Thread: Having problems with String out of bounds errors

Ok, well I am making a program which takes input, changes all multiple blanks into a single blank space, and creates a new line after a sentence is declared. A sentence will be declared by finding where the String has a "! . or ?" character followed by a blank space. It will also capitalize the first letter of the sentences.

For example, if the user entered:

this is an. example of desired?input! hurray.

The output would be:

This is an.
Example of desired?input!
Hurray.

So, I created a parseSentence() method to do the conversions required for me, but I keep running into an out of bounds error.

First, here is the method:

public String parseSentence(String sent) {
    	String temp;
    	for (int x = 0; x <= sent.length(); x ++) {
    		if ((sent.indexOf(sent.charAt(x)) + 1) != sent.length()){
    			if ((sent.charAt(x) & sent.charAt(x + 1)) == ' ') {
    				temp = sent.charAt(x + 1) + "";
    				sent = sent.replaceFirst(temp, "");
    			}
    			if (((sent.charAt(x) == '.') || (sent.charAt(x) == '!') || (sent.charAt(x) == '?')) & (sent.charAt(x + 1) == ' ')) {
    				temp = sent.charAt(x + 1) + "";
    				sent = sent.replaceFirst(temp, "\n");
    				sent = sent.replace(sent.charAt(x + 2), Character.toUpperCase(sent.charAt(x + 2)));
    			}
    		}
    	}
    	return sent;
    }

And this is the error after the input:

Please enter a sentence:
this    program    processes.     text files and creates! a  new  file?with * the       following.
[B]Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 75
    at java.lang.String.charAt(String.java:686)
    at TextFileProcessorDemo.parseSentence(TextFileProcessorDemo.java:31)
    at TextFileProcessor.main(TextFileProcessor.java:36[/B])

I thought it might have something to do with the loop executing towards the end of the String, and when charAt(x + 1) is trying to be found, there is nothing in that index so it would give the error. I tried to solve this by adding the first if statement, which I meant to make the loop essentially stop if the current value of x is equal to the length of the String. Though I know this would only be a partial fix for the (x + 1) parameters, and not the (x + 2) later on, but at least I was trying to make headway.

However, that fix still didn't solve my problem.

Any ideas?

Thanks!

Hello, the thing is that when you are playing with the individual characters of a string you need to remember that the charAt position is a zero based index.

Therefore this wont really work.

x <= sent.length()

Because you are looping up until the length of the string. Lets say we have a string with a length of 5 characters and you loop from 0 to 5 inclusively and the charAt is a zero based index, when you reach x = 5 and you try to get charAt(5) you will get a StringOutofBoundsException because there is no index 5 because the fifth character is actually in index 4.

Example:

test
0123

The string above is of length 4 but the indexes only go to 3. To fix this you need to change your loop to only loop while x is lower than the length.

for (int x = 0; x < sent.length(); x ++) {

Now that will solve the immediate problem, however I've also noticed somewhere in your code where you do this.

sent.charAt(x + 1)

This will also give you a StringOutofBoundsException if x is the last index in the string because x + 1 will be outside of the scope or bounds.

I hope this gives you a clue on what you need to do to sort out your issues. If you still need to use the x + 1 check just do a check first to make sure that x isnt the last index.

// Json

Sorry for the delay, and thanks for the advice. I was able to get it to work, for the most part.

Now I have the problem that when multiple spaces are detected within the array, it seems to leave an extra space when changing one of them to a return character. For example when I type "test. sent." (with two spaces after the first period) I want it to put:

Test.
Sent.

But instead, I'm getting:

Test.
 sent.

Here is my revised method, if anyone can help, that would be much appreciated. Thanks!

    public char[] parseSentence(char[] sent) {
    	sent[0] = Character.toUpperCase(sent[0]);
    	for (int x = 0; x < sent.length; x ++) {
    		if (x != (sent.length - 1)){
    			if (((sent[x] == '.') || (sent[x] == '!') || (sent[x] == '?')) && (sent[x + 1] == ' ')) {
    				sent[x + 1] = '\n';
					if (sent[x + 2] == ' ')                // SEE NOTE
						sent[x + 2] = '\u0000';     // SEE NOTE
					sent[x + 2] = Character.toUpperCase(sent[x + 2]);
    			}
    			if ((sent[x] == ' ') && (sent[x + 1] == ' ')) {
    				sent[x] = '\u0000';
    			}
    		}
    	}
    	return sent;
    }

NOTE: The portion of code:

if (sent[x + 2] == ' ')
     sent[x + 2] = '\u0000';

is just something I threw in the try. It doesn't appear to have any effect on the program, but I was trying something at least. Thanks!