Problem Description:

　　the user operation is waiting for “Building workspace” to complete

(this user action is waiting for the “building workspace” operation to complete.)

When eclipse detects that multiple tasks may need to use the same resource, there are potential version differences that need to be checked, so it requires that any of these potentially conflicting tasks be executed in order

This is called a “synchronous” operation. The reason is simply that you want to run a program, but its class may call another class that has not yet been compiled. Eclipse ensures that all related classes have been compiled

After compiling and checking, you can let your program run. So, just wait patiently. If you are sure that there is no conflict, you can run as in the launching profile

In the main class (or JUnit test) configuration, find “compile before running” and remove the check

project-> properties-> Builders will remove all the options with validator, and then save everything