Question

**JAVA**

Write a binary search method for a String array that might contain nulls. Your method should not crash or throw a runtime exception. See the driver program for examples. The method header is:

public static int binarySearchWithNulls(String[] words, String target) 

must be recursive.

Answer 1

// Note: for it to be recursive, we need to pass both left and right as parameters as well.
public static int binarySearchWithNulls(String[] words, String target, int left, int right) {
    if (left <= right) {
        int mid = (left + right) / 2;
        if (words[mid] == null) return -1;
        if (words[mid].equals(target)) {
            return mid;
        } else if (target.compareTo(words[mid]) < 0) {
            return binarySearchWithNulls(words, target, left, mid-1);
        } else {
            return binarySearchWithNulls(words, target, mid+1, right);
        }
    }
    return -1;
}

public static int binarySearchWithNulls(String[] words, String target) {
    if (words == null || target == null) return -1;
    return binarySearchWithNulls(words, target, 0, words.length-1);
}