我正在尝试创建一个带有抽屉导航和四个 fragment 的应用程序。因此,当我从抽屉导航中选择选项时,会显示 fragment 的 View 。现在,我为 View 创建了某些按钮,但每当我尝试在代码中初始化它们时,我都会收到下面粘贴的运行时错误。
当我执行 Command + 单击那些 ids R.id.bIndexOutOfBounds 按钮时,它显示了多个声明。我不知道如何选择一个特定的声明,为什么 android studio 在只有 1 个文件时寻找 4 个不同的 fragment_crash.xml 文件( fragment 的布局文件)。
如果有人知道如何只获取 1 个 layout_crash.xml 文件,请帮助我。
04-01 14:34:10.256 2067-2067/com.example.android.navigationdrawer E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.android.navigationdrawer, PID: 2067
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.navigationdrawer/com.example.android.navigationdrawer.NavigationDrawerActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
at com.example.android.navigationdrawer.CrashFragment.onCreateView(CrashFragment.java:56)
at android.app.Fragment.performCreateView(Fragment.java:2053)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:894)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
at android.app.BackStackRecord.run(BackStackRecord.java:833)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1452)
at android.app.Activity.performStart(Activity.java:5948)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
最佳答案
您应该在 bIndexOutOfBounds = (Button) getView().findViewById(R.id.bIndexOutOfBounds);
中使用“view”而不是“getView()”
getView()
将返回由 onCreateView()
返回的 fragment 的 Root View ,因此您无法通过 getView()
获取 View > 在 onCreateView()
关于Android Studio - 无法选择声明,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29401507/