Example of Android activity with image picker.

MainActivity.java

public class MainActivity extends AppCompatActivity {

  private final ActivityResultLauncher<String[]> galleryActivityLauncher
      = registerForActivityResult(new ActivityResultContracts.OpenDocument(),
     this::onPickImage);

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }

  // Assuming this is called on clicking a button or something.
  public void pickImage(View unused) {
    galleryActivityLauncher.launch(new String[]{"image/*"});
  }

  private void onPickImage(Uri imageUri) {
    // TODO: Load the selected image from URI.
  }
}