Java: The Next Generation

A few weeks ago, plans for the next version of Java were released. It will be split into two different versions in order to more quickly get a new version out the door. Two key features that were originally slated to be released in Java 7, will be pushed back to Java 8.

One of these features is called Lambda, which adds closures to Java. From what I understand, a closure is like a function that can be assigned to a variable. This means that the closure can be passed as an argument to another function, and then called inside of the function's body. If the closure is declared inside of another function, it has access to the parent function's local variables. Many languages support this. Here is an example of how closures can be used in Javascript (taken from Wikipedia):

// Return a list of all books with at least 'threshold' copies sold.
function bestSellingBooks(threshold) {
  return bookList.filter(
      function (book) { return book.sales >= threshold; }
  );
}

The function filters the bookList array, returning only the books that have sold a mininum number of copies. It does this by passing a closure into the filter() method, which gets executed on every book in the array. If the closure returns true for a particular book, then that book is filtered out.

The other major feature that was pushed back to Java 8 is called Jigsaw. The goal of Jigsaw is to break the JDK into separate modules. This would help applications boot up more quickly. It also would help in situations where a JRE is packaged with the application. This JRE could be reduced in size by only including the modules that the application needs.

Java 7 is slated for release in mid-2011 and Java 8 is to be released sometime in 2012.