In Android, I would startActivtyForResult, a new activity would start. When that new activity was finished, it would setResult and trigger onActivityResult in the first activity.
What is the equivalent to that in plain Java? I want to call a new uibinder owner class, in that panel once I have a result, I want to come back to the first class and display the result.
This mechanism is called a Callback. You can implement your desired functionality using Observer desing pattern in Java.
Observer design pattern