我无法让我的 recyclerview 保存方向更改的状态。在我的片段中使用了 onSaveInstanceState 但显然不正确，因为它不起作用。有关如何解决的任何建议和指示？
第二活动
public class SecondActivity extends AppCompatActivity {
private boolean mTwoPane;
ArrayList<Recipe> myList;
List<Steps> steps;
android.support.v7.app.ActionBar actionBar;
StepsFragment fragment;
//Eventbus
@Override
protected void onStart() {
super.onStart();
EventBus.getDefault().register(this);
}
@Override
protected void onStop() {
super.onStop();
EventBus.getDefault().unregister(this);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_two);
actionBar = getSupportActionBar();
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
myList = getIntent().getParcelableArrayListExtra("list");
String id = getIntent().getStringExtra("intent");
int result = Integer.parseInt(id);
steps = (ArrayList) myList.get(result - 1).getSteps();
String nameString = myList.get(result - 1).getName();
getSupportActionBar().setTitle(nameString);
if (findViewById(R.id.android_me_linear_layout) != null) {
mTwoPane = true;
if (savedInstanceState == null) {
Bundle arguments = new Bundle();
arguments.putParcelableArrayList("myList", myList);
arguments.putInt("result", result);
arguments.putBoolean("twoPane", mTwoPane);
StepsFragment fragment = new StepsFragment();
fragment.setArguments(arguments);
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, fragment)
.commit();
}
} else {
// We're in single-pane mode and displaying fragments on a phone in separate activities
mTwoPane = false;
Bundle arguments = new Bundle();
arguments.putParcelableArrayList("myList", myList);
arguments.putInt("result", result);
arguments.putBoolean("twoPane", mTwoPane);
StepsFragment fragment = new StepsFragment();
fragment.setArguments(arguments);
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, fragment)
.commit();
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onBackPressed() {
super.onBackPressed();
if(mTwoPane) {
startActivity(new Intent(SecondActivity.this, MainActivity.class));
finish();
}
}
@Subscribe(threadMode = ThreadMode.MAIN)
public void onMessage(Message event) {
if (event.getMessage() == 2) {
Fragment newFragment = new DetailFragment();
newFragment.setArguments(event.getBundle());
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.detail_container, newFragment);
transaction.addToBackStack(null);
transaction.commit();
Log.d(LOG_TAG, "Eventbus worked");
}
else if ( event.getMessage() == 3){
Fragment newFragment = new DetailFragment();
newFragment.setArguments(event.getBundle());
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
transaction.commit();
}
}
}
步骤片段
public class StepsFragment extends android.support.v4.app.Fragment {
ArrayList<Recipe> myList;
List<Steps> myStepsList;
List <Ingredients> ingredients;
private RecyclerView recyclerView;
StepItemRecyclerViewAdapter stepItemRecyclerViewAdapter;
private RecyclerView.LayoutManager mLayoutManager;
int result;
List<String> ingredientsString;
String string;
Boolean mTwoPane;
Parcelable listState;
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelableArrayList("myArrayListTwo",(ArrayList) myStepsList);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState == null || !savedInstanceState.containsKey("myArrayListTwo")){
myStepsList = new ArrayList<>();
}
else{
myStepsList = savedInstanceState.getParcelableArrayList("myArrayListTwo");
}
mTwoPane = getArguments().getBoolean("twoPane");
myList = getArguments().getParcelableArrayList("myList");
result = getArguments().getInt("result") - 1;
myStepsList = myList.get(result).getSteps();
ingredients = myList.get(result).getIngredients();
//Create a String array for all ingredients strings
ingredientsString = new ArrayList<>();
ingredientsString.add("Ingredients" + "\n");
for(int x = 0; x < ingredients.size(); x++){
ingredientsString.add(ingredients.get(x).getIngredient() + " " + ingredients.get(x).getQuantity() + " " + ingredients.get(x).getMeasure());
Log.d(LOG_TAG, ingredientsString.get(x).toString());
}
StringBuilder stringBuilder = new StringBuilder();
for(String s : ingredientsString){
stringBuilder.append(s + "\n");
}
string = stringBuilder.toString();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_steps, container, false);
recyclerView = (RecyclerView) rootView
.findViewById(R.id.my_recycler_view);
mLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(mLayoutManager);
stepItemRecyclerViewAdapter = new StepItemRecyclerViewAdapter(myStepsList);
recyclerView.setAdapter(stepItemRecyclerViewAdapter);
TextView textView = (TextView) rootView.findViewById(R.id.text_view);
textView.setText(string);
return rootView;
}
public class StepItemRecyclerViewAdapter
extends RecyclerView.Adapter<StepItemRecyclerViewAdapter.ViewHolder> {
private final List<Steps> mValues;
public StepItemRecyclerViewAdapter(List<Steps> items) {
mValues = items;
}
@Override
public StepItemRecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_list_content, parent, false);
return new StepItemRecyclerViewAdapter.ViewHolder(view);
}
@Override
public void onBindViewHolder(final StepItemRecyclerViewAdapter.ViewHolder holder, int position) {
holder.mItem = mValues.get(position);
holder.mContentView.setText(mValues.get(position).getShortDescription());
holder.mView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(mTwoPane){
Bundle args = new Bundle();
args.putParcelableArrayList("myList", myList);
args.putInt("result", result);
args.putString("int", holder.mItem.getId());
EventBus.getDefault().postSticky(new Message(2, args));
Log.d(LOG_TAG, "You clicked a button" + holder.mItem.toString());
} else if( mTwoPane == false){
Bundle args = new Bundle();
args.putParcelableArrayList("myList", myList);
args.putInt("result", result);
args.putString("int", holder.mItem.getId());
EventBus.getDefault().postSticky(new Message(3, args));
Log.d(LOG_TAG, "You clicked a button" + holder.mItem.toString());
}
}
});
}
@Override
public int getItemCount() {
return mValues.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public View mView;
public TextView mContentView;
public Steps mItem;
public ViewHolder(View view) {
super(view);
mView = view;
mContentView = (TextView) view.findViewById(R.id.content);
}
@Override
public String toString() {
return super.toString() + " '" + mContentView.getText() + "'";
}
}
}
}
activity_main_two.xml https://github.com/RJRogers/TwoPaneUITest/blob/master/app/src/main/res/layout/activity_main_two.xml
fragment_steps.xml https://github.com/RJRogers/TwoPaneUITest/blob/master/app/src/main/res/layout/fragment_steps.xml