如何解決NullPointerException void com.google.android.gms.ads.AdView.loadAd（com.google.android.gms.ads.AdRequest）with Butterknife

Question

實際上，我試圖製作一個免費和付費的應用程序。當我使用簡單的findViewById方法綁定時，它工作正常。但是當我嘗試添加黃油菜刀時，我拼命地用黃油菜刀卡住了。

我想通過在MainActivity.java文件中的butterknife綁定來綁定內容（如AdMob或Button）。但它首先顯示Nullpointer異常錯誤，它顯示AdMob對象空指針異常。我運行乾淨的項目，然後它顯示button.onClickListener Nullpointer異常。

請幫我...

以下是錯誤：這說明AdMob的NullPointerException異常：

09-08 19:04:30.860 19466-19466/? E/AndroidRuntime: FATAL EXCEPTION: main 
                Process: com.santossingh.jokeapp.free, PID: 19466 
                java.lang.RuntimeException: Unable to start activity ComponentInfo{com.santossingh.jokeapp.free/com.santossingh.jokeapp.free.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:2416) 
                 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                 at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                 at android.os.Handler.dispatchMessage(Handler.java:102) 
                 at android.os.Looper.loop(Looper.java:148) 
                 at android.app.ActivityThread.main(ActivityThread.java:5417) 
                 at java.lang.reflect.Method.invoke(Native Method) 
                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
                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.santossingh.jokeapp.free.MainActivity.onCreate(MainActivity.java:62) 
                 at android.app.Activity.performCreate(Activity.java:6237) 
                 at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
                 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) 
                 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  
                 at android.app.ActivityThread.-wrap11(ActivityThread.java)  
                 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  
                 at android.os.Handler.dispatchMessage(Handler.java:102)  
                 at android.os.Looper.loop(Looper.java:148)  
                 at android.app.ActivityThread.main(ActivityThread.java:5417)  
                 at java.lang.reflect.Method.invoke(Native Method)  
                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)  
                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)  
09-08 19:04:35.652 837-2192/system_process E/Surface: getSlotFromBufferLocked: unknown buffer: 0xf2cf6c90 
09-08 19:04:56.030 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:06:20.986 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:07:41.011 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:09:01.042 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:10:20.982 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:11:46.019 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:13:06.051 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:14:41.018 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 
09-08 19:16:06.047 837-853/system_process E/BluetoothAdapter: Bluetooth binder is null 

2-MainActivity.java

public class MainActivity extends AppCompatActivity implements AsyncResponse{ 

    @BindView(R.id.avi) AVLoadingIndicatorView avLoadingIndicatorView; 
    @BindView(R.id.button_jokeTeller) Button button_JokeTeller; 
    @BindView(R.id.instruction_TextView) 
    TextView instruction; 
    @BindView(R.id.container) RelativeLayout relativeLayout; 
    @BindView(R.id.adView) AdView adView; 
    @BindView(R.id.progressBar) LinearLayout linearLayout; 

    private InterstitialAd mInterstitialAd; 
    EndpointsAsyncTask endpointsAsyncTask; 
    private static final String JOKE_TAG="joke"; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     ButterKnife.bind(this); 

     endpointsAsyncTask = new EndpointsAsyncTask(this); 

     AdRequest adRequestBanner = new AdRequest.Builder().build(); 
     adView.loadAd(adRequestBanner); 

     mInterstitialAd = new InterstitialAd(this); 
     mInterstitialAd.setAdUnitId(getString(R.string.interstitial_ad_unit_id)); 
     AdRequest adRequestInterstitial = new AdRequest.Builder().build(); 
     mInterstitialAd.loadAd(adRequestInterstitial); 

     button_JokeTeller.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       showInterstitial(); 
      } 
     }); 

     mInterstitialAd.setAdListener(new AdListener() { 
      @Override 
      public void onAdClosed() { 
       showProgressbar(true); 
       showJoke(); 
      } 

      @Override 
      public void onAdFailedToLoad(int errorCode) { 
       Toast.makeText(getApplicationContext(), "Ad failed to load! error code: " + errorCode, Toast.LENGTH_SHORT).show(); 
      } 

      @Override 
      public void onAdLeftApplication() { 
       showProgressbar(true); 
       Toast.makeText(getApplicationContext(), "Ad left application!", Toast.LENGTH_SHORT).show(); 
      } 

      @Override 
      public void onAdOpened() { 
       Toast.makeText(getApplicationContext(), "Ad is opened!", Toast.LENGTH_SHORT).show(); 
      } 
     }); 
    } 
    private void showInterstitial() { 
     if (mInterstitialAd.isLoaded()) { 
      mInterstitialAd.show(); 
     } 
    } 

    public void showJoke(){ 
     endpointsAsyncTask.execute(getString(R.string.keyword)); 
    } 

    @Override 
    public void processFinish(String result) { 
     Intent intent = new Intent(this, JokeActivity 
       .class) 
       .putExtra(JOKE_TAG, result); 
     showProgressbar(false); 
     startActivity(intent); 
    } 

    public void showProgressbar(boolean a){ 
     if(a==true){ 
      relativeLayout.setVisibility(View.GONE); 
      linearLayout.setVisibility(View.VISIBLE); 
     }else{ 
      linearLayout.setVisibility(View.GONE); 
      relativeLayout.setVisibility(View.VISIBLE); 
     } 
    } 
} 

3- activity_main.xml中文件

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout 
    android:id="@+id/activity_main" 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:background="#0e73a6" 
    android:padding="10dp" 
    tools:context="com.santossingh.jokeapp.free.MainActivity" 
    xmlns:ads="http://schemas.android.com/apk/res-auto" 
    xmlns:app="http://schemas.android.com/apk/res-auto"> 
    <LinearLayout 
     android:id="@+id/progressBar" 
     android:layout_width="match_parent" 
     android:gravity="center" 
     android:layout_height="match_parent"> 

    <com.wang.avi.AVLoadingIndicatorView 
     android:id="@+id/avi" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     style="@style/AVLoadingIndicatorView" 
     android:visibility="visible" 
     app:indicatorName="BallPulseIndicator" 
    /> 
</LinearLayout> 
    <RelativeLayout android:layout_width="match_parent" 
        android:layout_height="match_parent" 
        android:id="@+id/container"> 
     <TextView 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content" 
      android:text="@string/instructions" 
      android:textColor="#fff" 
      android:id="@+id/instruction_TextView" 
     /> 

     <Button android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:id="@+id/button_jokeTeller" 
       android:layout_below="@+id/instruction_TextView" 
       android:text="@string/button_text" 
     /> 

     <!-- view for AdMob Banner Ad --> 
     <com.google.android.gms.ads.AdView 
      android:id="@+id/adView" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_alignParentBottom="true" 
      android:layout_centerHorizontal="true" 
      ads:adSize="BANNER" 
      ads:adUnitId="@string/banner_ad_unit_id"/> 
    </RelativeLayout> 

</RelativeLayout> 

4-清單文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"> 

    <uses-permission android:name="android.permission.INTERNET"/> 
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> 

    <application> 
     <activity android:name="com.santossingh.jokeapp.free.MainActivity" 
     > 
      <!-- This meta-data tag is required to use Google Play Services. --> 
      <meta-data 
       android:name="com.google.android.gms.version" 
       android:value="@integer/google_play_services_version"/> 

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

    <activity 
     android:name="com.google.android.gms.ads.AdActivity" 
     android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize" 
     android:theme="@android:style/Theme.Translucent"/> 
</manifest> 

Answer 1

你缺少

adView = (AdView)this.findViewById(R.id.adView); 

更改代碼如下

AdRequest adRequestBanner = new AdRequest.Builder().build(); 
**adView = (AdView)this.findViewById(R.id.adView);** 
     adView.loadAd(adRequestBanner); 

更新依賴於

dependencies { compile 'com.jakewharton:butterknife:8.0.1' apt 'com.jakewharton:butterknife-compiler:8.0.1' } 

Answer 2

它正確的答案是，我使用gradle 2.2.0或更新的版本。所以感謝JakeWarton的github鏈接[https://github.com/JakeWharton/butterknife]which清楚地描述了Butterknife與新版gradle的整合。 結果butterKnife的gradle這個步驟的較新版本一步執行如下命令：

1 - 首先，添加類路徑「com.neenbedankt.gradle.plugins：Android的貼切：1.8」的依賴關係：

dependencies { 
     .... 
     classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8' 
} 

2-其次，加入的build.gradle應用模塊butterKnife

dependencies { 
    .... 
    compile 'com.jakewharton:butterknife:8.4.0' 
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.4.0' 
} 

所以，在所有的結論是，當我們使用gradle這個2.2.0或更新版本，那麼我們需要添加上述變化。就是這樣，那麼容易...... :)

Answer 3

我面臨類似的問題。當我在資源文件中密切檢查有我的活動兩個資源文件：

\res\layout\activity_main_lauch.xml

\res\layout-v21\activity_main_lauch.xml

我修改一個文件，因此它被扔的錯誤。當我在兩個文件中應用更改時，它開始工作。