'Flutter:MainActivity cannot be converted to FlutterEngine in Java Native code

I am trying to create a plugin for Flutter in Java. I am trying to pass the Android activity parameter in my main Java class.

This is my native code: 

package com.example.trsurveys;

import androidx.annotation.NonNull;
import android.app.Activity;

import io.flutter.embedding.engine.plugins.FlutterPlugin;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
import io.flutter.plugin.common.MethodChannel.Result;
import io.flutter.plugin.common.PluginRegistry.Registrar;

import theoremreach.com.theoremreach.TheoremReach;


public class TrsurveysPlugin implements FlutterPlugin, MethodCallHandler {
  private MethodChannel channel;
  private Registrar registrar;
  private Activity activity;

  @Override
  public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
    channel = new MethodChannel(flutterPluginBinding.getFlutterEngine().getDartExecutor(), "trsurveys");
    channel.setMethodCallHandler(this);
  }

When I try to debug my app it shows me the following errors

    private TrsurveysPlugin(Activity activity) {
        this.activity = activity;
    }

  public static void registerWith(Registrar registrar) {
    final MethodChannel channel = new MethodChannel(registrar.messenger(), "trsurveys");
    channel.setMethodCallHandler(new TrsurveysPlugin(registrar.activity()));
  }

  @Override
  public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
    if (call.method.equals("init")) {
      String apiKey = call.argument("apiKey");
      TheoremReach.initWithApiKeyAndUserIdAndActivityContext(apiKey, "USER_ID", activity);
    }
  }

  @Override
  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
    channel.setMethodCallHandler(null);
  }
}

When I try to debug my app I get the following errors: 

error: constructor TrsurveysPlugin in class TrsurveysPlugin cannot be applied to given types;
    flutterEngine.getPlugins().add(new com.example.trsurveys.TrsurveysPlugin());
                                   ^
  required: Activity
  found: no arguments
  reason: actual and formal argument lists differ in length

...path/Downloads/TheoremReach-error/example/android/app/src/main/java/com/example/trsurveys_example/MainActivity.java:11: error: incompatible types: MainActivity cannot be converted to FlutterEngine
    GeneratedPluginRegistrant.registerWith(this);
                                       ^

This is the code that appears in my GeneratedPluginRegistrant.java file. 

package io.flutter.plugins;

import androidx.annotation.Keep;
import androidx.annotation.NonNull;

import io.flutter.embedding.engine.FlutterEngine;

@Keep
public final class GeneratedPluginRegistrant {
  public static void registerWith(@NonNull FlutterEngine flutterEngine) {
    flutterEngine.getPlugins().add(new com.example.trsurveys.TrsurveysPlugin());
  }
}

While making the Plugin I have tried deleting the GeneratedPluginRegistrant.java file but every time it gets generated with the same configurations.

javaandroidflutterdartandroid-native-library


Solution 1:[1]

Open your project manifest file and remove this Lines

meta-data
android:name=”flutterEmbedding”
android:value=”2?

Then build and run it again.

Solution 2:[2]

This happened to me when upgrading a repository from older flutter version to the newer one. I followed the official flutter link for the migration.

I made appropriate changes on the android manifest file. Namely:

  1. Remove android:name attribute from <application> tag
  2. Change android:name of the single <activity> to android:name="io.flutter.embedding.android.FlutterActivity"
  3. Add <meta-data android:name="flutterEmbedding" android:value="2"/> as child of tag

However, I didn't change any code on the MainActivity which caused the error. The MainActivity was using older imports which was incompatible with the above three changes.

Final manifest file:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="co.appbrewery.magic8ball">
<uses-permission android:name="android.permission.INTERNET"/>
<application
    android:label="magic_8_ball"
    android:icon="@mipmap/ic_launcher">
    <activity
        android:name="io.flutter.embedding.android.FlutterActivity"
        android:launchMode="singleTop"
        android:theme="@style/LaunchTheme"
        android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density"
        android:hardwareAccelerated="true"
        android:windowSoftInputMode="adjustResize">
        <meta-data android:name="flutterEmbedding" android:value="2"/>
        <meta-data
            android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
            android:value="true" />
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>
            <category android:name="android.intent.category.LAUNCHER"/>
        </intent-filter>
    </activity>
</application>

Deleting the MainActivity resolved the issue for me.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Asendo
Solution 2 Illegal Argument

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