@Override が通らないときの確認手順

名前・引数・可視性の3点が一致条件です。

 1  class Base {
 2      protected void run() {}
 3  }
 4  public class Main extends Base {
 5      @Override
 6      _______ void run() {}
           ^
 7      public static void main(String[] args) {
 8          new Main().run();
 9      }
10  }

Main.java:6: error: run() in Main cannot override run() in Base attempting to assign weaker access privileges; was protected

空欄を埋めてビルドを通す