android: how do i preserve the data in my arrayada

问题:

as above, is it done automatically? My list was empty once the orientation chMYanges? and nope, i need the orientation change =)

My adapter

public class ResultsAdapter extends ArrayAdapter<SearchItem> implements Filterable{

private ArrayList<SearchItem> subItems;
private ArrayList<SearchItem> allItems;// = new ArrayList<SearchItem>();
private LayoutInflater inflater;
private PTypeFilter filter;
private OnCheckedChangeListener test;

public ResultsAdapter(Context context, int textViewResourceId, ArrayList<SearchItem> items,OnCheckedChangeListener a) {

    super(context, textViewResourceId, items);
        //this.subItems = items;
        for( int i = 0;i < items.size();i++){
            subItems.add(items.get(i));
        }
        this.allItems = this.subItems;
        inflater= LayoutInflater.from(context);

        test = a;
}

My onCreate

    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);        



    ListView lvr = (ListView)findViewById(R.id.search_results);



  //  if(savedInstanceState == null){
        this.m_adapter = new ResultsAdapter(home.this, R.layout.listrow, sResultsArr,home.this);
        this.specsAdapter = new FeaturesExpandableAdapter(home.this,new ArrayList<String>(),new ArrayList<ArrayList<Feature>>()); 
   // }
        lvr.setAdapter(this.m_adapter);

thanks guys

回答1:

You can also use http://developer.android.com/reference/android/app/Activity.html#onRetainNonConfigurationInstance()

Something like this in your Activity:

@Override
public Object onRetainNonConfigurationInstance() {
    return this.m_adapter.getItems();
}

And then in your onCreate():

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);

    // more init stuff here

    sResultsArr = (ArrayList<SearchItems>)getLastNonConfigurationInstance();
    if(sResultArr == null) {
        sResultsArray = new ArrayList<SearchItems>();  // or some other initialization
    }

    self.m_adapter = new ResultsAdapter(home.this, R.layout.listrow, sResultsArr,home.this);

    // ...
}

回答2:

If you have data in memory that needs to stick around during an orientation change, you need to do something to arrange that. The best solution is to implement onSaveInstanceState() and use it to store your data, because that gets used not only for orientation changes, but other situations as well (e.g., your activity is on the current stack, but it needs to get kicked out of RAM to free up space for things later in the stack).

回答3:

I think you're on the wrong way. Please take some time to see this video from Android's developers: http://www.youtube.com/watch?v=wDBM6wVEO70 (about 1 hour).

I followed the video, and my list view works fine when screen changes orientation :-)

回答4:

I solved this problem using OnSaveInstanceState() and OnRestoreInstanceState()

@Override
    protected void onRestoreInstanceState(Bundle state){
        super.onRestoreInstanceState(state);
        name_array.addAll(state.getStringArrayList("key"));
        setListAdapter(arrayAdapter);
        arrayAdapter.notifyDataSetChanged();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState){
        super.onSaveInstanceState(outState);
        outState.putStringArrayList("key",name_array);
    }

name_array is hold in ArrayAdapter arrayAdapter = new ArrayAdapter<String>(this ,R.layout.item,name_array);

Now when you change from landscape to portrait and reverse, data aren't los

回答5:

The data should not be lost when you change the orientation. The only thing I can imagine is that the layout for your activity is not correct, like, controls move out of the visible area upon changing the orientation.

回答6:

Please put this code in your AndroidManifest.xml file.

activity
        android:name="MainActivity"
        android:label="@string/app_name" 
        android:configChanges="keyboardHidden|orientation|screenSize"