CODEWITHSUNDEEP
javagenerics
Danny
Danny

Reputation: 343

Generic Method Not Compiling

I'v written a generic method to sort an object of Type T. My compiler is saying "cannot find symbol : method lte(T).

Any ideas what exactly my problem is?

interface Comparable<T>{
        boolean lte(T t);
}

class Sort<T extends Comparable<T>> {

    static <T> void sort(T[] s) {
        for (int i = 0; i<s.length; i++) {
            for (int j = i+1; j < s.length; j++) {
                if (s[i].lte(s[j])) {
                    T t;
                    t = s[i]; 
                    s[i] = s[j]; 
                    s[j] = t;
                }
            }
        }
    }

    public static void main(String[] args) {
        String[] names = {"Pete","Jill","May","Anne","Tim"};             
        sort(names);
        for (String s:names) 
            System.out.println(s);
    }
}

Upvotes: 0

Views: 74

Answers (1)

rgettman
rgettman

Reputation: 178263

You've made your sort method generic, with another <T> declaration, but it's not Comparable. Your sort method is static, so it can't use the class's <T>. In fact, the class's <T> isn't used. Try this:

// Not generic here anymore
class Sort {
   // Bound goes here
   static <T extends Comparable<T>> void sort(T[] s) {

Additionally, String doesn't extend your Comparable interface, so this won't work (String doesn't even have an lte method, anyway). You will need to pass in some objects that implement your Comparable.

At best, it's confusing to name your interface the same name as a built-in (and well-known) interface. I suggest renaming your Comparable interface to something like Lteable.

Upvotes: 1

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