Understanding information about threads in Android Studio

Question

During debugging on a breakpoint one can notice on the left of the Debug panel a dropdown list which lists various threads in the following format:

"main"@3,573 in group "main":WAIT
"pool-1-thread-1"@3,665 in group "main":WAIT

I have the following questions:

1) What does the four digit number mean (e.g. 3,573)? Process number?

2) What is meant here by group?

Answer 1

The thread display is defined by the UI.

If you are using Intellij @### is the line number. You can customize this in "Customize Thread View"

From the Thread class documentation:

State: http://developer.android.com/reference/java/lang/Thread.State.html

Thread Groups: https://books.google.com/books?id=ka2VUBqHiWkC&pg=PA288&lpg=PA288&dq=Avoid+thread+groups&source=bl&ots=yZGnRmr6P3&sig=qH791dt7d0PrPeG7D5SH-4Yzg3Q&hl=en&sa=X&ved=0ahUKEwjK2e7DgbvJAhXETCYKHRoFAMIQ6AEIJDAB#v=onepage&q=Avoid%20thread%20groups&f=false