adb 命令 dumpsys activity , 用来看 task 中的activity。

在模拟器上把这个应用程序再次跑起来，用“adb shell dumpsys activity”命令再来查看一下系统运行的的任务，就会看到：

 Running activities (most recent first):
     TaskRecord{4069c020 #4 A shy.luo.task.sub.activity}
       Run #2: HistoryRecord{40725040 shy.luo.task/.SubActivity}
     TaskRecord{40695220 #3 A shy.luo.task.main.activity}
       Run #1: HistoryRecord{406b26b8 shy.luo.task/.MainActivity}
     TaskRecord{40599c90 #2 A com.android.launcher}
       Run #0: HistoryRecord{40646628 com.android.launcher/com.android.launcher2.Launcher}