BasicUnit.java

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/*
 * @test
 * @bug 5030212
 * @summary please add a typesafe cast for Class<?> types
 * @author gafter
 *
 * @compile -Xlint:unchecked -Werror BasicUnit.java
 * @run main BasicUnit
 */

interface Int {
    void main();
}

class MyInt implements Int {
    public void main() {
        System.out.println("Hello, world!");
    }
}

public class BasicUnit {
    static <T extends Int> T factory(Class<T> c) throws Throwable {
        return c.newInstance();
    }
    public static void main(String[] args) throws Throwable {
        factory(Class.forName("MyInt").asSubclass(Int.class)).main();
    }
}