为什么我的Activity扩展了ActionBarActivity？

Question

我下载了最新的SDK版本,当我创建一个新的Android项目时MainActivity,自动生成的扩展ActionBarActivity,但我想扩展Activity.

public class MainActivity extends ActionBarActivity {

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

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}

Answer 1

ActionBarActivity用于向后兼容.因此Android操作栏也适用于旧设备,请参阅文档.

使用支持库操作栏功能的活动的基类.

通过为活动扩展此类并将活动主题设置为Theme.AppCompat或类似主题,可以在API级别7或更高级别上运行时向活动添加ActionBar.

它是FragmentsActivity 的子类,FragmentsActivity 扩展了 Activity.==>所以不要担心你可以用普通活动做的所有事情,你也可以用ActionBarActivity做.

Answer 2

如果要扩展Activity类,可以在项目创建轨迹中选中"Empty Activity".

Answer 3

只需将ActionBarActivity替换 为Activity，然后转到代码顶部并替换import android.support.v7.app.ActionBarActivity; 以进口android.app.Activity;