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();
     }
}

}

can you print the line in console of editor and see if the line is expected, and also do you have empty line in the file that you are reading, did you cross check that? — pavan kumar, Nov 30 '19 at 09:42
You may use regex, seems that you're line is just not so long, print it, and you'll find — azro, Nov 30 '19 at 09:45
The first line of the tasklist output is empty, just skip the first line or check if the line is not empty — b.GHILAS, Nov 30 '19 at 10:56

score 2 · Answer 1 · answered Nov 30 '19 at 10:28

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){
 ....

answered Nov 30 '19 at 10:28

Ronnie Lightweightbaby Coleman

127
6

score 0 · Answer 2 · answered Nov 30 '19 at 10:38

0

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.

answered Nov 30 '19 at 10:38

Byte

55
1
8

score 0 · Accepted Answer · answered Nov 30 '19 at 10:40

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();
     }
}}

Substring index out of bounds in java

3 Answers3