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javaexceptionkotlin
Nour Eldin Ahmed
Nour Eldin Ahmed

Reputation: 273

Why doesn't Kotlin require try and catch explicitly

For example: 

FileOutputStream("file")

would compile in Kotlin, but in Java it would give a compiler error. Why?

Upvotes: 5

Views: 5143

Answers (2)

Nate Vaughan
Nate Vaughan

Reputation: 3839

Kotlin does away with Java's checked exceptions. Exceptions checked at compile time and declared in method signatures, though familiar to Java developers, are widely considered a failed experiment outside and to some degree inside the Java community.

So Kotlin did away with them, and with some of the boilerplate associated with using resources (like FileOutputStream) with the .use method shorthand for Java 7's try-with-resources.

Upvotes: 4

Ekeko
Ekeko

Reputation: 1979

It can be difficult to answer without letting some opinions interfere. I will just say that Kotlin is aimed at large software projects and give you what the Kotlin team claims regarding checked exceptions (from https://kotlinlang.org/docs/reference/exceptions.html):

Checked Exceptions

Kotlin does not have checked exceptions. There are many reasons for this, but we will provide a simple example.

The following is an example interface of the JDK implemented by StringBuilder class:

Appendable append(CharSequence csq) throws IOException; What does this signature say? It says that every time I append a string to something (a StringBuilder, some kind of a log, a console, etc.) I have to catch those IOExceptions. Why? Because it might be performing IO (Writer also implements Appendable)… So it results into this kind of code all over the place:

try {
    log.append(message)
}
catch (IOException e) {
    // Must be safe
}

And this is no good, see Effective Java, Item 65: Don't ignore exceptions.

Bruce Eckel says in Does Java need Checked Exceptions?:

Examination of small programs leads to the conclusion that requiring exception specifications could both enhance developer productivity and enhance code quality, but experience with large software projects suggests a different result – decreased productivity and little or no increase in code quality.

Other citations of this sort:

Java's checked exceptions were a mistake (Rod Waldhoff)

The Trouble with Checked Exceptions (Anders Hejlsberg)

Upvotes: 3

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