Java - java.lang.StringIndexOutOfBoundsException: String index out of range: 11

Question

I'm stuck with this and can't find a solution. Get error of Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 11.

Can anyone help to solve this? My code:

public static void main(String[] args) {
    try {
        Scanner sc = new Scanner(new File("Testing.txt"));
        int i = 0;

        while(sc.hasNext()){
            String line = sc.nextLine();
            char needle = line.charAt(i);

            while(i < line.length()){
                if(Character.isUpperCase(needle)) {
                    while(needle != ' '){
                        System.out.print(needle);
                        i++;
                        needle = line.charAt(i);
                    }
                    System.out.println(needle);
                }
                else{
                    i++;
                    needle = line.charAt(i);
               }
            }
        }
    } 
    catch (FileNotFoundException e) {
        System.out.println(e.getMessage());
    }
}

I'm trying to get all the strings that contains capital letter from the input text file. E.g. input text file contains "Kenny and I are eating in the Restaurant Yummy.". The output will be "Kenny, I, Restaurant, Yummy". — K.W
– K.W, Commented Mar 13, 2017 at 8:40
use split to split your line into word and test the first char to see if starts with uppercase — Scary Wombat
– Scary Wombat, Commented Mar 13, 2017 at 8:42
K.W I have added an answer showing you how. Alot cleaner and easier to understand I think — Scary Wombat
– Scary Wombat, Commented Mar 14, 2017 at 0:50

Steve · Accepted Answer · 2017-03-13 08:24:56Z

1

My assumption is that your error would be here;

                i++;
                needle = line.charAt(i);

and

                while(needle != ' '){
                    System.out.print(needle);
                    i++;
                    needle = line.charAt(i);
                }

As you are increasing the index without checking if the index exists.

answered Mar 13, 2017 at 8:24

Steve

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2 Comments

K.W Over a year ago

Any idea of how to fix this? How to check whether if the index is exists from the above code?

Steve Over a year ago

Something like if(i < line.length()), as you have elsewhere.

Scary Wombat · Accepted Answer · 2017-03-14 00:49:31Z

0

As per my above comment, it will be easuer to use the String split method. Of course input can be replaced with text from the file, and use of expectedResult and testing that the output equals that is purely optional

  public static void main(String[] args)
  {

      String input = "Kenny and I are eating in the Restaurant Yummy";
      String expectedResult = "Kenny, I, Restaurant, Yummy";
      String arr [] = input.split (" ");

      StringBuilder out = new StringBuilder();
      for (int i = 0; i < arr.length; i++) {
          if (Character.isUpperCase(arr[i].charAt(0))) {
              out.append(arr[i]).append(", ");
          }
      }

      if (out.length() > 1) {
          out.setLength(out.length() -2);
      }

      System.out.println (out);
      assert (expectedResult.equals(out.toString()));

  }

output

Kenny, I, Restaurant, Yummy

edited Mar 14, 2017 at 0:49

answered Mar 13, 2017 at 8:01

Scary Wombat

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2 Comments

K.W Over a year ago

May I know what is this line do? if (out.length() > 1) { out.setLength(out.length() -2); }

Scary Wombat Over a year ago

because we are appending ", " to every occurrence, we want to remove the last one.

anacron · Accepted Answer · 2017-03-13 09:39:27Z

0

I'm not sure what you are trying to achieve. But from your error, I can say that you are trying to increment the index counter and then trying to access the element in your String.

Inside your while loop and the else block, you have these statements:

i++;
needle = line.charAt(i);

Change them both to:

needle = line.charAt(i);
i++;

And your code will run without the said exception.

Update

I did the changes mentioned above, and made a couple of changes.

Include the declaration for int i=0; inside the first while loop. This is needed for more than one line in the text file.
Include the declaration char needle = line.charAt(i); statement inside the second while loop as you need to initialize needle for each line.

try (Scanner sc = new Scanner(new File("Testing.txt"))) {

    while (sc.hasNext()) {
        String line = sc.nextLine();
        int i = 0;

        while (i < line.length()) {
            char needle = line.charAt(i);
            if (Character.isUpperCase(needle)) {
                while (needle != ' ' && i < line.length()) {
                    needle = line.charAt(i);
                    if(needle != ' '){
                        System.out.print(needle);
                    }
                    i++;
                }
                if(i < line.length()) {
                    System.out.print(", ");
                }
            } else {
                needle = line.charAt(i);
                i++;
            }
        }
        System.out.println();
    }
} catch (FileNotFoundException e) {
    System.out.println(e.getMessage());
}

It prints the following output:

Kenny, I, Restaurant, Yummy

Hope this helps!

edited Mar 13, 2017 at 9:39

answered Mar 13, 2017 at 8:24

anacron

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1 Comment

K.W Over a year ago

I'm trying to get all the strings that contains capital letter from the input text file. E.g. input text file contains "Kenny and I are eating in the Restaurant Yummy.". The output will be "Kenny, I, Restaurant, Yummy". I have try to change them both according to the solution you suggest, but still getting the same error.

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