gistfile1.java

package com.urbanairship.util;

import android.util.SparseArray;

public class SparseStringArray extends SparseArray<String> {

    public SparseStringArray() {
        this(10);
    }

    public SparseStringArray(int initialCapacity) {
        super(initialCapacity);
    }

    @Override
    public int indexOfValue(String value) {
        int count = this.size();
        for (int i=0; i<count; i++) {
            String currentValue = this.valueAt(i);
            if ((currentValue == null && value == null) ||
                    (currentValue != null && currentValue.equals(value))) {
                return i;
            }
        }
        return -1;
    }
}

Here's a faster version using a reduced number of checks:

@Override
public int indexOfValue(final String value) {
    final int count = size();
    if (value != null) {
        for (int i = 0; i < count; i++)
            if (value.equals(valueAt(i)))
                return i;
    } else {
        for (int i = 0; i < count; i++)
            if (valueAt(i) == null)
                return i;
    }
    return -1;
}