我正在尝试根据指南制作一个简单的Android应用程序。我正在使用下面的代码，但它给了我几个错误。尝试覆盖该onCreate()方法时抱怨。确切的错误如下。谁能解释我在这里犯什么错误？

package com.bignerdranch.android.geoquiz;

import android.os.Bundle;

public class CheatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cheat);
    }

}

确切的错误：

The method onCreate(Bundle) is undefined for the type Object
The method setContentView(int) is undefined for the type CheatActivity
The method onCreate(Bundle) of type CheatActivity must override or implement 
a supertype method