CODEWITHSUNDEEP
javaandroidstring
user4336477
user4336477

Reputation: 9

String exception

I am getting a string index out of bound exception while decoding string pattern a-695b-36c158d-666e-1326f144. I want to extract values between a & b, b & c, c & d.

This code prints values sometimes properly but fails sometimes. I dont understand why this exception occurs sometimes.

Below is my code:

       public void run() {
        Log.i(TAG, "BEGIN mConnectedThread");
        byte[] buffer = new byte[128];
        int bytes;

        // Keep listening to the InputStream while connected
        while (true) {
            try {

                // Read from the InputStream
                bytes = mmInStream.read(buffer);
                int buflen=buffer.length;
                String str = new String(buffer, "UTF-8"); // prints character
                Log.d("Data Transmitted", str);
                int spaceIndex = str.indexOf(" ");
                if (spaceIndex != -1)
                {
                    str = str.substring(0, spaceIndex);
                }
                Log.d("Data Edited", str);

                boolean v1=str.contains("a");                   
                boolean v2=str.contains("b");
                boolean v3=str.contains("c");
                boolean v4=str.contains("d");
                if(v1==true && v2==true && v3==true && v4==true){

                mEmulatorView.write(buffer, bytes);
                String op1=str.substring(str.indexOf("a")+1, str.indexOf("b"));
               Log.d("output", op1);
                String op2=str.substring(str.indexOf("b")+1, str.indexOf("c"));
               Log.d("output", op2);
                String op3=str.substring(str.indexOf("c")+1, str.indexOf("d"));
              Log.d("output", op3);

                }
                else{

                mEmulatorView.write(buffer, bytes);
                }
                // Send the obtained bytes to the UI Activity
                //mHandler.obtainMessage(BlueTerm.MESSAGE_READ, bytes, -1, buffer).sendToTarget();
            } catch (IOException e) {
                Log.e(TAG, "disconnected", e);
                connectionLost();
                break;
            }
        }
    }

I always get data in this form: 12-12 12:43:54.681: D/Data Transmitted(23778): a-695b-36c158d-666e-1326f144

12-12 12:43:54.681: D/Data Transmitted(23778): a-684b-75c35d-659e-838f119

12-12 12:43:54.681: D/Data Transmitted(23778): a-674b-353c238d-658e-556f148

Exception: 

>  E/AndroidRuntime(23778): FATAL EXCEPTION: Thread-2313 
> E/AndroidRuntime(23778): Process: es.pymasde.blueterm, PID: 23778 
> E/AndroidRuntime(23778):
> java.lang.StringIndexOutOfBoundsException:length=128; regionStart=29;
> regionLength=-26  E/AndroidRuntime(23778):    at
> java.lang.String.startEndAndLength(String.java:588) 
> E/AndroidRuntime(23778):  at
> java.lang.String.substring(String.java:1475)

Upvotes: 0

Views: 142

Answers (3)

suyog patil
suyog patil

Reputation: 414

You can use regex to parse string : - 

String str  = "a-695b-36c158d-666e-1326f144";
boolean v1=str.contains("a");                   
boolean v2=str.contains("b");
boolean v3=str.contains("c");
boolean v4=str.contains("d");
if(v1==true && v2==true && v3==true && v4==true){
  String aToB = str.replaceAll(".*a", "").replaceAll("b.*", "");
  System.out.println(aToB);
  String bToc = str.replaceAll(".*c", "").replaceAll("d.*", "");
  System.out.println(bToc);
  String cTod = str.replaceAll(".*d", "").replaceAll("e.*", "");
  System.out.println(cTod);

}

Upvotes: 0

Rustam
Rustam

Reputation: 6515

try like this

public static void main(String[] args) {
    String str="a-695b-36c158d-666e-1326f144";
    int aIndex=str.indexOf('a');
    int bIndex=str.indexOf('b');
    int cIndex=str.indexOf('c');
    int dIndex=str.indexOf('d');


    if(aIndex>-1 && bIndex>-1 && cIndex>-1&& dIndex>-1){
        System.out.println("op1 -->"+str.substring(aIndex+1,bIndex));
        System.out.println("op2 -->"+str.substring(bIndex+1,cIndex));
        System.out.println("op3 -->"+str.substring(cIndex+1,dIndex));
    }else{
        System.out.println("invalid format");
    }
}

Note :- Make sure the order of alphabets (a,b,c...) are in ascending order. IOBE occurs when the length of substring you are trying to access becomes -ve i.e (endIndex-beginIndex) becomes -ve.

Upvotes: 0

Dawood ibn Kareem
Dawood ibn Kareem

Reputation: 79857

You'll get that exception if the indexes of a, b, c, d are not in the expected order.

For example if the first index of a is AFTER the first index of b, then the expression str.substring(str.indexOf("a")+1, str.indexOf("b")) will throw this exception, as described in the Javadoc for the substring method, which promises ...

IndexOutOfBoundsException - if the beginIndex is negative, or endIndex is larger than the length of this String object, or beginIndex is larger than endIndex..

Upvotes: 1

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