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Diffstat (limited to 'book/src/main/scalatex/indepth/JavaAPIs.scalatex')
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diff --git a/book/src/main/scalatex/indepth/JavaAPIs.scalatex b/book/src/main/scalatex/indepth/JavaAPIs.scalatex new file mode 100644 index 0000000..51ac71f --- /dev/null +++ b/book/src/main/scalatex/indepth/JavaAPIs.scalatex @@ -0,0 +1,46 @@ +@import book.BookData._ + +@p + Below is a list of classes from the Java Standard Library that are available from Scala.js. In general, much of @hl.scala{java.lang}, and parts of @hl.scala{java.io}, @hl.scala{java.util} and @hl.scala{java.net} have been ported over. This means that all these classes are available for use in Scala.js applications despite being part of the Java standard library. +@p + There are many reasons you may want to port a Java class to Scala.js: you want to use it directly, you may be trying to port a library which uses it. In general, we haven't been porting things "for fun", and obscure classes like @hl.scala{org.omg.corba} will likely never be ported: we've been porting things as the need arises in order to support libraries (e.g. @lnk("Scala.Rx", "https://github.com/lihaoyi/scala.rx") that need them. + +@sect{Available Java APIs} + + @ul + @for(data <- BookData.javaAPIs) + @li + @a(data._1, href:=data._2) + +@sect{Porting Java APIs} + @p + The process for making Java library classes available in Scala.js is relatively straightforward: + @ul + @li + Find a class that you want to use in Scala.js, but is not implemented. + @li + Write a clean-room implementation in Scala, without looking at the source code of @lnk("OpenJDK", "http://openjdk.java.net/"). This is due to legal-software-license incompatibility between OpenJDK and Scala.js. Reading the docs or specification are fine, as is looking at the source of alternate implementations such as @lnk("Harmony", "http://harmony.apache.org/") + @li + Submit a pull-request to the @lnk("Scala.js repository", "https://github.com/scala-js/scala-js"), including your implementation, together with tests. See the @lnk("existing tests", "https://github.com/scala-js/scala-js/tree/master/test-suite/src/test/scala/org/scalajs/testsuite/javalib") in the repository if you need examples of how to write your own. + + @p + In general, this is a simple process, for "pure-Java" classes which do not use any special JVM/Java-specific APIs. However, this will not be possible for classes which do! This means that classes that make use of Java-specific things like: + + @ul + @li + Threads + @li + Filesystem APIs + @li + Network APIs + @li + @hl.scala{sun.misc.Unsafe} + + @p + And other similar APIs will either need to be rewritten to not-use them. For example, @hl.scala{AtomicXXXs} can be written without threading/unsafe APIs because Javascript is single-threaded, making the implementation for e.g. an @hl.scala{AtomicBoolean} pretty trivial: + + @hl.ref(cloneRoot/"scala-js"/'javalib/'src/'main/'scala/'java/'util/'concurrent/'atomic/"AtomicBoolean.scala") + + @p + Others can't be ported at all (e.g. @code{java.io.File}) simply because the API capabilities they provide (blocking reads & writes to files) do not exist in the Javascript runtime. + |