{"id":13855,"date":"2022-10-07T13:04:19","date_gmt":"2022-10-07T11:04:19","guid":{"rendered":"https:\/\/www.espai.es\/blog\/?p=13855"},"modified":"2022-10-10T10:59:41","modified_gmt":"2022-10-10T08:59:41","slug":"java-lambdas","status":"publish","type":"post","link":"https:\/\/www.espai.es\/blog\/2022\/10\/java-lambdas\/","title":{"rendered":"Java Lambdas"},"content":{"rendered":"

Hola a todos y bienvenidos a un nuevo art\u00edculo del blog. Hoy vamos a hablar de Java Lambdas<\/strong>, que son una novedad (bueno en Java 8, ejem) para abreviar nuestro c\u00f3digo.<\/span><\/p>\n

 <\/p>\n

\"Java<\/a>

Esta letra del alfabeto griego representa \u201cLambda\u201d. Y de paso, cierto videojuego\u2026<\/p><\/div>\n

 <\/p>\n

\u00cdndice de contenidos<\/span><\/h2>\n
    \n
  1. Clases an\u00f3nimas<\/span><\/a><\/li>\n
  2. Lambdas<\/span><\/a><\/li>\n
  3. \u00bfCu\u00e1ndo usar cada uno?<\/span><\/a><\/li>\n<\/ol>\n

     <\/p>\n

    Clases an\u00f3nimas<\/span><\/h2>\n

     <\/p>\n

    \u00bfNo iba de Lambdas esto? Pues s\u00ed\u2026 Precisamente una expresi\u00f3n lambda es \u00abcasi\u00bb la abreviatura de una clase an\u00f3nima. Seguramente te suena este c\u00f3digo<\/span><\/p>\n

     <\/p>\n

    \"Java<\/p>\n

     <\/p>\n

    El fragmento marcado en rojo representa una clase an\u00f3nima. Como tal, necesita que implementemos la interfaz \u201cActionListener\u201d, con todo el c\u00f3digo que eso implica. Abrir y cerrar la clase con las llaves, definir la funci\u00f3n con sus par\u00e1metros, definir el tipo de dato de cada par\u00e1metro (en este caso solo 1, ActionEvent)<\/span><\/p>\n

    Vamos, que para un simple mensaje \u201chas hecho click\u201d necesitamos 6 o 7 l\u00edneas de c\u00f3digo, con varias llaves entre medio y el correspondiente l\u00edo. Imag\u00ednate si hay 5 botones, el c\u00f3digo se multiplica.<\/span><\/p>\n

     <\/p>\n

    Por cierto, el editor utilizado es Eclipse<\/a>. Puedes descargarlo aqu\u00ed<\/a>.<\/p>\n

     <\/p>\n

    Lambdas<\/h2>\n

    \u00bfC\u00f3mo \u00abactualizamos\u00bb una clase an\u00f3nima para que sea un Lambda? As\u00ed:<\/p>\n

     <\/p>\n

    \"Java<\/p>\n

     <\/p>\n

    Si comparamos este c\u00f3digo con la clase an\u00f3nima anterior, ha desaparecido casi todo. S\u00f3lo queda esto:<\/span><\/p>\n

     <\/p>\n

    \"Java<\/p>\n

     <\/p>\n

    As\u00ed que \u00e9ste fragmento:<\/span><\/p>\n

    (e)<\/b><\/p>\n

    reemplaza a\u00a0<\/span><\/p>\n

     <\/p>\n

    new ActionListener() {<\/b><\/p>\n

    @Override<\/b><\/p>\n

    public void actionPerformed(ActionEvent e) {<\/b><\/p>\n

     <\/p>\n

    \u00bfNo est\u00e1 mal, verdad? Aqu\u00ed Java \u201cdeduce\u201d todo lo que falta, es decir el tipo de clase (ActionListener), el nombre de la funci\u00f3n (actionPerformed), el tipo del par\u00e1metro que recibe (ActionEvent) y se queda s\u00f3lo con el nombre del par\u00e1metro (en este caso, <\/span>e<\/b>)<\/span><\/p>\n

     <\/p>\n

    Y lo puede deducir, porque sabe que addActionListener NECESITA RECIBIR un <\/span>ActionListener<\/b>.<\/span><\/p>\n

     <\/p>\n

    Como ActionListener <\/span>s\u00f3lo define una funci\u00f3n<\/b>,\u00a0 tambi\u00e9n sabe que queremos implementar actionPerformed. Y sabiendo eso, tambi\u00e9n sabe que el par\u00e1metro que pasemos a actionPerformed es de tipo ActionEvent.<\/span><\/p>\n

     <\/p>\n

    Es decir que toda esa informaci\u00f3n \u201crepetida\u201d que estamos pasando al crear una clase an\u00f3nima, desaparece al escribir un lambda.<\/span><\/p>\n

     <\/p>\n

    \"meme\"

    cortes\u00eda de makeameme.org<\/p><\/div>\n

     <\/p>\n

    \u00bfCu\u00e1ndo usar cada uno?<\/span><\/h2>\n

     <\/p>\n

    De entrada es preferible usar Lambdas. Ya sabes: \u201cLo bueno si breve, 2 veces bueno\u201d<\/span><\/p>\n

     <\/p>\n

    En cambio, si debes implementar 2 o m\u00e1s funciones abstractas, <\/span>no podr\u00e1s usarlos<\/b>.<\/span><\/p>\n

     <\/p>\n

    \u00bfPorqu\u00e9 no puedo usar Java Lambdas para implementar varias funciones?<\/strong><\/p>\n

     <\/p>\n

    Porque al no especificar en el lambda el nombre de la funci\u00f3n que usas, Java no sabr\u00eda a cu\u00e1l te refieres. Por eso est\u00e1n limitados a interfaces con 1 sola funci\u00f3n.<\/span><\/p>\n

    \"meme\"

    Expresi\u00f3n Lambda cuando debe implementar 2 funciones<\/p><\/div>\n

     <\/p>\n

    En este caso vienen al rescate las <\/span>clases an\u00f3nimas<\/b>, que no tienen esta limitaci\u00f3n. Puedes implementar tantas funciones como quieras, e incluso usar clases abstractas en lugar de Interfaces.<\/span><\/p>\n

     <\/p>\n

    Como ves el contenido es un poco espeso, pero en siguientes art\u00edculos profundizaremos en el tema y veremos otras aplicaciones interesantes de las Java Lambdas.<\/span><\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

    Hasta el pr\u00f3ximo art\u00edculo \ud83d\ude09<\/p>\n","protected":false},"excerpt":{"rendered":"

    Hola a todos y bienvenidos a un nuevo art\u00edculo del blog. Hoy vamos a hablar de Java Lambdas, que son una novedad (bueno en Java 8, ejem) para abreviar nuestro c\u00f3digo.     \u00cdndice de contenidos Clases an\u00f3nimas Lambdas \u00bfCu\u00e1ndo usar cada uno?   Clases…<\/p>\n","protected":false},"author":3,"featured_media":13871,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_ef_editorial_meta_date_first-draft-date":"","_ef_editorial_meta_paragraph_assignment":"","_ef_editorial_meta_checkbox_needs-photo":"","_ef_editorial_meta_number_word-count":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[5],"tags":[220,89],"class_list":["post-13855","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-programacion","tag-java","tag-programacion-2"],"yoast_head":"\nJava Lambdas - 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