Android横幅广告导致崩溃

Question

我正在尝试在我的应用程序上运行横幅广告，但它不断崩溃。我在某个地方犯了错误，但我只是找到了它。由于格式规则的原因，我在发布问题时也遇到了麻烦，因此我不得不发布代码的 png 图像。对于给您带来的不便，请接受我的歉意。事情是这样的： build.gradle（项目）

buildscript {
    
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:7.1.1'

        

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        mavenCentral()
    }
}

build.gradle（模块）：

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'androidx.appcompat:appcompat:1.0.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.vectordrawable:vectordrawable:1.0.0'
    implementation 'com.google.android.gms:play-services-ads:20.6.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0'
    implementation 'androidx.recyclerview:recyclerview:1.0.0'
    implementation 'com.google.android.material:material:1.0.0'
    implementation 'androidx.preference:preference:1.0.0'
    implementation 'androidx.legacy:legacy-preference-v14:1.0.0'
    implementation 'androidx.annotation:annotation:1.0.0'
    implementation 'androidx.legacy:legacy-support-v13:1.0.0'
    implementation 'com.google.android.gms:play-services-ads:20.6.0'
}

manifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.xtenalyze.android.myapplication">
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <supports-screens android:resizeable="true"
        android:smallScreens="true"
        android:normalScreens="true"
        android:largeScreens="true"
        android:xlargeScreens="true"
        android:anyDensity="true"/>


    <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.NoActionBar">

        <meta-data
            android:name="com.google.android.gms.ads.APPLICATION_ID"
            android:value="ca-app-pub-8169421610831095~xxxxxxxx"/>




        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:theme="@style/AppTheme.Launcher">
            <meta-data
                android:name="preloaded_fonts"
                android:resource="@array/preloaded_fonts" />

            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>


        <activity android:name=".FlashcardActivity">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>
        <activity
            android:name=".SettingsActivity"
            android:theme="@style/AppTheme"
            android:label="Settings"
            android:parentActivityName=".MainActivity">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>
        <activity
            android:name=".AboutActivity"
            android:theme="@style/AppTheme"
            android:label="@string/About"
            android:parentActivityName=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />

        </activity>


        <service android:name=".BackgroundMusic"/>


    </application>


</manifest>

flashcard.xml（我想要显示广告的页面）：

<?xml version="1.0" encoding="utf-8"?>


<androidx.constraintlayout.widget.ConstraintLayout xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <ImageView
        android:id="@+id/FlashcardimageView"
        android:layout_width="326dp"
        android:layout_height="290dp"
        android:layout_marginBottom="32dp"
        android:layout_marginEnd="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_weight="1"
        android:src="@mipmap/ic_launcher"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.506"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.45" />

    <TextView
        android:id="@+id/FlashcardTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="16dp"
        android:text="Mark"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        android:textSize="50sp"
        app:fontFamily="@font/atma_semibold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.544"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.853" />

    <com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="44dp"
        android:layout_marginRight="44dp"
        android:layout_marginBottom="28dp"
        app:adSize="BANNER"
        app:adUnitId="ca-app-pub-3940256099942544/6300978111"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"></com.google.android.gms.ads.AdView>


</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java：

package com.xtenalyze.android.myapplication;

import android.content.Intent;
import android.content.SharedPreferences;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import androidx.preference.PreferenceManager;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.MobileAds;
import com.google.android.gms.ads.initialization.InitializationStatus;
import com.google.android.gms.ads.initialization.OnInitializationCompleteListener;


public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    private View view;
    private static final String TAG = "MainActivity";
    private AdView mAdView;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        setTheme(R.style.AppTheme);
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        MobileAds.initialize(this, new OnInitializationCompleteListener() {
            @Override
            public void onInitializationComplete(InitializationStatus initializationStatus) {
            }
        });

        mAdView = findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest.Builder().build();
        mAdView.loadAd(adRequest);


        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        mLayoutManager = new GridLayoutManager(this, 2);
        mRecyclerView.setLayoutManager(mLayoutManager);

        // specify an adapter (see also next example)
        String[] myDataset = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};
        mAdapter = new MyAdapter(myDataset);
        mRecyclerView.setAdapter(mAdapter);
        SharedPreferences musicPref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        final String musicSettingVal = musicPref.getString(SettingsActivity.KEY_MUSIC_CONN, "");
//        Log.d(TAG,"Testing musicPref "+musicSettingVal);
        if (musicSettingVal.equals("On")) {
            startService(new Intent(this, BackgroundMusic.class));

        } else {
            stopService(new Intent(this, BackgroundMusic.class));
        }


    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.prefmenu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.settings:
                //Toast.makeText(this, "ADD!", Toast.LENGTH_SHORT).show();
                Intent i = new Intent(this, SettingsActivity.class);
                startActivity(i);
                return true;
            case R.id.about:
                Intent intent = new Intent(this, AboutActivity.class);
                startActivity(intent);
            default:
                return super.onOptionsItemSelected(item);
        }

    }

    @Override
    protected void onDestroy() {

        if (this.isFinishing()) {

            stopService(new Intent(this, BackgroundMusic.class));
            super.onDestroy();
        }

    }


    }

调试终端：

D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.xtenalyze.android.myapplication, PID: 19633
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xtenalyze.android.myapplication/
com.xtenalyze.android.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual
method 'void com.google.android.gms.ads.AdView.loadAd(com.google.android.gms.ads.AdRequest)' on a null object
reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3720)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3887)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:140)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:100)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2317)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:263)
at android.app.ActivityThread.main(ActivityThread.java:8283)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:612)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1006)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void
com.google.android.gms.ads.AdView.loadAd(com.google.android.gms.ads.AdRequest)' on a null object reference
at com.xtenalyze.android.myapplication.MainActivity.onCreate(MainActivity.java:50)
at android.app.Activity.performCreate(Activity.java:8146)
at android.app.Activity.performCreate(Activity.java:8130)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3689)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3887)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:140)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:100)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2317)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:263)
at android.app.ActivityThread.main(ActivityThread.java:8283)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:612)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1006)
I/Process: Sending signal. PID: 19633 SIG: 9
Disconnected from the target VM, address: 'localhost:37553', transport: 'socket'

Answer 1

此代码

  <com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="44dp"
        android:layout_marginRight="44dp"
        android:layout_marginBottom="28dp"
        app:adSize="BANNER"
        app:adUnitId="ca-app-pub-3940256099942544/6300978111"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"></com.google.android.gms.ads.AdView>

应在“ active_main.xml”中，不在“ flashcard.xml”中，不清楚如何连接它们。