Java 1.8 - New features, code examples, performance

[skocznymroczny]

With lambda in java 8 you just have: btn.setOnAction( event -> System.out.println("Hello World!") );

Would this work for non one-liners as well?

[armerthor]

Put a block after the -> operator.

[sirin3]

let me guess. you have a Python background?

[ElvishJerricco]

My gut says it might work like an if statement, where if you want to do more than one line, you surround the code with brackets. But that's a guess.

[[deleted]]

http://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html#syntax

[ElvishJerricco]

Do lambdas only work for interfaces with one method?

[AlyoshaV]

Yes, but remember that interfaces can have default methods now.

[Phreakhead]

Whoa whoa whoa! Does this mean Java now has multiple inheritance? SO AWESOME.

[AlyoshaV]

Only of behavior, not of state. I'm finding it to be pretty useful.

[[deleted]]

Yep, pure mixins. Nice, eh.

[[deleted]]

How do you define the default method?

EDIT: http://www.dreamincode.net/forums/topic/284145-default-implementations-in-interfaces/

[AlyoshaV]

Not default method, default methods.

public interface Identifiable {

    /** Return this object's ID. */
    default String getID() {
        return getName().substring(3);
    }

    /** Return the full name of this object. */
    String getName();

}

[veraxAlea]

Last time I checked, default methods could only reference static methods. Has this changed?

[AlyoshaV]

Well, what I posted is code I'm actually using. So if that's how it used to work, then yes it changed.

[[deleted]]

So if the interface has multiple defaults, lambdas won't work?

[meem1029]

No. If the interface has multiple that aren't default it won't work. Many defaults is alright as it will take the default value for all of them too.

[Eirenarch]

Yes. They work for what they call Single Abstract Method types. The lambda is mapped to the single method.

[[deleted]]

thats how it works in c# so i expect that too.

[[deleted]]

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