second digit is the LED state (0/1), other than that, the LED on selected index will be toggled;