Answer 1

In web development Java is usually used as a backend language. Popular frameworks include Spring, Struts, JSF, Play (mainly a Scala framework), Vaadin, GWT, and Wicket.

Java isn’t usually used as a front end language but using GWT, Vaadin, or Wicket you can use it as one.

Xcode is the Apple ide for making iOS apps using obj c or swift.

React Native is for JavaScript not Java.

Flutter is a Java ui framework for Android and IOS.