What are the differences in features and syntax between Java and Kotlin?

Kotlin and Java both run on the JVM but have several differences in syntax and capabilities:

• Shorter and more expressive syntax in Kotlin: for example, declaring variables with val and var, and writing functions without classes.
• Null safety is built into Kotlin, reducing the number of NullPointerExceptions. In Java, this is achieved through annotations and checks.
• Functional features: Kotlin supports lambda expressions, extension functions, properties, data classes, sealed classes, which simplify the code.
• No checked exceptions in Kotlin, unlike Java.
• Interoperability: Kotlin is fully compatible with Java, allowing calling Java code from Kotlin and vice versa.

Example in Kotlin:

fun greet(name: String?): String {
    return "Hello, ${name ?: "Guest"}!"
}

The equivalent in Java would be longer due to null checks and string concatenation.