How to Control AC Load With Bluetooth

1#define r1 5
2int relay1 = LOW;
3#define r2 6
4int relay2 = LOW;
5#define  r3 7
6int relay3 = LOW;
7#define r4 8
8int relay4 = LOW;
9
10void setup()  {
11Serial.begin(9600);
12    pinMode(r1, OUTPUT); 
13    pinMode(r2, OUTPUT);
14    pinMode(r3, OUTPUT); 
15    pinMode(r4, OUTPUT);
16 }
17
18void loop() {
19  // put your main code here, to run repeatedly:
20 if(Serial.available()>0) 
21   {     
22      char data= Serial.read(); // reading the data received from the  bluetooth module
23      switch(data)
24      {
25        case 'a':
26            digitalWrite(r1,0);
27            digitalWrite(r2,0);  //all off
28            digitalWrite(r3,0);
29            digitalWrite(r4,0);
30            delay(250);
31            break;        
32            case 'b':
33            relay1 = ~ relay1;
34            digitalWrite(r1,relay1);
35            delay(250);
36            break;
37            case 'c':
38            relay2  = ~ relay2;
39            digitalWrite(r2,relay2);
40            delay(250);
41            break;
42            case 'd':
43            relay3 = ~ relay3;
44            digitalWrite(r3,relay3);
45            delay(250);
46            break;
47            case 'e':
48            relay4 = ~ relay4;
49            digitalWrite(r4,relay4);
50            delay(250);
51            break;
52      }
53      Serial.println(data);
54   }
55   delay(50);
56}