我遇到了将片段事务添加到返回堆栈的问题。我有一个主Activity,在其中使用Menu Fragment填充布局:
public class MainActivity extends ActionBarActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getFragmentManager().beginTransaction().add(R.id.frag_container, new MainMenuFragment()).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);
}
接下来,在MainMenuFragment内,用户选择某个选项,导致菜单片段被替换为另一个片段:
public class MainMenuFragment extends Fragment implements OnItemClickListener{
GridView grid;
FragmentManager manager;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.main_menu_fragment, container, false);
manager = getActivity().getFragmentManager();
grid = (GridView) root.findViewById(R.id.gridView1);
grid.setAdapter(new MenuTileAdapter(getActivity()));
grid.setOnItemClickListener(this);
return root;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
FragmentTransaction trans = manager.beginTransaction();
if (position == 0){
trans.replace(R.id.frag_container, new BasicSettingsFragment());
trans.addToBackStack(null);
trans.commit();
}
}
据我的理解,这应该使得当用户在设备上按下返回按钮时,会回到菜单片段,但实际上却退出了应用程序。我做错了什么?