Java reflection/unsafe

ReflectionTest.java

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Field;
import sun.misc.Unsafe;

class S {
	private void privatePrintS () { System.out.println("This is in S."); };
	public void publicPrintS () { System.out.println("This is in S."); };
}

class A extends S {

	private static final Integer publicFinalInt = 100;
	public String publicString;
	public int publicInt;
	public int publicInt2;
	public int publicInt3;

	private A(String argString){
		this.publicString = argString;
	};

	private void privatePrintA () {};

	public A(int argInt){
		this.publicInt = argInt;
	};

	public A(){};

	public void publicPrintA () {};

	static void showPublicFinalInt(){
		System.out.println(publicFinalInt);
	}

}

//@SuppressWarnings("all")
class ReflectionTest {
	public static void main(String argv[]) throws Exception{
		Class classA = A.class;

		A instanceA = A.class.newInstance();

		instanceA = A.class
			.getConstructor(int.class)
			.newInstance(10);

		Class<?>[] params = { String.class };
		Constructor<A> constructor = A.class
			.getDeclaredConstructor(params);
		constructor.setAccessible(true);
		instanceA = constructor
			.newInstance(new String("instance of class A"));

		System.out.println( "[getMethods]" );
		for( Method method: instanceA.getClass().getMethods() ){
			System.out.print( method.getName() + ": " );
			for( Class<?> c : method.getParameterTypes() ){
				System.out.print( c.getName() + " " );
			}
			System.out.println( "" );
		}

		System.out.println( "[getDeclaredMethods]" );
		for( Method method: instanceA.getClass().getDeclaredMethods() ){
			System.out.println( method.getName() + ": " );
			for( Class<?> c : method.getParameterTypes() ){
				System.out.println( c.getName() + " " );
			}
			System.out.println( "" );
		}

		if(classA == instanceA.getClass()){
			System.out.println("classA and instanceA.getClass() are the same.");
		}else{
			System.out.println("classA and instanceA.getClass() are NOT the same.");
		}

		Field f = Unsafe.class.getDeclaredField("theUnsafe");
		f.setAccessible(true);
		Unsafe unsafe = (Unsafe) f.get(null);

		A.showPublicFinalInt();

		Field fld = A.class.getDeclaredField("publicFinalInt");
		f.setAccessible(true);

		// unboxing works
		unsafe.putObject(unsafe.staticFieldBase(fld),unsafe.staticFieldOffset(fld),200);
		A.showPublicFinalInt();

		unsafe.putObject(unsafe.staticFieldBase(fld),unsafe.staticFieldOffset(fld),new Integer(300));
		A.showPublicFinalInt();

		f = A.class.getDeclaredField("publicInt");
		System.out.println(unsafe.objectFieldOffset(f));

		f = A.class.getDeclaredField("publicString");
		System.out.println(unsafe.objectFieldOffset(f));

	}
}