problem description

small demo
Performing hot reload.
Syncing files to device OPPO R11
Reloaded 0 of 419 libraries in 401ms.
E/flutter (2440): [ERROR:flutter/shell/common/shell.cc
E/flutter (2440): MissingPluginException (No implementation found for method getBatteryLevel on channel samples.flutter.io/battery)
E/flutter (2440):-sharp0 MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:291:7)

* * I ran the official example code, and I can get the battery information correctly, but the official code is new MethodCallHandler ()
I can"t use new MethodCallHandler () in my own project so that I can newMethodChannel.MethodCallHandler () * *

dart file

the environmental background of the problems and what methods you have tried

1.

related codes

/ / Please paste the code text below (do not replace the code with pictures)

package com.example.batterylevel;

import android.os.Bundle;
import io.flutter.app.FlutterActivity;
import io.flutter.plugin.common.MethodCall;
import io.flutter.plugin.common.MethodChannel;
import io.flutter.plugins.GeneratedPluginRegistrant;



import android.content.ContextWrapper;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;

public class MainActivity extends FlutterActivity {
  private static final String CHANNEL = "com.example.batterylevel/battery";
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    GeneratedPluginRegistrant.registerWith(this);
    new MethodChannel(getFlutterView(),CHANNEL).setMethodCallHandler(
            new MethodChannel.MethodCallHandler() {
              @Override
              public void onMethodCall(MethodCall call, MethodChannel.Result result) {

                if (call.method.equals("getBatteryLevel")) {
                  int batteryLevel = getBatteryLevel();

                  if (batteryLevel != -1) {
                    result.success(batteryLevel);
                  } else {
                    result.error("UNAVAILABLE", "Battery level not available.", null);
                  }
                } else {
                  result.notImplemented();
                }
              }
            }
    );
  }

  static const platfrom = const MethodChannel("com.example.batterylevel/battery");
  String _batteryLevel ="";

  Future<Null> _getBatteryLevel() async{
    String batteryLevel;
    try{
      final int result = await platfrom.invokeMethod("getBatteryLevel");
      batteryLevel = "$result %";
    } on PlatformException catch(e){
      batteryLevel=":$e.message";
    }
    setState(() {
      _batteryLevel =_batteryLevel;
    });
  }

what result do you expect? What is the error message actually seen?