Cannot extract a string from incoming message using prefix and suffix in android

Question

I have incoming message in two slightly different formats like:

1. "Info : STD ID2.7384733928374. PSSID, SSN:324920349023742903, END"
2. "Info : STD Z10 1234567890123 PSSID, SSN:12394847382940398433, END"

I can sucessfully extract string from the first format using below method:

String message = "Info : STD ID2.7384733928374. PSSID, SSN:324920349023742903, END";
    String prefix1 = "ID";
    String suffix1 = ".";
    String output1 = message.substring(message.indexOf(prefix1) + prefix1.length(), message.indexOf(suffix1));
    Log.d("Output1",  output1);
String prefix2 = ".";
    String suffix2 = ". PSSID";
    String output2 = message.substring(message.indexOf(prefix2) + prefix2.length(), message.indexOf(suffix2));
    Log.d("Output2", output2);
    // Output2: 7384733928374 (correct)

1. Output1: 2 (correct) and
2. Output2: 7384733928374 (correct)

But Cannot extract from the second format using the same method as above:

String message = "Info : STD Z10 1234567890123 PSSID, SSN:12394847382940398433, END";

    String prefix1 = "Z";
    String suffix1 = " ";
    String output1 = message.substring(message.indexOf(prefix1) + prefix1.length(), message.indexOf(suffix1));
    Log.d("Output1",  output1);

    String prefix2 = " ";
    String suffix2 = " PSSID";
    String output2 = message.substring(message.indexOf(prefix2) + prefix2.length(), message.indexOf(suffix2));
    Log.d("Output2", output2);

1. Output1: error java.lang.StringIndexOutOfBoundsException: length=65; regionStart=12; regionLength=-8
2. Output2 STD Z10 1234567890123 (wrong) correct output should be 1234567890123

Please help me how to extract the 10 and 1234567890123 from the second format?

Answer 1

You can use regex to match both situations:

    Pattern pattern = Pattern.compile("\\d+");
    Matcher matcher = pattern.matcher(message);

    matcher.find();
    System.out.println(matcher.group());
    matcher.find(matcher.end());
    System.out.println(matcher.group());