how to remove selected images in grid view when long press happens in android

Question

I am new to android developer, after completing some example apps, I started to work grid view concepts. Here I'm trying to implement the following logics.

1.When long press happened upon images, selected images should be highlighted. 2.Need to know the selected images to delete the selected images.

I have completed to select the images from gallery, Now I need to long press images and delete the same using delete button.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/btn_browse"
        android:text="Browse"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/btn_delete"
        android:text="Delete"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <GridView
        android:id="@+id/grid_view"
        android:layout_width="match_parent"
        android:layout_height="660dp"
        android:columnWidth="90dp"
        android:gravity="center"
        android:horizontalSpacing="10dp"
        android:numColumns="3"
        android:stretchMode="columnWidth"
        android:verticalSpacing="10dp" />
</LinearLayout>

//Adapter class

class ImageAdapter extends BaseAdapter {
//Context c|ass is use to bind xm| with java

    private Context mcontext;

    ArrayList<Uri> ImageUriList = new ArrayList<Uri>();
    //Right c|ick and generate constructor
    //imp|ement methods then auto generate

    //Constructor ...Rigth c|ick and generate constructor
    public ImageAdapter(Context mcontext, ArrayList<Uri> image) {
        this.mcontext = mcontext;
        ImageUriList = image;
    }

    @Override
    public int getCount() {
        return (ImageUriList == null) ? 0 : ImageUriList.size();
    }

    @Override
    public Object getItem(int position) {
        return ImageUriList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {     
        ImageView imageView =new ImageView(mcontext);
        imageView.setImageURI(ImageUriList.get(position));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setLayoutParams(new GridView.LayoutParams(340,340));
        return imageView;
    }

}

// MainActivity

public class MainActivity extends AppCompatActivity {

    public static final int BROWSE_RESULT = 1;
    ImageAdapter imageAdapter;
    ArrayList<Uri> imagesUri = new ArrayList<Uri>();
    GridView gridView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Button btn_browse;
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridView= findViewById(R.id.grid_view);

        gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
              //  imagesUri.remove(i) ;
                gridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);
                //imageAdapter.notifyDataSetChanged();
                Toast.makeText(MainActivity.this, i + " Value ", Toast.LENGTH_SHORT).show();
                return false;
            }
        });

        btn_browse = findViewById(R.id.btn_browse);

        btn_browse.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                f_openImageExplorer(); 
            }
        });
    }

    public void f_openImageExplorer() {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(intent, BROWSE_RESULT);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode,Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == BROWSE_RESULT) {
            if (resultCode == MainActivity.RESULT_OK) {
                if (data.getClipData() != null) {
                    Toast.makeText(this,Integer.toString(resultCode) , Toast.LENGTH_SHORT).show();
                    int imageCount = data.getClipData().getItemCount();
                    for(int i = 0; i< imageCount;i++){
                        Uri imageUri = data.getClipData().getItemAt(i).getUri();
                        imagesUri.add(imageUri);                        
                        imageAdapter= new ImageAdapter(getBaseContext(), imagesUri);
                        gridView.setAdapter(imageAdapter);
                        imageAdapter.notifyDataSetChanged();
                    }
                }
                else
                {
                    Uri singleImageUri = data.getData();
                    imagesUri.add(singleImageUri);
                    ImageAdapter imageAdapter= new ImageAdapter(getBaseContext(), imagesUri);
                    gridView.setAdapter(imageAdapter);
                    imageAdapter.notifyDataSetChanged();
                }
            }
        }
    }
}

Answer 1

In your MainActivity you can track of all clicked images and save their positions in a separated ArrayList - and on your delete Button you can check the positions of clicked items and remove them from the main list - after that action is done , just update your ImageAdapter with the new list:

ArrayList<int> clickedImagesIdx = new ArrayList<int>();

 gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
    @Override
    public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
        gridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);
        ...
        clickedImagesIdx.add(i);
        return false;
    }
});

 deleteBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        if (clickedImagesIdx.size() > 0) {

            for (int i = 0; i < clickedImagesIdx.size(); i++) {
                imagesUri.remove(i);
            }

            clickedImagesIdx.clear();

            // here you will need to submit the new Uri list to your adapter 
            // and use notifyDataSetChange();
        }
    }
});