Java Log File Reader, charAt() String index out of range

Question

I have a problem. I want to make a programm, that takes a Log File and parse it line for line.

A Log looks like this:

"2014-02-14 14:26:37,836 INFO [org.jboss.msc] (main) JBoss MSC version 1.0.4.GA-redhat-1"

My code:

 public static void main(String[] args) throws InterruptedException {
    try
    {
        String sCurrentLine;


        BufferedReader br = new BufferedReader(new FileReader("C:\\server.log"));            

        while ((sCurrentLine = br.readLine()) != null) {
            String datetime = "";
            String level = "";
            String category = "";
            String message = "";
            String output = "";

            if(sCurrentLine.length()<1){                    
            }
            else{
                if (sCurrentLine.charAt(4)=='-' && sCurrentLine.charAt(7)=='-' && sCurrentLine.charAt(13)==':' && sCurrentLine.charAt(16)==':'){
                    String[] leerzeichen = sCurrentLine.split(" ");
                    String[] leerzeichenz = sCurrentLine.split("  ");

                    datetime = leerzeichen[0] + " " + leerzeichen[1];
                    level = leerzeichen[2];
                    category = leerzeichen[4];

                    int arraylength = leerzeichen.length;

                    for (int l=5; l<arraylength; l++){
                        message = message.concat(leerzeichen[l] + " ");
                    }
                    output = datetime + level + category + message;
                } else {
                    message = message.concat(sCurrentLine);     
                    output += message;

                }
            }
           System.out.println(output);
        }


    } catch (IOException e) {
        e.printStackTrace();
    } 
}

The Program looks, if the beginning of the Line looks like this: 0000-00-00 00:00:00 If not, the Line is only a message in connection with the line before.

But I always get the Error:

 Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 4
at java.lang.String.charAt(String.java:658)
at javaapplication5.JavaApplication5.main(JavaApplication5.java:38)

But he reads some lines of the log. But not until the end of the log.

Can you help me? sorry for my English.

Answer 1

You have problem in line:

if (sCurrentLine.charAt(4)=='-' && sCurrentLine.charAt(7)=='-' && sCurrentLine.charAt(13)==':' && sCurrentLine.charAt(16)==':'){

You cannot assume that the line have at least 4, 7 or more characters.

Try changing it to this:

if (sCurrentLine.length() >= 16 && sCurrentLine.charAt(4)=='-' && sCurrentLine.charAt(7)=='-' && sCurrentLine.charAt(13)==':' && sCurrentLine.charAt(16)==':'){

Answer 2

The cause of error is quite straight forward; you first check if string has length > 1, and then directly ask for char at index 4 -- which is no guarantee to exists since all you know is thats length > 1.

Hence, add proper checking before trying to access char at index 4, and most of all, as said in comment by @VusP, add some print/debugging of the read string before trying to parse it.