在父级 Activity 中实现内部片段 class

Question

我有以下代码：

public class SettingsActivity extends AppCompatActivity implements SettingsActivity.SettingsFragment.SendToActivity {
  ...
  public static class SettingsFragment extends PreferenceFragmentCompat {
    
    SendToActivity callback;

    public void setSendToActivity (SendToActivity callback) {
      this.callback = callback;
    }

    public interface SendToActivity {
      public void send(int result);
    }
    ...
  }

  @Override
  public void onAttachFragment(Fragment fragment) {
    if (fragment instanceof SettingsFragment) {
      SettingsFragment settingsFragment = (SettingsFragment) fragment;
      settingsFragment.setSendToActivity(this);
    }
  }

  public void send(int result) {
    ...
  }
}

但我收到以下错误：cyclic inheritance involving SettingsActivity 在 SettingsActivity class 的声明中。我做错了什么？

Answer 1

尝试将 SendToActivity 移出 SettingsFragment，例如：

public class SettingsActivity extends AppCompatActivity implements SettingsActivity.SendToActivity {
  public interface SendToActivity {
    public void send(int result);
  }

  ...

  public static class SettingsFragment extends PreferenceFragmentCompat {
    
    SendToActivity callback;

    public void setSendToActivity (SendToActivity callback) {
      this.callback = callback;
    }

    ...

  }

  @Override
  public void onAttachFragment(Fragment fragment) {
    if (fragment instanceof SettingsFragment) {
      SettingsFragment settingsFragment = (SettingsFragment) fragment;
      settingsFragment.setSendToActivity(this);
    }
  }

  public void send(int result) {
    ...
  }
}

Answer 2

我自己回答：片段 class 需要在其自己的 java 文件中。那就正常实现吧(implements SettingsFragment.SendToActivity).

在父级 Activity 中实现内部片段 class

Implements inner Fragment class in parent Activity

android

fragment

android-activity