#Java

As most Java programmers know, Java generics are erased at compile-time. This has trade-offs, but the two main reasons for this are:

• Compatibility - Java 1.4 and earlier dealt exclusively in raw types at the VM level. Generics were able to compile without introducing significant new typing to the bytecode and classfile format spec, and having to deal with older classes generated without that typing.
• Simplicity - By erasing to raw types, the JVM doesn’t have to understand specialization; something that has its own complexities and downsides. For example, specialized types are much more challenging to optimize with a just-in-time compiler.

However, knowing the type parameters used at runtime can have real value, and it’s something Java simply doesn’t offer. Kotlin would like to help in this area, but there are many challenges in doing so.

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One of Kotlin’s strengths is that generally speaking, the code you might write in Java is generally more compact in Kotlin without losing any of the readability, functionality, or performance.

An odd case where that doesn’t prove to be true is declaring loggers as Java developers.

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This year at JVMLS, Brian Goetz talked about Pattern Matching on the JVM and how it might be modeled. In particular he spoke about:

• How Scala does it
• How C# does it
• How Java might do it
• How Java could do it with amortized constant-time Matching

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Today’s Kotlin library article is about the kotlin.concurrent package, and everything that adds to the platform.

Java’s concurrency package is already quite sophisticated, and rather than re-invent so many extremely delicate abstractions, the Kotlin authors focused on making the libraries better suited to the language by decorating and shortening various features.

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This is the second article in a series around Kotlin standard library additions. This article is all about the Kotlin comparator factory functions.

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This is the first in a series of articles that will quickly go over some of the more interesting bits of the Kotlin standard libraries for Java. Today’s run-through is about some of the more interesting affordances for I/O based programming.

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Java 8 now has some functional concepts. How functional can it really get, though?[Read More]

Java 8 introduces lambdas, but it also introduces method references which are a very handy syntax for producing lambdas off of objects and classes. I walk through the various types here.[Read More]

Java supports throwing exceptions of a generic type, but it is rarely a useful trick. With Java 8, that is changing.[Read More]

Setting up bi-directional relationships in Google App Engine efficiently can be tricky. I show you an efficient approach here.[Read More]