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Learning Java Lambdas

You're reading from   Learning Java Lambdas An in-depth look at one of the most important features of modern Java

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Product type Paperback
Published in Mar 2017
Publisher
ISBN-13 9781787282087
Length 114 pages
Edition 1st Edition
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Author (1):
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Toby Weston Toby Weston
Author Profile Icon Toby Weston
Toby Weston
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Toc

Example 4

The Example 4 class is another lambda but this time it takes an instance of Server as an argument. It's equivalent in functionality to example 2 but it doesn't close over the variable; it's not a closure.

public class Example4 {
    // lambda with arguments
    void example() throws InterruptedException {
        waitFor(new HttpServer(), (server) -> server.isRunning());
    }
}

Just like example 2, the bytecode has to create the instance of server but this time, the invokedynamic opcode references the test method of type Predicate. If we were to follow the reference (#4) to the boostrap methods table, we would see the actual lambda requires an argument of type HttpServer and returns a Z which is a primitive boolean.

void example() throws java.lang.InterruptedException;
    descriptor: ()V
    flags:
    Code:
      stack=2, locals=1, args_size=1
         0: new #2 // class Server$HttpServer
         3: dup
         4: invokespecial #3 // Method Server$HttpServer...
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