Throwing custom Exceptions, if for loop

Question

public class StringArray {
    private String strArr[];

    public StringArray(int capacity) {
       strArr = new String [capacity];
    }

    public int indexOf(String s) throws StringNotFoundException {
        for(int i=0;i<strArr.length ;++i) {
            if (strArr[i].equals(s)) {
                return i;
            } else {
                throw new StringNotFoundException();
            }
        }
    }
}

What I want to do is to return the index of the string I'm looking for if it's in the array, to throw an exception otherwise.

However Eclipse says I've got to return an int.

So should I just change the return type to void or are there other options?

StringNotFoundException is a custom exception I've made up.

return -1 or have your program exit if the index is crucial to the function of your program — turbo, Dec 13 '13 at 14:24
Also note that you will always throw an exception if the String you search is not in the first slot of you array. — Alexis C., Dec 13 '13 at 14:25
Work on your code formatting too...you're also missing the closing bracket for the `for` loop. — crush, Dec 13 '13 at 14:28
My question would be: why are you implementing a `StringArray`? — lucke84, Dec 13 '13 at 14:58

score 6 · Accepted Answer · answered Dec 13 '13 at 14:26

6

do like this

public int indexOf(String s) throws StringNotFoundException {
     for(int i=0;i<strArr.length ;++i) {
         if (strArr[i].equals(s)){
             return i;
         }
     }
     throw new StringNotFoundException();
}

answered Dec 13 '13 at 14:26

Prabhakaran Ramaswamy

25,706
10
57
64

score 4 · Answer 2 · answered Dec 13 '13 at 14:27

Why return -1 here? here is the code:

public int indexOf(String s) throws StringNotFoundException {
    for(int i=0; i<strArr.length ;++i) {
        if (strArr[i].equals(s)) {
            return i;
        }
    }
    throw new StringNotFoundException();
}

score 2 · Answer 3 · edited May 23 '17 at 11:49

The fact that you're not finding the String you're looking for is not enough to justify the usage of Exception. It's not an exceptional case, you know it's going to happen, you're saying that in your code.

Your code should reflect this. You should not return custom values, that is adding a meaning to things like -1 or the likes, which is not correct.

More on the subject: Should a retrieval method return 'null' or throw an exception when it can't produce the return value?

score 2 · Answer 4 · answered Dec 13 '13 at 14:26

You need to iterate through each string in the array and only if nothing matches, throw the exception.

I think this is what you want :

public int indexOf(String s) throws StringNotFoundException {
        for (int i = 0; i < strArr.length; ++i) {
            if (strArr[i].equals(s)) {
                return i;
            } 

        }
        throw new StringNotFoundException();

    }

score 0 · Answer 5 · answered Dec 13 '13 at 14:26

How about:

/** Returns index of String s in array strArr.  Returns -1 if String s is not found. */
public int indexOf(String s) {
        for(int i=0;i<strArr.length ;++i) {
            if (strArr[i].equals(s)){
             return i;
            }
        return -1;
}

Avoids using an exception altogether.

score 0 · Answer 6 · answered Dec 13 '13 at 14:38

0

Try this..

public int indexOf(String s) throws StringNotFoundException {

       int index = Arrays.binarySearch(strArr ,s);

        if( index > 0)
             return index;
        else
            throw new StringNotFoundException();
    }

Why you want to do this ? .

answered Dec 13 '13 at 14:38

HybrisHelp

5,518
2
27
65

That requires a sorted array. – zapl Dec 13 '13 at 14:41

Throwing custom Exceptions, if for loop

6 Answers6