E/WindowManager: android.view.WindowLeaked: Activity com.example.whoosisstudent.MainActivity has leaked window DecorView@ab4f22b[MainActivity] that was originally added here
at android.view.ViewRootImpl.(ViewRootImpl.java:539)
at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:346)
at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:94)
at android.app.Dialog.show(Dialog.java:329)
at android.app.DialogFragment.onStart(DialogFragment.java:513)
at android.app.Fragment.performStart(Fragment.java:2548)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1334)
at android.app.FragmentManagerImpl.addAddedFragments(FragmentManager.java:2431)
at android.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2210)
at android.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2166)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2067)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:738)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6810)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)
activity的泄漏，看似和这个文章类似，dialog引起的
https://www.cnblogs.com/xiajf/p/4014286.html