和视频中写的一模一样,但是总报空指针异常是怎么回事?
2019-11-10 20:11:16.327 4931-4931/com.example.himalaya E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.himalaya, PID: 4931
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.himalaya/com.example.himalaya.PlayerActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object[] java.util.Collection.toArray()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object[] java.util.Collection.toArray()' on a null object reference
at java.util.ArrayList.addAll(ArrayList.java:562)
at com.example.himalaya.adapters.PlayTrackPagerAdapter.setData(PlayTrackPagerAdapter.java:54)
at com.example.himalaya.PlayerActivity.onListLoaded(PlayerActivity.java:369)
at com.example.himalaya.presenters.PlayerPresenter.getPlayList(PlayerPresenter.java:181)
at com.example.himalaya.PlayerActivity.onCreate(PlayerActivity.java:89)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
空指针是最好解决的呀,把这个地方的代码贴出来呗。PlayTrackPagerAdapter.java 第54行前后大部分。