Java Tutorial - How to use Java generic interface

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In Java we create generic interface.

Syntax

Here is the generalized syntax for a generic interface:

interface interface-name<type-param-list> { // ...

type-param-list is a comma-separated list of type parameters. When a generic interface is implemented, you must specify the type arguments, as shown here:

class class-name<type-param-list> 
 implements interface-name<type-arg-list> {

Note

In general, if a class implements a generic interface, then that class must also be generic. If a class implements a specific type of generic interface, such as shown here:

class MyClass implements MinMax<Integer> { // OK

then the implementing class does not need to be generic.

Generic interfaces are specified like generic classes.

Example

interface MinMax<T extends Comparable<T>> {
 T max();//fromwww.java2s.com
}
class MyClass<T extends Comparable<T>> implements MinMax<T> {
 T[] vals;
 MyClass(T[] o) {
 vals = o;
 }
 public T max() {
 T v = vals[0];
 for (int i = 1; i < vals.length; i++) {
 if (vals[i].compareTo(v) > 0) {
 v = vals[i];
 }
 }
 return v;
 }
}
public class Main {
 public static void main(String args[]) {
 Integer inums[] = { 3, 6, 2, 8, 6 };
 Character chs[] = { 'b', 'r', 'p', 'w' };
 MyClass<Integer> a = new MyClass<Integer>(inums);
 MyClass<Character> b = new MyClass<Character>(chs);
 System.out.println(a.max());
 System.out.println(b.max());
 }
}

The code above generates the following result.

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