cursorLoader in androidstudio-CodePudding

I'm a super beginner so I'm just following some project and I knew that startActivityforResult has been deprecated, so I changed the code by using ActivityResultLauncher. But I don't know how to fix CursorLoader error. Can you tell me how to fix it?

So the original code was this.

 protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        
        if(requestCode == PICK_PROFILE_FROM_ALBUM && resultCode == RESULT_OK) {

            String[] proj = {MediaStore.Images.Media.DATA};

            CursorLoader cursorLoader = new CursorLoader(this, data.getData(), proj, null, null, null);
            


            Cursor cursor = cursorLoader.loadInBackground();
            int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
            cursor.moveToFirst();

            //image path
            String photoPath = cursor.getString(column_index);

           
    }

This is the current code

ActivityResultLauncher<Intent> startActivityResult = registerForActivityResult(
            new ActivityResultContracts.StartActivityForResult(),
            new ActivityResultCallback<ActivityResult>() {
                @Override
                public void onActivityResult(ActivityResult result) {
                    
                    if(result.getResultCode() == Activity.RESULT_OK) {
                        Intent data = result.getData();
                        String[] proj = {MediaStore.Images.Media.DATA};

                        CursorLoader cursorLoader = new CursorLoader(this, data.getData(), proj, null, null, null);
                       

                        Cursor cursor = cursorLoader.loadInBackground();
                        int column_index =cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                        cursor.moveToFirst();

                        
                        String photoPath = cursor.getString(column_index);
 }

So the context in CursorLoader should be fixed. It needs 'Context' but it is ActivityResultCallback now.

CodePudding user response：

This is happening because the this keyword in this case is as it should, referring to the current context and the current context is the anonymous class,i.e. instance of ActivityResultCallback but the CursorLoader needs a reference to the instance of Context or Activity. The simple fix in this case is to append .this to the name of your class or activity

Say your Activity is MainActivity, so this

CursorLoader cursorLoader = new CursorLoader(this, data.getData(), proj, null, null, null);

will turn to this

CursorLoader cursorLoader = new CursorLoader(MainActivity.this, data.getData(), proj, null, null, null);

CodePudding user response：

Instead of writing this directly write youractivityname.this

Assuming your activity name to be MainActivity this is how you should be passing context:

CursorLoader cursorLoader = new CursorLoader(MainActivity.this, data.getData(), proj, null, null, null);

CodePudding user response：

It is typical situation in long running Projects that sometimes You will need to migrate Your existing code base to newer API.

About CursorLoader. If startActivityResult Launcher is field inside your Activity This line

CursorLoader cursorLoader = new CursorLoader(this, data.getData(), proj, null, null, null);

can be replaced with

CursorLoader cursorLoader = new CursorLoader(YourActivityClass.this, data.getData(), proj, null, null, null);

I also see that cursor is loaded on UI Thread and it can have an impact on performance