我正在尝试将数据从一个片段发送到另一个片段,我正在使用bundle。但是,每当我尝试从第二个片段中的该包中获取任何信息时,我会收到一条错误消息,说我正在尝试获取一个空对象。我在创建第二个片段之前已经设置了第二个片段的参数,并且在发送之前我还要向它添加信息。我无法找出问题所在。这是主片段中的接口代码,它应该打开详细信息片段
public interface ListClickHandler {
public void onlistElementClicked ( Bundle args); //we'll have to override it in the parent activity.
}//end interface.
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception
try {
mCallback = (ListClickHandler) activity;
}//end try
catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement ListClickHandler interface");
}//end catch
}
另外,我在两个地方创建捆绑包,一次在主片段中,其中包含一个列表,如果点击任何项目创建了捆绑包,则将信息添加到捆绑包中,并将该捆绑包传递给内部的方法接口如下,
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_todo_list, container, false);
mSimpleCursorAdapter=new SimpleCursorAdapter(getActivity(),R.layout.notes_row,null, from, to,0);
getLoaderManager().initLoader(LOADER_ID, null, this); //once this is done onCreateLoader will be called.
ListView listView = (ListView) rootView.findViewById(R.id.notes_list); //findViewById must be called using the rootView because we are inside a fragment.
listView.setAdapter(mSimpleCursorAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
Cursor cursor = mSimpleCursorAdapter.getCursor();
if (cursor != null && cursor.moveToPosition(position)) {
String category= cursor.getString(1);
String summary= cursor.getString(2);
String description=cursor.getString(3);
long id= cursor.getLong(cursor.getColumnIndex(NotesContract.NotesTable._ID));
int locationId= cursor.getInt(cursor.getColumnIndex(NotesContract.NotesTable.COLUMN_LOCATION));
String [] retrievedData= {category, summary, description};
if (getActivity().findViewById (R.id.fragment_container)!=null){
//two pane layout:
Bundle args = new Bundle();
args.putStringArray("data",retrievedData);
/*args.putInt("update", 1);*/
args.putLong("id", id);
args.putInt("locationId", locationId);
mCallback.onlistElementClicked(args );/*this is available in the parent activity*/
}
else {
// one pane layout:
Intent intent = new Intent(getActivity(), NotesDetails.class);
intent.putExtra(Intent.EXTRA_TEXT, retrievedData);
/*intent.putExtra("update", 1); */ //to indicate that the query should be update not insert.
intent.putExtra("id", id);
intent.putExtra("locationId", locationId); //whether it is 0 or 1
startActivity(intent);
}
}//end outer cursor if.
}
});
return rootView;
}
当我选择菜单中的某些项目如下所示时,我创建并调用该包的第二个位置是主活动(包含主片段),
@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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {//open the settings activity to enable the user to change the settings.
//open settings activity via intent here.
startActivity(new Intent (this, Settings.class));
return true;
}
if (id==R.id.text_note){ //open the details activity where the user can enter their notes and save it.
if (twoPane) {
args.putBoolean("location", false);
mCallBack.onlistElementClicked(args);
}
else {
Intent intent = new Intent(this, NotesDetails.class);
startActivity(intent);
return true; //this line is necessary
}
}//end if
if (id==R.id.location_note)
{
if (twoPane) {
args.putBoolean("location", true);
mCallBack.onlistElementClicked(args);
}
else {
//prepare intent here:
Intent intent = new Intent(this, NotesDetails.class);
intent.putExtra("location", true);
startActivity(intent);
}
}
return super.onOptionsItemSelected(item);
}
这是我在主要活动
中覆盖onlistElementClicked的方法@Override
public void onlistElementClicked(Bundle args) {
DetailsFragment detailsFragment = new DetailsFragment();
detailsFragment.setArguments(args);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_container, detailsFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
}//end interface method.
这就是我如何获取细节片段(应该从主片段打开的片段)的参数内的信息。
Bundle args=this.getArguments();
之后我使用args来获取包中的任何信息,但是我收到了之前提到的错误。
任何人都可以帮帮我吗?我在网上查了几个解决方案,对我来说没什么用。
谢谢。
答案 0 :(得分:0)
您应该像这样分配Bundle的值:
public void onCreate(Bundle savedInstance){
super.onCreate(savedInstance);
youtBandGlobalMember = getArguments();
}
答案 1 :(得分:0)
实际上,我没有在任何方法中调用它,它在片段类的主体中调用,并将其值赋给全局变量。这是错的吗?Bundle args=this.getArguments();
现在还为时过早。成员变量在构造对象时初始化,并且在您可以在片段对象上调用setArguments()
之前。
将getArguments()
调用推迟到片段中的on...()
生命周期回调之一。