public boolean containsKey(Object key) {
        return indexOfKey(key) >= 0;
    }
Check whether a key exists in the array.

@param key The key to search for.
@return Returns true if the key exists, else false.
replugin-host-library/replugin-host-lib/src/main/java/com/qihoo360/replugin/utils/basic/SimpleArrayMap.java