Java - Lambdas

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Lambdas

Syntax

 (String first, String second) -> Integer.compare(first.length(), second.length())

Functional Interfaces

Declaration

Runnable has a functional interface wich has exactly one abstract method

 Runnable runner = () -> { ...; System.out.println(this.toString()); ... };

(String first, String second) -> {
   if (first.length() < second.length()) return -1;
   else if (first.length() > second.length()) return 1;
   else return 0;
}

Use

Arrays.sort(strings, String::compareToIgnoreCase)

Use

Use Functional Interfaces https://docs.oracle.com/javase/8/docs/api/java/lang/FunctionalInterface.html They have only one method

Questions & Answers

concrete methods interface methode default implementee = interface fonctionnelle

  • if a class implements two interfaces with the same name method: multiplicatedefaulterror

je ne peux utiliser que les variables finales dans une lambda expression lambda n'est pas thread safe

Loops

INTERNAL: nouveau foreach ==> je ne veux pas savoir ce ton implementation: fais le avec la lambda que je te donne EXTERNAL: ancien foreach, a BANNIR