Question

每当我按下我的应用程序的后退按钮时，都会发生以下情况。

原手机显示：FragA

点击FragA上的视图后手机显示：FragB

点击后退按钮后手机显示：弗拉加弗拉加

我不知道为什么会重新创建FragA，但是当按下后退按钮时会将其添加到上一个FragA的末尾。以下是我的代码。

public class ColorListFragment extends ListFragment {
private List<ColorGD> mDrawableList = null;
private ColorAdapter mAdapter = null;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_color_list, container, false);
}

@Override
public void onActivityCreated(Bundle savedInstanceState){

    super.onActivityCreated(savedInstanceState);
        populateList();
        getListView().setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            ColorGD viewItem = mDrawableList.get(position);
            float[] hues = {viewItem.getColor(0),viewItem.getColor(1)};

            Bundle args = new Bundle();
            final String hueValues = "hues";
            args.putFloatArray(hueValues,hues);

            SaturationListFragment sLF = new SaturationListFragment();
            sLF.setArguments(args);

            FragmentManager manager = getFragmentManager();
            FragmentTransaction transaction = manager.beginTransaction();
            transaction.replace(R.id.container,sLF);
            transaction.addToBackStack(null);
            transaction.commit();
        }
    });
}

我的主要活动有以下

public class MainActivity extends Activity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    addListFragment();
 }

  public void addListFragment(){
    ColorListFragment cLF = new ColorListFragment();
    FragmentManager manager = getFragmentManager();
    FragmentTransaction transaction = manager.beginTransaction();
    transaction.add(R.id.container,cLF);
    transaction.commit();
  }
}

Answer 1

我想我知道这里发生了什么。 Fragment实际上不可能只与一个视图容器重复。

我怀疑由于ListFragment中对populateList()的调用，onActivityCreated()中的项目会重复。

因为每次点击后退按钮从onActivityCreated()返回ColorListFragment时都会调用SaturationListFragment，所以每次都会调用populateList()。见documentation here

要解决您的问题，只需将通话移至populateList()至onCreate()，这仅在ListFragment首次初始化时调用：

public class ColorListFragment extends ListFragment {
  private List<ColorGD> mDrawableList = null;
  private ColorAdapter mAdapter = null;

  //add the onCreate() override
  @Override
  public void onCreate(Bundle savedInstance){
      super.onCreate(savedInstance);
      populateList();  //add this here
  }

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
      return inflater.inflate(R.layout.fragment_color_list, container, false);
  }

  @Override
  public void onActivityCreated(Bundle savedInstanceState){
      super.onActivityCreated(savedInstanceState);
      //populateList();  //remove this
      //..................

按下后退按钮时，addToBackStack（）复制原始片段

1 个答案: