Substring index out of bounds in java

Question

I am writing a simple code that displays only the name of the processes which are of "console" type using tasklist in java.

I am unable to do so because of the string index out of bounds error in this code. I used index 36 to 43 because in these I got the process type during output of the code where we print all the processes using tasklist. Same goes for 0 to 30 for process name.

Please help me with this.

import java.io.*;
 public class process_name
  {
    public static void main(String []args)
     {
        try {
             int i;
              String line,pn,pt;
              pn="";
              Process p = Runtime.getRuntime().exec(System.getenv("windir") +"\\system32\\"+"tasklist.exe");

              BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));

            while ((line = input.readLine()) != null)
            {
              pt=line.substring(36,43);
              if(pt.equals("Console")) 
              {
                 pn=line.substring(0,30);
                 System.out.println(pn);
              }
              System.out.println();
             }
        input.close();
       }
     catch (Exception err) 
     {
       err.printStackTrace();
     }
}

}

Answer 1

Just to avoid the Index to be out of bounds, I should check first if the current line contains the word "Console" and also check the length:

import java.io.*;
 public class Main
  {
    public static void main(String []args)
     {
        try {
             int i;
              String line,pn,pt;
              pn="";
              Process p = Runtime.getRuntime().exec(System.getenv("windir") +"\\system32\\"+"tasklist.exe");


              BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));

            while ((line = input.readLine()) != null)
            {
               if(line.contains("Console"))
               {
                   if(line.length()>30){
                   pn=line.substring(0,30); System.out.println(pn);}
            }
              System.out.println();
             }
        input.close();
       }
     catch (Exception err) 
     {
       err.printStackTrace();
     }
}}

Answer 2

Try checking the length of that line. It might not be long enough which causes an out of bounds error as it is not long enough.

 System.out.println(line.length());

or you could check the length of the line before the call

 if (line.length() >= 43){
 ....

Answer 3

What I can see, tasklist prints at the beginning an empty line. An easy check would be if (!line.contains("Console")) continue; at the beginning of the while loop. With that, you skip every line, which does not contain the string Console.