Android - 在setAdapter的NullPointerException ViewPager

Question

我有一个小问题。我试图创建一个带有片段的布局，但是当我调用setAdapter方法时，我有一个Java NullPointerException，我找不到该错误。 谢谢大家！

类代码

public class Agenda extends FragmentActivity{ 

PagerAdapter mPagerAdapter; 

ViewPager mViewPager; 

protected void onCreate(Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 

    setContentView(R.layout.agenda_sw); 

    mPagerAdapter = new PagerAdapter(getSupportFragmentManager()); 

    // Set up the ViewPager with the sections adapter. 
    mViewPager = (ViewPager) findViewById(R.id.agendaPager); 

    mViewPager.setAdapter(mPagerAdapter); //Line 32, the error is on this line. 

} 

XML代码

<android.support.v4.view.ViewPager 
xmlns:android="http://schemas.android.com/apk/res/android" 
android:id="@+id/agenda_sw" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
/> 

logcat的

03-04 11:06:14.686: E/AndroidRuntime(1356): FATAL EXCEPTION: main 
03-04 11:06:14.686: E/AndroidRuntime(1356): java.lang.RuntimeException: Unable to start activity ComponentInfo{conf.main/conf.main.Agenda}: java.lang.NullPointerException 
... 
03-04 11:06:14.686: E/AndroidRuntime(1356): Caused by: java.lang.NullPointerException 
03-04 11:06:14.686: E/AndroidRuntime(1356): at conf.main.Agenda.onCreate(Agenda.java:32) 

Answer 1

错误viewpager ID。您用xml写的：

android:id="@+id/agenda_sw" 

但是在代码中您可以找到R.id.agendaPager并且应该为R.id.agenda_sw。