Why do I choose spring over angularjs as angularjs is more robust and fast?

Spring and angularjs are not exchangeable. In other words, choosing spring does not mean you will not use angular and vice versa.

Spring is a Java framework which you can use to develop the backend of your application while angularjs is a javascript framework which is used in the frontend. 

So, you can develop the backend in java using spring framework (or any other language and framework) and the front end in Angularjs.

Hope that help.