Explain the concept of safe handling of null in Kotlin and how it is implemented.

In Kotlin, the concept of safe handling of null is implemented through a type system that supports nullable and non-nullable types.

• By default, variables cannot contain null. For example, var a: String = "text" cannot be null.
• To allow null, the type is declared with a ?, for example, var b: String? = null.

To work with nullable types, Kotlin provides:

• Safe call operator ?. — allows calling a method or accessing a property if the object is not null, otherwise returns null.
• Elvis operator ?: — provides a default value if the expression on the left is null.
• Not-null assertion operator !! — forcibly converts a nullable type to a non-nullable one, throwing an exception if the value is null.

Example:

val name: String? = null
println(name?.length) // Outputs null, does not throw an error
println(name?.length ?: 0) // Outputs 0
println(name!!.length) // Throws NullPointerException

Thus, Kotlin helps avoid classic null errors at compile time, making the code more reliable.