抛出自定义异常（如果是for循环）

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.

Answer 1

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();
}

Answer 2

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();
}

Answer 3

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?

Answer 4

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();

    }

Answer 5

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.

Answer 6

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 ? .