how to setup "Main Class" in "Run Configurations" in Eclipse

Solution 1:

Put the (fully qualified) name of the class containing main. For example, if you want to use moveposition2's main (and not moveposition1's) then you'd enter:

com.pre.moveposition2

Also, clicking on "Search..." should give you a list of classes that contain main() methods that you can choose from.

Solution 2:

If both classes have a main() method, you can only run one at a time, since they are effectively two distinct programs.

So, in the Run Configuration, you choose either moveposition1 or moveposition2. If you later want to run the other one, just right-click on it and select Run As...->Java Application. You will now have two run configurations for your project.