Eclipse生成的主細節流在延伸ListFragment
的類中有一些回調魔術 - 我說魔術是因爲這就是當你是Android和Java noob時,看起來像是什麼:)在主細節流程中回調'魔術'
考慮下面的代碼有人可以回答我幾個問題:
- 什麼是
ListFragment
的onAttach
方法做mCallbacks = (Callbacks) activity
? - 哪
onItemSelected
方法調用onListItemClick
方法ListFragment
,需要執行的方法還是onItemSelected
在FragmentActivity
? - 所有這些
onItemSelected
方法需要id
類型String
(因爲DummyContent
id
是String
)。如果我將DummyContent
id
更改爲long
,那麼我需要更改哪些onItemSelected
方法?我試圖改變一個在FragmentActivity
但這@Override
所以我不能:(
謝謝
public class RecordingListFragment extends ListFragment {
private static final String STATE_ACTIVATED_POSITION = "activated_position";
private Callbacks mCallbacks = sDummyCallbacks;
private int mActivatedPosition = ListView.INVALID_POSITION;
public interface Callbacks {
public void onItemSelected(String id);
}
private static Callbacks sDummyCallbacks = new Callbacks() {
@Override
// NEEDS IMPLEMENTATION - i guess????
public void onItemSelected(String id) {
}
};
...
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
if (!(activity instanceof Callbacks)) {
throw new IllegalStateException("Activity must implement fragment's callbacks.");
}
mCallbacks = (Callbacks) activity;
}
@Override
public void onDetach() {
super.onDetach();
mCallbacks = sDummyCallbacks;
}
@Override
public void onListItemClick(ListView listView, View view, int position, long id) {
super.onListItemClick(listView, view, position, id);
mCallbacks.onItemSelected(DummyContent.ITEMS.get(position).id);
}
...
}
還有一檔...
public class RecordingListActivity extends FragmentActivity
implements RecordingListFragment.Callbacks {
private boolean mTwoPane;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recording_list);
getActionBar().setDisplayHomeAsUpEnabled(true);
if (findViewById(R.id.recording_detail_container) != null) {
mTwoPane = true;
((RecordingListFragment) getSupportFragmentManager()
.findFragmentById(R.id.recording_list))
.setActivateOnItemClick(true);
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onItemSelected(String id) {
if (mTwoPane) {
Bundle arguments = new Bundle();
arguments.putString(RecordingDetailFragment.ARG_ITEM_ID, id);
RecordingDetailFragment fragment = new RecordingDetailFragment();
fragment.setArguments(arguments);
getSupportFragmentManager().beginTransaction()
.replace(R.id.recording_detail_container, fragment)
.commit();
} else {
Intent detailIntent = new Intent(this, RecordingDetailActivity.class);
detailIntent.putExtra(RecordingDetailFragment.ARG_ITEM_ID, id);
startActivity(detailIntent);
}
}
}