Question

实际上，我正在努力制作一款免费且付费的应用程序。当我使用简单的findViewById方法绑定时，它工作正常。但是当我尝试添加butterKnife时，我拼命地坚持使用butterKnife。

我正在尝试通过MainActivity.java文件中的butterknife绑定绑定内容（例如AdMob OR Button）。但它首先显示Nullpointer异常错误，它显示在AdMob对象nullpointer异常上。我运行干净的项目然后它显示在button.onClickListener Nullpointer异常。

请帮帮我......

以下是错误：显示AdMob nullpointerException：

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);
        }
    }
}

2-MainActivity.java

<?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>

3- activity_main.xml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>

4-清单文件

function map(n,i,o,r,t){return i>o?i>n?(n-i)*(t-r)/(o-i)+r:r:o>i?o>n?(n-i)*(t-r)/(o-i)+r:t:void 0}

Answer 1

你错过了

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

更改以下代码

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

更新

的依赖关系

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

Answer 2

正确答案是我使用了gradle 2.2.0或更新版本。所以感谢JakeWarton github链接[https://github.com/JakeWharton/butterknife]which清楚地描述了Butterknife与新版gradle的集成。因此，在较新版本的gradle中逐步实施butterKnife如下：

1-首先，添加classpath＆＃39; com.neenbedankt.gradle.plugins：android-apt：1.8＆＃39;依赖关系：

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

2-其次，添加build.gradle应用程序模块butterKnife

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

总而言之，当我们使用gradle 2.2.0或更新版本时，我们需要添加上述更改。这就是它，很容易...... :)

Answer 3

我遇到了类似的问题。当我在资源文件中仔细检查时，我的活动有两个资源文件：

\res\layout\activity_main_lauch.xml

\res\layout-v21\activity_main_lauch.xml

我正在修改单个文件，因此它抛出了错误。当我在两个文件中应用更改时，它开始工作。

Answer 4

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

在几行代码后

设置此代码，有时加载广告和Adview会花费一些时间。因此，在几行代码之后添加此代码，以获取结果并尝试再次运行。

Answer 5

确保仅在setContentView命令之后添加三个adMob行

否则-此命令将返回 null 值：

 mAdView = **findViewById(R.id.adView);**

正确命令序列的示例：

setContentView(R.layout.activity_item_list);  // <== make asure this comes **BEFORE** the Admob mAdView commands

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

如何使用Butterknife解决NullPointerException void com.google.android.gms.ads.AdView.loadAd（com.google.android.gms.ads.AdRequest）

5 个答案: