Arduino Bluetooth Robot for Android Device

1int motor1Pin1 = 3; // pin 2 on L293D IC
2int motor1Pin2 = 4; // pin  7 on L293D IC
3int enable1Pin = 6; // pin 1 on L293D IC
4int motor2Pin1 = 8;  // pin 10 on L293D IC
5int motor2Pin2 = 9; // pin 15 on L293D IC
6int enable2Pin  = 11; // pin 9 on L293D IC
7int state;
8int flag=0;        //makes sure that  the serial only prints once the state
9int stateStop=0;
10void setup() {
11    // sets the pins as outputs:
12    pinMode(motor1Pin1, OUTPUT);
13    pinMode(motor1Pin2,  OUTPUT);
14    pinMode(enable1Pin, OUTPUT);
15    pinMode(motor2Pin1, OUTPUT);
16    pinMode(motor2Pin2, OUTPUT);
17    pinMode(enable2Pin, OUTPUT);
18    // sets  enable1Pin and enable2Pin high so that motor can turn on:
19    digitalWrite(enable1Pin,  HIGH);
20    digitalWrite(enable2Pin, HIGH);
21    // initialize serial communication  at 9600 bits per second:
22    Serial.begin(9600);
23}
24
25void loop() {
26    //if some date is sent, reads it and saves in state
27    if(Serial.available()  > 0){     
28      state = Serial.read();   
29      flag=0;
30    }   
31    //  if the state is '1' the DC motor will go forward
32    if (state == '1') {
33        digitalWrite(motor1Pin1, HIGH);
34        digitalWrite(motor1Pin2, LOW);  
35        digitalWrite(motor2Pin1, LOW);
36        digitalWrite(motor2Pin2, HIGH);
37        if(flag == 0){
38          Serial.println("Go Forward!");
39          flag=1;
40        }
41    }
42    
43    // if the state is '2' the motor will turn left
44    else if (state == '2') {
45        digitalWrite(motor1Pin1, HIGH); 
46        digitalWrite(motor1Pin2,  LOW); 
47        digitalWrite(motor2Pin1, LOW);
48        digitalWrite(motor2Pin2,  LOW);
49        if(flag == 0){
50          Serial.println("Turn LEFT");
51          flag=1;
52        }
53        delay(1500);
54        state=3;
55        stateStop=1;
56    }
57    // if the state is '3' the motor will Stop
58    else if (state ==  '3' || stateStop == 1) {
59        digitalWrite(motor1Pin1, LOW); 
60        digitalWrite(motor1Pin2,  LOW); 
61        digitalWrite(motor2Pin1, LOW);
62        digitalWrite(motor2Pin2,  LOW);
63        if(flag == 0){
64          Serial.println("STOP!");
65          flag=1;
66        }
67        stateStop=0;
68    }
69    // if the state is '4' the motor  will turn right
70    else if (state == '4') {
71        digitalWrite(motor1Pin1,  LOW); 
72        digitalWrite(motor1Pin2, LOW); 
73        digitalWrite(motor2Pin1,  LOW);
74        digitalWrite(motor2Pin2, HIGH);
75        if(flag == 0){
76          Serial.println("Turn  RIGHT");
77          flag=1;
78        }
79        delay(1500);
80        state=3;
81        stateStop=1;
82    }
83    // if the state is '5' the motor will Reverse
84    else if (state == '5') {
85        digitalWrite(motor1Pin1, LOW); 
86        digitalWrite(motor1Pin2,  HIGH);
87        digitalWrite(motor2Pin1, HIGH);
88        digitalWrite(motor2Pin2,  LOW);
89        if(flag == 0){
90          Serial.println("Reverse!");
91          flag=1;
92        }
93    }
94    //For debugging purpose
95    //Serial.println(state);
96}