Question

我正在处理一个显示图像列表的片段。它具有用于“添加图像”的按钮，用于使用这些值启动结果的意图。

type: "image/*"
action: Intent.ACTION_GET_CONTENT

问题是：用户选择图像并返回到片段后，列表中的所有其他图像（存储在代码中的ArrayList <>中）都消失了。

我已覆盖方法onSaveInstanceState(Bundle)并将列表保存在捆绑软件中。问题是，无法将其还原。

我想到了覆盖onViewStateRestored(Bundle)，但是没有用。当我在所有“ onXXX”方法上放置Log.d()时，我发现每次添加文件（实际顺序）时仅执行这三个：

onPause()
onSaveInstanceState(Bundle)
//now the image picker opens up
//user picks the image
onResume()
//image picker closes and fragment is now on screen

我曾想过在onResume()使用某种“ getXXX”方法，但是找不到有用的方法。我该怎么办？

编辑：这是我的代码（没有无关紧要的内容）。

@Override public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    Log.d("debugaff", "oncreate");
    setRetainInstance(true);
    this.attachments = (ArrayList<Attachment>) getActivity().getIntent().getSerializableExtra(ExtraKeys.ATTACHMENTS);
}

@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
    Log.d("debugaff", "oncreateview");
    rootView = inflater.inflate(R.layout.fragment_attachments_form, container, false);

    //....

    if(savedInstanceState == null){
        getLoaderManager().initLoader(0, null, this);
    } else {
        attachmentsRvAdapter.setItems((List<Attachment>) savedInstanceState.getSerializable(ExtraKeys.TEMP_ATTACHMENTS));
    }

    //....

    return rootView;
}

@Override public void onResume(){
    super.onResume();
    Log.d("debugaff", "onresume");
    hideKeyboard();
}

@Override public void onPause(){
    super.onPause();
    setRetainInstance(true); //called this to make it 100% redundant (already called it at onCreate)
    Log.d("debugaff", "onpause");
}

@Override public void onViewStateRestored(@Nullable Bundle savedInstanceState){
    Log.d("debugaff", "onviewstaterestored");
    if(savedInstanceState == null){
        getLoaderManager().initLoader(0, null, this);
    } else {
        attachments.addAll((List<Attachment>) savedInstanceState.getSerializable(ExtraKeys.TEMP_ATTACHMENTS));
        attachmentsRvAdapter.setItems(attachments);
    }

    super.onViewStateRestored(savedInstanceState);
}

Answer 1

我只是模仿您的情况，没有发现错误（列表将新值与旧值保存在列表中）。我能想到的唯一问题是您没有正确初始化列表。我所做的是在onCreate（）方法中初始化了列表，当我选择另一个Image时，它将该图像保存在同一列表中，而先前的图像仍在列表中。 无需将列表单独保存在savedInstanceBundle中。这是我的片段代码：

public class SelectListFragment extends Fragment {


private static final int PICK_IMAGE_REQUEST = 11;

public SelectListFragment() {
    // Required empty public constructor
}

List listOfImagesSelected;
Button selectButton;

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    listOfImagesSelected=new ArrayList<Bitmap>();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_select_list, container, false);

    selectButton = view.findViewById(R.id.selectButton);
    selectButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent();
            intent.setType("image/*");
            intent.setAction(Intent.ACTION_GET_CONTENT);
            startActivityForResult(Intent.createChooser(intent, "Select Picture"), PICK_IMAGE_REQUEST);
        }
    });
    return view;
}


@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);


    //I am retrieving the Bitmap from the intent and saving into the list 
    if (requestCode == PICK_IMAGE_REQUEST && resultCode == Activity.RESULT_OK && data != null && data.getData() != null) {
        Uri uri = data.getData();

        try {
            //making the bitmap from the link of the file selected
            Bitmap bitmap = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), uri);
            listOfImagesSelected.add(bitmap);
        }catch (Exception e){

        }

    }
}
}

如果需要，我可以共享我的项目的完整工作代码。为了更好地了解Fragment LifeCycle，请查看此图片

Answer 2

要使用onViewStateRestored，您需要调用“ setRetainInstance（true）;”

在ActivityResult之后还原片段状态

2 个答案: