当我尝试onKeyDown（）时，如何将Android Java中的硬件按钮作为本机颤振来听，但它没有'；不行？

MainActivity.java

package com.example.trial;
import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugin.common.MethodChannel;

import android.view.KeyEvent;
import android.view.WindowManager;
import android.app.AlertDialog;
import android.content.DialogInterface;


public class MainActivity extends FlutterActivity {
  private static final String CHANNEL = "For sending hello";

  @Override
  public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
  super.configureFlutterEngine(flutterEngine);
    new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL)
        .setMethodCallHandler(
          (call, result) -> {
              System.out.println("Hellooo from JAAAAAAAAAAAAAAAAAAAAAVAAAAAAAAAAAAA");
            // Note: this method is invoked on the main thread.
             @Override
             boolean onKeyDown(int keyCode, KeyEvent event) {
                     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                       return super.onKeyDown(keyCode, event);
                     }
                     switch (keyCode) {
                       case KeyEvent.KEYCODE_MEDIA_PLAY:
                               yourMediaController.dispatchMediaButtonEvent(event);
                               return true;
                     }
                     return super.onKeyDown(keyCode, event);
             }
            
  }
}

所以问题是，我想在颤振应用程序中阅读硬件按钮，我尝试过使用硬件按钮插件，但它在前台不太起作用。所以我决定用本机语言编写代码，现在我无法使用keyDown（），因为它给了我以下错误

D:\Projects\trial\android\app\src\main\java\com\example\trial\MainActivity.java:28: error: ';' expected
            boolean onKeyDown(int keyCode, KeyEvent event) {
                             ^
D:\Projects\trial\android\app\src\main\java\com\example\trial\MainActivity.java:28: error: ';' expected
            boolean onKeyDown(int keyCode, KeyEvent event) {
                                                   ^
D:\Projects\trial\android\app\src\main\java\com\example\trial\MainActivity.java:28: error: not a statement
            boolean onKeyDown(int keyCode, KeyEvent event) {
                                                    ^
D:\Projects\trial\android\app\src\main\java\com\example\trial\MainActivity.java:28: error: ';' expected
            boolean onKeyDown(int keyCode, KeyEvent event) {
                                                         ^
4 errors

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s
Exception: Gradle task assembleDebug failed with exit code 1

对不起，如果这是一个新手问题，如果这是一个错误的方式，请建议我一些其他的方式，以听取在前景/背景本身的按钮

提前谢谢你