Java Recursive Linear Search in array returned value problem

Question

I am using an recursive linear search algortihm. even the if condition is true it always returns null. If I don't put null it gives an error. I could not just figure out that how can I made proper. Thanks for help

private String findMinimumPricedHelper(String name, IMedia[] treeArray, int index) {
   if (some conditions) 
       return treeArray[index].toString();
   else
       findMinimumPricedHelper(name, treeArray, index+1);
   return null;
}

I was expecting a value treeArray[index].toString() but it returns null

Eran · Accepted Answer · 2019-05-19 10:41:03Z

4

You are ignoring the value of the recursive call. Try:

private String findMinimumPricedHelper(String name, IMedia[] treeArray, int index) {
    if (some conditions) {
        return treeArray[index].toString();
    } else {
        return findMinimumPricedHelper(name, treeArray, index+1);
    }
}

answered May 19, 2019 at 10:41

Eran

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Comments

Ali Ben Zarrouk · Accepted Answer · 2019-05-19 10:50:22Z

1

As @Eran said, you're missing the return of the recursive call, but you should also consider the case where the condition is never true and you reach the end of the array. This will crash if the condition is never met.

answered May 19, 2019 at 10:50

Ali Ben Zarrouk

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Comments

hqt · Accepted Answer · 2019-05-19 10:50:35Z

1

You forget return answer from recursion call.
I recommend you check corner case when index larger than size of array.
If you want to make sure this method never crashes, you should handle index less than zero, treeArray is null.

So ideal code should be:

private String findMinimumPricedHelper(String name, IMedia[] treeArray, int index) throws IllegalArgumentException {
   if (treeArray == null || index < 0) throw new IllegalArgumentException("parameters are not correct");
   if (index >= treeArray.length) return null;
   if(some conditions) return treeArray[index].toString();
   return findMinimumPricedHelper(name, treeArray, index+1);
}

answered May 19, 2019 at 10:50

hqt

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