gistfile1.java

public class Test {

	private Test() {
		System.out.println("private constructor has been called");
	}

	private void test() {
		System.out.println("private test() method has been called");
	}

}

public class Main {

	public static void main(String[] args) throws IllegalArgumentException,
			IllegalAccessException, InvocationTargetException,
			InstantiationException, SecurityException, NoSuchMethodException {

		Class<Test> clazz = Test.class;

		Constructor<Test> c = clazz.getDeclaredConstructor((Class[]) null);
		c.setAccessible(true); 
		Test test = c.newInstance((Object[]) null);

		Method privateMethod = clazz.getDeclaredMethod("test", (Class[]) null);
		privateMethod.setAccessible(true); 
		privateMethod.invoke(test, (Object[]) null);
	}

}