您好,我在应用程序中添加粉丝横幅时遇到问题,出现错误
我在布局中添加了横幅容器
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.kimali.bhirod.MainActivity">
<LinearLayout
android:id="@+id/banner_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
/>
然后我实例化广告-查看并将其加载到我的活动中
public class MainActivity extends AppCompatActivity {
private AdView adView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Instantiate an AdView view
adView = new AdView(this, "153676755260608_153679028593714", AdSize.BANNER_HEIGHT_50);
// Find the Ad Container
LinearLayout adContainer = (LinearLayout) findViewById(R.id.banner_container);
// Add the ad view to your activity layout
adContainer.addView(adView);
// Request an ad
adView.loadAd(); setContentView(R.layout.activity_main);
但是当我尝试在设备上测试代码时,出现此错误
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kimali.bhirod/com.kimali.bhirod.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.addView(android.view.View)' on a null object reference
谢谢
最佳答案
您的setContentView(R.layout.your_layout)
中没有onCreate()
。在不夸大布局的情况下,findViewById
将返回null。