amaembo / quiz

quiz

quiz

Short quiz:

1. Look into new JEP274 API.
2. Explain what the following code does?

public static MyClass {

 public static boolean less(int i, int cnt) {
    return i<=cnt;
}

public static void main(String[] args) throws Throwable {


    MethodHandle mhLoop = MethodHandles.loop(
            new MethodHandle[]{
                    MethodHandles.dropArguments(MethodHandles.constant(int.class, 1), 0, int.class),
                    MethodHandles.insertArguments(
                            MethodHandles.lookup().findStatic(Integer.class, "sum", MethodType.methodType(int.class, int.class, int.class)), 1 , 1),
                    MethodHandles.dropArguments(
                            MethodHandles.lookup().findStatic(MethodHandlesLoop.class, "less", MethodType.methodType(boolean.class, int.class, int.class)), 1, int.class, int.class, int.class),
                    MethodHandles.dropArguments(MethodHandles.dropArguments(
                            MethodHandles.identity(int.class), 0, int.class, int.class), 3, int.class, int.class)
            },
            new MethodHandle[]{
                    null,
                    MethodHandles.dropArguments(
                            MethodHandles.lookup().findStatic(Integer.class, "sum", MethodType.methodType(int.class, int.class, int.class)), 0, int.class, int.class),
                    null,
                    null
            },
            new MethodHandle[]{
                    MethodHandles.constant(int.class, 1),
                    MethodHandles.dropArguments(MethodHandles.identity(int.class), 0, int.class, int.class, int.class),
                    null,
                    null
            },
            new MethodHandle[]{
                    MethodHandles.constant(int.class, 1),
                    MethodHandles.dropArguments(MethodHandles.identity(int.class), 0, int.class),
                    null,
                    null
            });

    System.out.println((int)mhLoop.invokeExact(8));
}

}