package com.myapp; // change to your app's package name

import com.facebook.react.bridge.NativeModule;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;

import android.app.AlertDialog;

public class Jamon extends ReactContextBaseJavaModule {
  Jamon(ReactApplicationContext context) {
    super(context);
  }

  @Override
  public String getName() {
    return "Jamon";
  }

  @ReactMethod
  public void hello() {
    // Display a pop-up alert
    AlertDialog.Builder builder = new AlertDialog.Builder(getCurrentActivity());
    builder.setMessage("Hi, everybody!")
      .setTitle("Jamon")
      .setPositiveButton("OK", null);
    AlertDialog dialog = builder.create();
    dialog.show();
  }
}

// app/components/MyImageViewManager.java
package com.myapp; // change to your app's package name

import com.facebook.drawee.backends.pipeline.Fresco;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContext;
import com.facebook.react.uimanager.SimpleViewManager;
import com.facebook.react.uimanager.ThemedReactContext;
import com.facebook.react.views.image.ReactImageView;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.util.Log;
import android.view.View;

import java.net.URL;

public class MyImageViewManager extends SimpleViewManager<ReactImageView> {
  // This is the string we use to identify this view when we call
  // requireNativeComponent("MyImageView") in JS.
  public static final String REACT_CLASS = "MyImageView";

  // We hang onto a reference of our React app context for later use.
  ReactApplicationContext mCallerContext;
  ReactImageView mView;

  // This is the URL of the image we'll show
  private final String logoURL = "https://logos-world.net/wp-content/uploads/2021/10/Meta-facebook-Logo-700x394.png";

  // Constructor -- saves a reference to the React context
  public MyImageViewManager(ReactApplicationContext reactContext) {
    mCallerContext = reactContext;
  }

  // Required method to allow React Native to know what the name of this class is.
  @Override
  public String getName() {
    return REACT_CLASS;
  }

  // This method is where we create our native view.
  @Override
  protected ReactImageView createViewInstance(ThemedReactContext reactContext) {
    // Instantiate a new ReactImageView
    // Fresco is a Facebook library for managing Android images and the memory they use.
    // https://github.com/facebook/fresco
    mView = new ReactImageView(reactContext, Fresco.newDraweeControllerBuilder(), null, mCallerContext);

    // This "handler" allows the `startDownloading` thread to call back to *this* thread.
    // Otherwise crashy crashy!
    final Handler mainThread = new Handler();

    // We'll download the image now and apply it back to this view
    startDownloading(mainThread);

    // Return our view back to React Native.
    return mView;
  }

  // Download our image.
  private void startDownloading(final Handler mainThread) {
    // Create a new background thread to download our image
    new Thread(() -> {
      try {
        // Download, blocking THIS background thread but not the main one
        URL url = new URL(logoURL);
        final Bitmap bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());

        // Go back to the main thread and set the image bitmap
        mainThread.post(() -> mView.setImageBitmap(bmp));
      } catch (Exception e) {
        Log.e("ReactImageManager", "Error : " + e.getMessage());
      }
    }).start();
  }
}