如何获取 itemList.size() 或 itemList 从适配器到 MainActivity

Question

从代码片段中，我记录了一些调试点，发现mImages.size()在不同的地方给出了不同的输出。 无论mImages.seize()的值如何，它总是以public ArrayList<Uri> getImageUris()返回0... ...有什么帮助吗？

public class ImagesAdapter extends RecyclerView.Adapter<ImagesAdapter.ImageViewHolder> {
private ArrayList<Image> mImages;
private ArrayList<Uri> mImagesUri = new ArrayList<>();
private Image mimage;
private Uri uris;
private static final String TAG = "ImagesAdapter";
public ImagesAdapter(ArrayList<Image> images) {
mImages = images;
if (mImages == null)
Log.d(TAG, "ImagesAdapter mImages = null");
}
@Override
public ImageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new ImageViewHolder(LayoutInflater.from(parent.getContext())
.inflate(R.layout.list_pic_update, parent, false));
}
@Override
public void onBindViewHolder(ImageViewHolder holder, final int position) {
holder.bind(mImages.get(position));
holder.cancel.setOnClickListener(view -> {
int rpos = holder.getAdatpterpos();
removeAt(rpos, mImages.get(position).getSource());
Log.d(TAG, "imagesAdapter position = " + position);
});
}
@Override
public int getItemCount() {
Log.d(TAG, "imagesAdapter getItemCount = " + mImages.size());
return mImages.size();

}

public class ImageViewHolder extends RecyclerView.ViewHolder {
protected ImageView imageView;
private ImageButton cancel;
public ImageViewHolder(View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.news_pic_update_details);
cancel = itemView.findViewById(R.id.cancel_image);
}
public void bind(Image image) {
imageView.setImageBitmap(image.getImage());
imageView.setImageURI(image.getSource());
Log.d(TAG, "imagesAdapter bind successful");
}
public int getAdatpterpos() {
return getAdapterPosition();
}
}

public void removeAt(int position, Uri path) {
String mPath = null;
File filepath;
File mfilepath = null;
try {
mPath = path.toString();
filepath = new File(mPath);
mfilepath = new File(filepath.getAbsolutePath());
mfilepath.delete();
} catch (Exception e) {
Log.e(TAG, "No Delete !!" + mPath + mfilepath);
e.printStackTrace();
}
mImages.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, mImages.size());
Log.d(TAG, "remove size = " + mImages.size());
notifyDataSetChanged();
}
public ArrayList<Uri> getImageUris() {// here mImages.size is always 0
if (!mImages.isEmpty()) {
Log.d(TAG, "getImagesUris != Null n mImages.size() = " + mImages.size());
for (Image imageuri : mImages) {
uris = imageuri.getSource();
mImagesUri.add(uris);
}
Log.d(TAG, "getImagesUris != Null" + mImagesUri);
return mImagesUri;

} else
Log.d(TAG, "getImagesUris = Null n mImages.size() = " + mImages.size());
return null;
}
}

片段

private ArrayList<Image> mImages = new ArrayList<>();
private ImagesAdapter mImagesAdapter = new ImagesAdapter(mImages);
private static final String TAG = "UploadNewsFragment";
private Object[] mdata = new Object[2];
/**
<...>
*/
private class loadImageTask extends AsyncTask<Object, Void, Bitmap> {
Bitmap image = null;
Uri uri, uriSource;
@Override
protected void onPreExecute() {
super.onPreExecute();
}
protected Bitmap doInBackground(Object... obj) {
uri = (Uri) obj[1];
uriSource = (Uri) obj[0];
try {
// Use the MediaStore to load the image.
image = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), uri);
} catch (IOException e) {
e.printStackTrace();
Log.e(TAG, "Error: " + e.getMessage() + "Could not open URI: "
+ uri.toString());
}
return null;
}

protected void onPostExecute(Bitmap resultimage) {
mImages.add(new Image(uriSource, image)); //here adds to the list
mImagesAdapter.notifyDataSetChanged();
mRecyclerView.smoothScrollToPosition(mImagesAdapter.getItemCount() - 1);
Log.d(TAG, "OnPostExecute mImages.size() =" + mImages.size());// the mImages.s1ze() returns the correct value
}}

主活动

private ArrayList<Uri> newsImagesuri = new ArrayList<>();
private ArrayList<String> uris = new ArrayList<>();
String uriTostring;
CW update;
private ArrayList<Image> newsImages = new ArrayList<>();
private ImagesAdapter mImagesAdapter = new ImagesAdapter(newsImages);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mCompressor = new FileCompressor(this);

Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = findViewById(R.id.fab);
// Called here..
fab.setOnClickListener(view -> 
upload_crime(view)
);
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
navigationView.setNavigationItemSelectedListener(this);
//add this line to display menu1 when the activity is loaded
displaySelectedScreen(R.id.nav_home);

cwViewModel = ViewModelProviders.of(this)
.get(CWViewModel.class);

}
/**
<...>
*/
public void upload_crime(View view) {
EditText update_news = findViewById(R.id.update_news);
String contents = update_news.getText().toString();
Date now = Calendar.getInstance().getTime();
newsImagesuri = mImagesAdapter.getImageUris(); // Here returns null from adapter
if (newsImagesuri != null) {
Log.d(TAG, "newsImagesuri != null" + newsImagesuri);
for (Uri uri : newsImagesuri) {
uriTostring = uri.toString();
uris.add(uriTostring);
Log.d(TAG, "converted uris" + uris);
}
update = new CW(now, contents, uris);
Log.d(TAG, "update contain uri" + uris);
} else {
Log.d(TAG, "newsImagesuri = null");
update = new CW(now, contents, null);
}

堆栈跟踪

D/ImagesAdapter: imagesAdapter getItemCount = 0
imagesAdapter getItemCount = 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 1
D/ImagesAdapter: getImagesUris = Null 
mImages.size() = 0
D/MainActivity: newsImagesuri = null
D/TextView: setTypeface with style : 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 1
D/ViewRootImpl: ViewPostImeInputStage processPointer 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 1
show : false
I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@27bdf29 time:17894100
D/ImagesAdapter: imagesAdapter getItemCount = 1
D/UploadNewsFragment: OnPostExecute mImages.size() =1
D/ImagesAdapter: imagesAdapter getItemCount = 1
imagesAdapter getItemCount = 1
imagesAdapter getItemCount = 1
I/BitmapFactory: DecodeImagePath(decodeResourceStream3) : value is null. res : null
D/ImagesAdapter: imagesAdapter bind successful
imagesAdapter getItemCount = 1
imagesAdapter getItemCount = 1
imagesAdapter getItemCount = 1
D/ViewRootImpl: ViewPostImeInputStage processPointer 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 1
D/ImagesAdapter: getImagesUris = Null 
mImages.size() = 0
D/MainActivity: newsImagesuri = null
D/TextView: setTypeface with style : 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 0
D/ViewRootImpl: ViewPostImeInputStage processPointer 1
V/ActivityThread: updateVisibility : ActivityRecord{8f2490 token=android.os.BinderProxy@27bdf29 {com.x.unncrimewatch/com.x.unncrimewatch.MainActivity}} show : true
V/ActivityThread: updateVisibility : ActivityRecord{8f2490 token=android.os.BinderProxy@27bdf29 {com.x.unncrimewatch/com.x.unncrimewatch.MainActivity}} show : false

Answer 1

我想我知道为什么。您在MainActivity和Fragment有 2 个不同的映像列表，有 2 个单独的适配器。

您已将项目添加到片段中的列表中，但主活动中的列表永远不会更新。

因此，当您在 MainActivity 中调用upload_crime()时，图像列表的大小始终为 0。

您应该只在一个地方与适配器交互，最好是片段

Answer 2

当您想将信息从Array传递到其他Array时，您做错了什么。你不能这样做 ->mImages = images;.

你可能会问为什么?...当你这样做时，mImages均衡到images，换句话说，如果你清除图像(images.clear(。mImages也将被清除。

你需要做的 是mImages.addAll(images);通过这种方式，两者都将具有相同的data但两者都会不同，换句话说，如果你清除其中一个数组......另一个不会被清除。

一定要在你做这个array = array的每个地方实施我告诉你的。

希望它