FragmentActivity.getSupportFragmentManager（）'null对象引用

Question

每当我尝试单击我的listview以进入下一个活动时，我都会收到空对象引用。它应该是第31行。因此，这一行“adapter = new ViewPagerAdapter（myContext.getSupportFragmentManager（），TitlesAuto，Numboftabs）;”

package android.evers.mickey.final_eindwerk_android; 
import android.app.Activity; 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.v4.app.FragmentActivity; 
import android.support.v4.view.ViewPager; 

/** 
* Created by Mickey on 22/01/16. 
*/ 
public class AutoSelected extends Activity { 
    ViewPagerAdapter adapter; 
    ViewPager pager; 
    SlidingTabLayout tabs; 
    CharSequence TitlesAuto[]={"Info","Picture", "Sound"}; 
    int Numboftabs = 3; 
    public FragmentActivity myContext; 


    @Nullable 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.auto_main_selected); 

     // Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs. 
     adapter = new ViewPagerAdapter(myContext.getSupportFragmentManager(),TitlesAuto,Numboftabs); 
     pager = (ViewPager) myContext.findViewById(R.id.pagerAuto); 

     // Assigning ViewPager View and setting the adapter 
     pager = (ViewPager) myContext.findViewById(R.id.pagerAuto); 
     pager.setAdapter(adapter); 

     // Assiging the Sliding Tab Layout View 

     tabs = (SlidingTabLayout) myContext.findViewById(R.id.tabsAuto); 
     tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width 

     // Setting Custom Color for the Scroll bar indicator of the Tab View 
     tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() { 
      @Override 
      public int getIndicatorColor(int position) { 
       return getResources().getColor(R.color.colorAccent); 
      } 
     }); 

     // Setting the ViewPager For the SlidingTabsLayout 
     tabs.setViewPager(pager); 
    }} 

，这是我的错误：

08-14 01:27:49.230 23389-23389/? I/art: Not late-enabling -Xcheck:jni (already on) 
08-14 01:27:49.273 23389-23389/? W/System: ClassLoader referenced unknown path: /data/app/android.evers.mickey.final_eindwerk_android-2/lib/x86 
08-14 01:27:49.280 23389-23396/? E/art: Failed writing handshake bytes (-1 of 14): Broken pipe 
08-14 01:27:49.280 23389-23396/? I/art: Debugger is no longer active 
08-14 01:27:49.384 23389-23403/? D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true 
08-14 01:27:49.467 23389-23403/? I/OpenGLRenderer: Initialized EGL, version 1.4 
08-14 01:27:49.483 23389-23403/? W/EGL_emulation: eglSurfaceAttrib not implemented 
08-14 01:27:49.483 23389-23403/? W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xabf3f100, error=EGL_SUCCESS 
08-14 01:27:54.069 23389-23389/android.evers.mickey.final_eindwerk_android W/PathParser: Points are too far apart 4.000000596046461 
08-14 01:27:55.273 23389-23389/android.evers.mickey.final_eindwerk_android W/PathParser: Points are too far apart 4.000000596046461 
08-14 01:27:55.479 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: {"id":"1","naam":"test","info":"dit is een test","merk":"porshe","bouwjaar":"0000-00-00","foto":"http:\/\/dtsl.ehb.be\/~mickey.evers\/android\/images\/auto1.png"} 
08-14 01:27:55.479 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: http://dtsl.ehb.be/~mickey.evers/android/images/auto1.png 
08-14 01:27:55.479 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: test 
08-14 01:27:55.479 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: {"id":"2","naam":"testfxfjj","info":"test2","merk":"testen","bouwjaar":"0000-00-00","foto":"http:\/\/dtsl.ehb.be\/~mickey.evers\/android\/images\/auto1.png"} 
08-14 01:27:55.481 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: http://dtsl.ehb.be/~mickey.evers/android/images/auto1.png 
08-14 01:27:55.481 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: testfxfjj 
08-14 01:27:55.481 23389-23389/android.evers.mickey.final_eindwerk_android I/System.out: [test, testfxfjj] 
08-14 01:27:56.205 23389-23389/android.evers.mickey.final_eindwerk_android D/AndroidRuntime: Shutting down VM 
08-14 01:27:56.205 23389-23389/android.evers.mickey.final_eindwerk_android E/AndroidRuntime: FATAL EXCEPTION: main 
                          Process: android.evers.mickey.final_eindwerk_android, PID: 23389 
                          java.lang.RuntimeException: Unable to start activity ComponentInfo{android.evers.mickey.final_eindwerk_android/android.evers.mickey.final_eindwerk_android.AutoSelected}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentManager android.support.v4.app.FragmentActivity.getSupportFragmentManager()' 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 'android.support.v4.app.FragmentManager android.support.v4.app.FragmentActivity.getSupportFragmentManager()' on a null object reference 
                           at android.evers.mickey.final_eindwerk_android.AutoSelected.onCreate(AutoSelected.java:31) 
                           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)  
08-14 01:32:56.222 23389-23389/? I/Process: Sending signal. PID: 23389 SIG: 9 

Answer 1

myContext是空的，所以当你打电话myContext.getSupportFragmentManager()你会得到一个空指针异常。

活动是一个上下文，所以你不需要持有上下文字段。改为拨打.getSupportFragmentManager()。

（噢，并删除myContext彻底使您不必在findViewById()通话死机一样。）