更新#2
感谢AgentP暗示我的问题。 通过在showImages（）中进行更改，我已修复了此问题:
（还创建了全局引用字段字符串路径；在相同的activity中）:
private void showImages(){
// Added following two lines :
ContextWrapper cw = new ContextWrapper(this); // + added
path = cw.getDir("files", Context.MODE_PRIVATE).toString(); // + added
// String path = DrawingActivity.path; // - removed
allFilesPaths = new ArrayList<>();
allFilesPaths = listAllFiles(path);
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.galleryRecycleViewId);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getApplicationContext(), 3);
recyclerView.setLayoutManager(layoutManager);
ArrayList<Cell> cells = prepareData();
ImageAdapter adapter = new ImageAdapter(getApplicationContext(), cells);
recyclerView.setAdapter(adapter);
}
更新
显然，我有一个静态字符串，只设置在保存图像方法。 它的目的是为show images方法提供图像文件夹路径。 我现在正试图通过其他方法为showImages（）方法提供路径。
旧的
我有一个画廊activity，显示图像从一个文件夹与回收器视图。
当我启动我的应用程序时，图片库是空的，尽管文件夹中有图片。
当我去我的绘图activity，保存一个图像，并返回画廊activity它显示所有的图像没有问题。
我在onbindviewholder方法中放置了一个日志，它只在我保存图像后执行。
图像适配器缺少什么功能来查看退出的文件，图像保存做什么来使它在执行时找到它们？
（我还记得当我编写save image方法时，它希望我做@SuppressLint（“错误线程”），但现在它没有它也能工作）
在绘图activity中未保存文件而打开库时调试信息:
在画廊activity内显示图像所涉及的方法:
List <Cell> allFilesPaths;
// on create calls show images after checking if read storage permission is good
private void showImages(){
// this is the current problem line ,
// I need a way to give path of my image folder to this method
// Check SaveImage() method below to see how it is initially set
// path is a global static field inside drawing activity
String path = DrawingActivity.path;
allFilesPaths = new ArrayList<>();
allFilesPaths = listAllFiles(path);
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.galleryRecycleViewId);
recyclerView.setHasFixedSize(true);
RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getApplicationContext(), 3);
recyclerView.setLayoutManager(layoutManager);
ArrayList<Cell> cells = prepareData();
ImageAdapter adapter = new ImageAdapter(getApplicationContext(), cells);
recyclerView.setAdapter(adapter);
}
private ArrayList<Cell> prepareData(){
ArrayList<Cell> allImages = new ArrayList<>();
for (Cell c : allFilesPaths){
Cell cell = new Cell();
cell.setTitle(c.getTitle());
cell.setPath(c.getPath());
allImages.add(cell);
}
return allImages;
}
private List<Cell> listAllFiles(String pathName){
List<Cell> allFiles = new ArrayList<>();
if(pathName != null){
File file = new File(pathName);
File[] files = file.listFiles();
if(files != null){
for (File f : files){
Cell cell = new Cell();
cell.setTitle(f.getName());
cell.setPath(f.getAbsolutePath());
allFiles.add(cell);
}
}
}
return allFiles;
}
在我的映像适配器中:
private ArrayList<Cell> galleryList;
private Context context;
private static final String TAG = "ImageAdapter";
public ImageAdapter(Context context, ArrayList<Cell> galleryList) {
this.context = context;
this.galleryList = galleryList;
}
@NonNull
@Override
public ImageAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cell, parent, false);
return new ImageAdapter.ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull ImageAdapter.ViewHolder holder, final int position) {
holder.img.setScaleType(ImageView.ScaleType.CENTER_CROP);
Log.d(TAG, "onBindViewHolder: " + galleryList.size());
setImageFromPath(galleryList.get(position).getPath(), holder.img);
holder.img.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String path = galleryList.get(position).getPath();
Intent intent = new Intent(context ,ImagePreview.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.putExtra("imagePath",path);
context.startActivity(intent);
}
});
}
@Override
public int getItemCount() {
return galleryList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
private ImageView img;
public ViewHolder(@NonNull View itemView) {
super(itemView);
img = (ImageView) itemView.findViewById(R.id.img);
}
}
private void setImageFromPath(String path, ImageView image){
File imgFile = new File(path);
try {
Bitmap myBitmap = BitmapFactory.decodeStream(new FileInputStream(imgFile));
image.setImageBitmap(myBitmap);
// ImageView imageView = (ImageView)findViewById(R.id.imageViewSelect);
// imageView.setImageBitmap(bitmap);
}catch (FileNotFoundException e){
e.printStackTrace();
}
}
在绘制activity内保存图像的方法:
public void saveImage() {
ContextWrapper cw = new ContextWrapper(getContext());
String filename = "img" + System.currentTimeMillis();
File directory = cw.getDir("files", Context.MODE_PRIVATE);
path = cw.getDir("files", Context.MODE_PRIVATE).toString();
File myPath = new File(directory, filename + ".jpg");
FileOutputStream fileOutputStream = null;
try {
fileOutputStream = new FileOutputStream(myPath);
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
}catch(Exception e){
e.printStackTrace();
}finally {
try {
fileOutputStream.flush();
fileOutputStream.close();
}catch (IOException e){
e.printStackTrace();
}
}
}
确保showImages()中的变量DrawingActivity.Path包含一些值。 它可能没有正确初始化。
尝试将其放入ViewHolder类构造函数中
setImageFromPath(galleryList.get(getLayoutPosition()).getPath(), holder.img);
