我是一个初学者到应用程序开发，我有这个第一个项目，我试图建立一个问答游戏。我一直试图运行这个应用程序的最长时间可能。我试图编辑我的Android manifest.xml根据这里的解决方案，但没有工作
C：\用户\管理员\桌面\教育应用\应用\src\main\java\com\示例\趣味拼写\游戏活动。java：48：错误：包R不存在setContentView（R. layout. activity_game
下面是我的清单. xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sinanli.funspelling">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".SettingsActivity"
            android:label="@string/title_activity_settings"
            android:parentActivityName=".MainActivity"
            android:theme="@style/AppTheme.NoActionBar">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.sinanli.funspelling.MainActivity" />
        </activity>
        <activity
            android:name=".GameActivity"
            android:label="@string/title_activity_game"
            android:parentActivityName=".MainActivity"
            android:theme="@style/AppTheme.NoActionBar">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.sinanli.funspelling.MainActivity" />
        </activity>
        <activity
            android:name=".ScoreActivity"
            android:label="@string/title_activity_score"
            android:parentActivityName=".MainActivity"
            android:theme="@style/AppTheme.NoActionBar">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.sinanli.funspelling.MainActivity" />
        </activity>
    </application>`

</manifest>

我的www.example.com出现错误activity.java with the error

package com.example.funspelling;

import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.preference.PreferenceManager;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import android.R;

import java.util.Collections;
import java.util.List;

public class GameActivity extends AppCompatActivity {

    private TextView questionT;
    private ImageView foodImage;
    private TextView timeT;
    private EditText inputT;
    private Button buttonC;

    private CountDownTimer count;
    private SharedPreferences prefs;
    private AssetManager assetManager;
    private SoundManager soundManager;
    private int clap;

    private String rightAnswer;
    private String alertTitle;
    private int rightAnswerCount;
    private int quizCount = 1;
    private List<String> foodNames;
    private String difOption;
    private String musicOption;

    static private final int QUIZ_COUNT = 5;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_game);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        questionT = (TextView) findViewById(R.id.questionText);
        foodImage = (ImageView) findViewById(R.id.foodImage);
        timeT = (TextView) findViewById(R.id.timeText);
        inputT = (EditText) findViewById(R.id.inputText);
        buttonC = (Button) findViewById(R.id.button);

        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
        difOption = prefs.getString("difSelection","1");
        assetManager = new AssetManager(this, difOption);
        foodNames = assetManager.allFoodNames(difOption);

        soundManager = new SoundManager(this);
        clap = soundManager.addSound(R.raw.clap);

        musicOption = prefs.getString("musicSelection", "On");

        showNextQuiz();
        count = new CountDownTimer(10 * 1000, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                timeT.setText("Seconds Remaining: " + millisUntilFinished / 1000);
            }

            @Override
            public void onFinish() {
                timeT.setText("Done");
                buttonC.performClick();
            }
        };
        count.start();
    }

    public void showNextQuiz () {
        questionT.setText("Question " + quizCount + " Out of " + QUIZ_COUNT);

        Collections.shuffle(foodNames);
        foodImage.setImageDrawable(assetManager.imageForFood(foodNames.get(0)));
        rightAnswer = foodNames.get(0);

        foodNames.remove(0);
        Collections.shuffle(foodNames);
    }

    public void checkAnswer(View view) {
        String answer = inputT.getText().toString();
        inputT.setText("");

        if (answer.equals(rightAnswer)){
            alertTitle = "Correct!";
            rightAnswerCount++;
            if (musicOption.equals("On")){
                soundManager.play(clap);
            }
        } else {
            alertTitle = "Wrong...";
        }

        prefs = getSharedPreferences("value", MODE_PRIVATE);
        prefs.edit().putInt("Score", rightAnswerCount * 10).apply();

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        if (quizCount == QUIZ_COUNT) {
            count.cancel();
            builder.setTitle("Game Over");
            builder.setMessage("Score: " + rightAnswerCount * 10);
            builder.setPositiveButton("Close", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Intent intent = new Intent(getApplicationContext(), MainActivity.class);
                    startActivity(intent);
                }
            });
        } else {
            count.cancel();
            builder.setTitle(alertTitle);
            builder.setMessage("Answer : " + rightAnswer);
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    quizCount++;
                    showNextQuiz();
                    count = new CountDownTimer(10 * 1000, 1000) {
                        @Override
                        public void onTick(long millisUntilFinished) {
                            timeT.setText("Seconds Remaining: " + millisUntilFinished / 1000);
                        }

                        @Override
                        public void onFinish() {
                            timeT.setText("Done");
                            buttonC.performClick();
                        }
                    };
                    count.start();
                }
            });
        }
        builder.setCancelable(false);
        builder.show();
    }
}

我最初在intellij idea中制作了这个项目，我的gradle最初是4.2，当我改用android studio时，它为我提供了升级到7.4的选项
一次都没成功