src/main/java/org/organicdesign/fp/collections/RangeOfInt.java
@Override public int indexOf(Object o) {
        if (o instanceof Number) {
            int i = ((Number) o).intValue();
            if ( (i >= start) && (i < end) ) {
                return i - start;
            }
        }
        return -1;
    }
@Override public int indexOf(Object o) {
        if (o instanceof Number) {
            int i = ((Number) o).intValue();
            if ( (i >= start) && (i < end) ) {
                return i - start;
            }
        }
        return -1;
    }
@ Override public int indexOf ( Object o ) { if ( o instanceof Number ) { int i = ( ( Number ) o ) . intValue ( ) ; if ( ( i >= start ) && ( i < end ) ) { return i - start ; } } return - 1 ; }
Unlike most implementations of List, this method has excellent O(1) performance!
{@inheritDoc}
Unlike most implementations of List this method has excellent O ( 1 ) performance! {