Java 8 Lambda Expressions - Revision history

Gregab: Added advanced.

2018-12-07T17:54:39Z

Added advanced.

Gregab: Shuffled bits around.

2018-12-07T13:51:13Z

Shuffled bits around.

Gregab: Added assumptions and intro.

2018-12-07T13:13:55Z

Added assumptions and intro.

Gregab: Stub example. To be finished.

2018-11-21T12:21:39Z

Stub example. To be finished.

New page

= Introduction =

TBD.

= Examples =

== Parameterless Void Method ==

Consider interface <code>Runnable</code>, which requires you to supply a <code>void run()</code> method in an implementation:

public interface Runnable {
void run();
}

This is a common way of starting <code>Thread</code>s:

public void startThread() {
Runnable r = new Runnable() {
public void run() {
new JobRunner().doJob();
}
};
Thread t = new Thread(r);
t.start();
}

Instead of going the long way, an anonymous inner class can be used in constructor parameter:

public void startThread() {
Thread t = new Thread(new Runnable() {
public void run() {
new JobRunner().doJob();
}
});
t.start();
}

One can now use a lambda expression to reduce the amount of boilerplate:

public class MyCode {
// ...
public void startThread() {
Runnable r = () -> { new JobRunner().doJob(); };
Thread t = new Thread(r);
t.start();
}
// ...
}

Or even?

public class MyCode {
// ...
public void startThread() {
Thread t = new Thread(() -> { new JobRunner().doJob(); });
t.start();
}
// ...
}

@@ Line 27: / Line 27: @@
 The above two excerpts define when lambda expressions can be used, and define the rules for deriving the signature of that expression from the function that the interface proposes.
-== Building on Foundations ==
+== Building on Foundation ==
 TROLOLO.
 = Examples =

@@ Line 1: / Line 1: @@
 = Introduction =
 Java 8 introduced ''functional interfaces'', a special type of an interface which only has one abstract method.
-The key excerpt from the ''[https://www.jcp.org/en/jsr/detail?id=337 Java 8 Language Specification]'' related to the subject of this article seems to be:
+The key excerpts from the ''[https://www.jcp.org/en/jsr/detail?id=337 Java 8 Language Specification]'' that Lambda Expressions build upon are:
 <blockquote>In addition to the usual process of creating an interface instance by declaring and instantiating a class (§15.9), instances of functional interfaces can be created with method reference expressions and lambda expressions (§15.13, §15.27).</blockquote>
-== What I assume ==
+and
-To best focus on the content of this article, I assume the reader is:
+== Building on Foundations ==
-* fluent in Java language (according to v7 language specification)
+TROLOLO.
 = Examples =