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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 2

The Example 2 class is another anonymous class but this time it closes over the server variable. It's an old style closure:

public class Example2 {
    // anonymous class (closure)
    void example() throws InterruptedException {
        Server server = new HttpServer();
        waitFor(new Condition() {
            @Override
            public Boolean isSatisfied() {
                return !server.isRunning();
            }
        });
    }
}

The bytecode is similar to the previous except that an instance of the Server class is newed up (at line 3.) and it's constructor called at line 5. The instance of the anonymous class $1 is still constructed with invokespecial (at line 11.) but this time it takes the instance of Server as an argument as well as the instance of the calling class.

To close over the server variable, it's passed directly into the anonymous class:

void example() throws java.lang.InterruptedException;
    Code:
       0: new #2 // class Server$HttpServer...
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