Java Community | Help. Code. Learn.•2y ago

Object sequential searching using compareTo()

I have this simple method to search for an object that uses Comparable interface. But I'm wondering, why does my parameter should use extends instead of implements? Doesn't this break the law where an object can only extend ONE class, but is able to implement multiple interfaces? So why doesn't implements work here?

    public static <T extends Comparable<T>> int sequentialSearch(T[] list, T key) {
        for (int i = 0; i < list.length; i++) {
            if (list[i].compareTo(key) == 0)
                return i;
        }
        return -1;
    }

    public static <T extends Comparable<T>> int sequentialSearch(T[] list, T key) {
        for (int i = 0; i < list.length; i++) {
            if (list[i].compareTo(key) == 0)
                return i;
        }
        return -1;
    }

12 Replies

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circleOP•2y ago

why isn't it: <T Comparable<T>> Another method I can use is using raw implementation of casting the to be compared object to Comparable interface. But this still means it was casted to a class(?) instead of the interface.

    public static int sequentialSearch(Object[] x, Object key) {
        for (int i = 0; i < x.length; i++) {
            if ( ((Comparable) x[i]).compareTo(key) == 0 )
                return i;
        }
        return -1;
    }

    public static int sequentialSearch(Object[] x, Object key) {
        for (int i = 0; i < x.length; i++) {
            if ( ((Comparable) x[i]).compareTo(key) == 0 )
                return i;
        }
        return -1;
    }

Unknown User•2y ago

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circleOP•2y ago

Sorry for the late reply, does that mean T as the parameter data type is already an interface? TIA

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circleOP•2y ago

So T can be extended into any interface? Even though interface is not a class?

Unknown User•2y ago

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Carter•2y ago

T extends InterfaceB & InterfaceC is valid syntax

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JavaBot•2y ago

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Object sequential searching using compareTo()