Question

I have the following code, but it won’t compile:

Class<? extends something>[] classes = new Class<? extends something>[5]();

Why exactly won’t this work? And is there a way around this? I also tried it with Class<?> and that didn’t work either.

Answer 1

The answer has to do with Array Creation Expression.

The rule clearly states:

The rules above imply that the element type in an array creation
expression cannot be a parameterized type, other than an unbounded
wildcard.

That’s why your above code will never compile. In fact, the following compile-time error message shows (example):

/**
 * 
 */


/**
 * @author The Elite Gentleman
 *
 */
public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Class<? extends Exception>[] classes = new Class<? extends Exception>[5];
    }

}

Test.java:17: generic array creation

Solution (that works, if you follow the above rule):

Class<? >[] classes = new Class<?>[5];

The above line compiles.

I hope this helps.