Get info of current visible fragment(s) in android dumpsys

Get Info of Current Visible Fragment(s) in Android dumpsys

Android’s dumpsys command is a powerful tool for inspecting system processes and states. It provides a wealth of information about your device, including the UI hierarchy, which allows you to understand the current visible fragments in your application.

Understanding Fragments and the UI Hierarchy

Fragments: The Building Blocks of Android UI

• Fragments represent modular UI components within an Activity.
• They are reusable, allowing you to design complex user interfaces by combining various fragments.
• Fragments can be added, replaced, and removed dynamically, providing a flexible UI structure.

The UI Hierarchy: A Tree-like Structure

• Android’s UI is represented as a hierarchical tree, with the root being the Window object.
• Each node in the tree represents a UI element, such as Activities, Fragments, Views, and their children.
• dumpsys provides a textual representation of this tree, allowing you to inspect the hierarchy and identify visible fragments.

Extracting Fragment Information from dumpsys

To access information about visible fragments using dumpsys, follow these steps:

1. Enable Verbose Logging

adb shell setprop log.tag.ActivityManager verbose

2. Run dumpsys Activity

adb shell dumpsys activity

3. Identify the Target Fragment

In the output, search for the following pattern, which identifies fragments:

Fragment{ }: 

• : Unique ID assigned to the fragment.
• : Optional tag assigned to the fragment.
• : The fully qualified name of the fragment class.

The fragment is considered **visible** if the following conditions are met:

• It’s attached to an Activity (mHost field is not null).
• It’s added to the Activity’s View hierarchy (mView field is not null).
• It’s not hidden (mHidden field is false).

4. Example Output

...
ActivityRecord{42459b7 u0 a1603944}
  ...
  mFragments: FragmentManager{0x7f44a34}
    #0 Fragment{b37567f : com.example.app.MyFragment}
      mView: View{a1c0551 ...}
      mHidden: false
      mHost: Activity{42459b7}
  ...
...

In this example, the fragment Fragment{b37567f : com.example.app.MyFragment} is visible because:

• It’s attached to the Activity (mHost is not null).
• It’s added to the View hierarchy (mView is not null).
• It’s not hidden (mHidden is false).

Tips for Using dumpsys

• Use the grep command to filter output based on keywords, for example:

adb shell dumpsys activity | grep "MyFragment"

• Enable debug logging for specific components for more detailed information:

adb shell setprop log.tag.FragmentActivity VERBOSE

Conclusion

The dumpsys command is an invaluable tool for developers debugging and analyzing the UI structure of their Android applications. By understanding how to extract fragment information from dumpsys output, you can gain insights into the current UI state and identify potential issues with fragment visibility or lifecycle management.