Comparison to Java Programming Language

• Null references are controlled by the type system.
• Arrays in Kotlin are invariant
• Kotlin has proper , as opposed to Java’s SAM-conversions
• Use-site variance without wildcards
• Kotlin does not have checked

• Primitive types that are not classes - The byte-code uses primitives where possible, but they are not explicitly available.
• - replaced with companion objects, , extension functions, or .
• Wildcard-types - replaced with and type projections.
• - replaced with if expression.

• + Inline functions = performant custom control structures
• Null-safety
• String templates
• First-class delegation
• Singletons
• Range expressions
• Companion objects
• Coroutines