Xtend completely supports Java's type system: The primitive types as int or boolean are available as well as all classes and interfaces that reside on the classpath.
Java Generics are fully supported, such that you can define type parameters and type arguments in just the same way as in Java.
As Xtend classes compile to Java classes, you can integrate both Java classes in Xtend and Xtend classes in Java. Note that Xtend does not have an own syntax for interfaces, as the Java syntax is already very concise.
Conformance is used in order to find out whether some expression can be used in a certain situation. For instance when assigning a value to a variable, the type of the right hand expression needs to conform to the type of the variable.
As Xbase implements the unchanged type system of Java it also fully supports the conformance rules defined in The Java Language Specification.