Yes, showing some code would be helpful. Show the "calling block" in the 1st JFrame and as much of the code of the 2nd JFrame to show how the value you want to share is captured and stored or communicated to the 1st JFrame.
I'm also wondering about this statement, "This is because 2nd Jframe starts working only when calling block in 1st JFrame executes completely," which may be based on some behavior you've observed, so it would be helpful if you'd describe that better.
Using a JFrame for the second dialog may not be optimal. A JDialog may be better, but show the code and we'll talk more about that.