{"id":689,"date":"2021-08-27T14:34:52","date_gmt":"2021-08-27T13:34:52","guid":{"rendered":"https:\/\/vukieuanh.com\/?p=689"},"modified":"2021-08-27T14:34:52","modified_gmt":"2021-08-27T13:34:52","slug":"cach-tao-lop-immutable-trong-java","status":"publish","type":"post","link":"https:\/\/vukieuanh.net\/index.php\/2021\/08\/27\/cach-tao-lop-immutable-trong-java\/","title":{"rendered":"C\u00e1ch t\u1ea1o l\u1edbp Immutable trong Java"},"content":{"rendered":"\n

C\u00f3 m\u1ed9t v\u00e0i l\u1edbp b\u1ea5t bi\u1ebfn nh\u01b0 String, Boolean, Byte, Short, Integer, Long, Float, Double, … Hay t\u1ea5t c\u1ea3 nh\u1eefng l\u1edbp Wrapper v\u00e0 l\u1edbp String l\u00e0 b\u1ea5t bi\u1ebfn(immutable). <\/p>\n\n\n\n

\u0110\u1ec3 t\u1ea1o 1 l\u1edbp b\u1ea5t bi\u1ebfn m\u00ecnh \u00e1p d\u1ee5ng c\u00e1c b\u01b0\u1edbc sau nh\u00e9:<\/p>\n\n\n\n

B1: S\u1eed d\u1ee5ng 1 h\u00e0m t\u1ea1o c\u00f3 t\u1ea5t c\u1ea3 c\u00e1c propertive<\/p>\n\n\n\n

B2: \u0110\u00e1nh d\u1ea5u t\u1ea5t c\u1ea3 c\u00e1c thu\u1ed9c t\u00ednh, k\u1ec3 c\u1ea3 thu\u1ed9c t\u00ednh tham chi\u1ebfu l\u00e0 private<\/code> v\u00e0 final<\/code><\/p>\n\n\n\n

B3: Kh\u00f4ng \u0111\u1ecbnh ngh\u0129a 1 `setter` n\u00e0o c\u1ea3<\/p>\n\n\n\n

B4: Kh\u00f4ng cho ph\u00e9p s\u1eeda \u0111\u1ed5i ho\u1eb7c truy c\u1eadp tr\u1ef1c ti\u1ebfp c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n\n\n\n

B5: Kh\u00f4ng cho ph\u00e9p ghi \u0111\u00e8 ph\u01b0\u01a1ng th\u1ee9c (1 l\u00e0 \u0111\u1ecbnh ngh\u0129a class \u0111\u1ea5y l\u00e0 final, 2 l\u00e0 t\u1ea5t c\u1ea3 c\u00e1c ph\u01b0\u01a1ng th\u1ee9c l\u00e0 final, c\u00e1c b\u1ea1n mu\u1ed1n l\u00e0m c\u00e1ch n\u00e0o c\u0169ng \u0111\u01b0\u1ee3c)<\/p>\n\n\n\n

Ta x\u00e9t v\u00ed d\u1ee5 sau: <\/p>\n\n\n\n

public class Animal {
    private final List<String> favoriteFoods;
    public Animal(List<String> favoriteFoods) { 
        if(favoriteFoods == null) {
        throw new RuntimeException(\"favoriteFoods is required\"); 
        }
        this.favoriteFoods = new ArrayList<String>(favoriteFoods); 
    }
    public List<String> getFavoriteFoods() { 
        \/\/ MAKES CLASS MUTABLE! 
        return favoriteFoods;
    }
}<\/pre>\n\n\n\n
Trong v\u00ed tr\u00ean sau b\u01b0\u1edbc 4 kh\u00f4ng \u0111\u01b0\u1ee3c \u0111\u1ea3m b\u1ea3o v\u00ec ph\u01b0\u01a1ng th\u1ee9c getFavoriteFoods() tr\u1ea3 v\u1ec1 bi\u1ebfn \u0111\u1ed1i t\u01b0\u1ee3ng favoriteFoods c\u1ee7a Animal, th\u1eb1ng n\u00e0o m\u00e0 get ra \u0111\u01b0\u1ee3c c\u00e1i n\u00e0y th\u00ec n\u00f3 ch\u1eb3ng s\u1eeda \u0111c \u00e0, n\u00ean v\u1edbi c\u00e1c bi\u1ebfn tham chi\u1ebfu n\u00e0y, c\u00e1c \u00f4ng clone ra 1 \u0111\u1ed1i t\u01b0\u1ee3ng kh\u00e1c m\u00e0 tr\u1ea3 v\u1ec1 nh\u00e9. Th\u00e2n!<\/p>\n\n\n\n
Ti\u1ebfp t\u1ee5c x\u00e9t ti\u1ebfp v\u00ed d\u1ee5 n\u1eefa:<\/p>\n\n\n\n
public final class Animal {
    private final String species;
    private final int age;
    private final List<String> favoriteFoods;
    public Animal(String species, int age, List<String> favoriteFoods) { this.species = species;
        this.age = age;
        if(favoriteFoods == null) {
            throw new RuntimeException(\"favoriteFoods is required\"); }
        this.favoriteFoods = new ArrayList<String>(favoriteFoods); 
    }
    public String getSpecies() { return species;
    }
    public int getAge() { return age;
    }
    public int getFavoriteFoodsCount() { return favoriteFoods.size();
    }
    public String getFavoriteFood(int index) { return favoriteFoods.get(index);
    } 
}<\/pre>\n\n\n\n
Trong v\u00ed d\u1ee5 tr\u00ean, c\u00e1c b\u1ea1n cmt xem \u0111\u1ee7 5 ti\u00eau ch\u00ed ch\u01b0a nh\u00e9. Th\u00e2n, <\/p>\n\n\n\n
Mong \u0111\u1ee3i cmt t\u1eeb c\u00e1c b\u1ea1n.<\/p>\n","protected":false},"excerpt":{"rendered":"
C\u00f3 m\u1ed9t v\u00e0i l\u1edbp b\u1ea5t bi\u1ebfn nh\u01b0 String, Boolean, Byte, Short, Integer, Long, Float, Double, … Hay t\u1ea5t c\u1ea3 nh\u1eefng l\u1edbp Wrapper v\u00e0 l\u1edbp String l\u00e0 b\u1ea5t bi\u1ebfn(immutable). \u0110\u1ec3 t\u1ea1o 1 l\u1edbp b\u1ea5t bi\u1ebfn m\u00ecnh \u00e1p d\u1ee5ng c\u00e1c b\u01b0\u1edbc sau nh\u00e9: B1: S\u1eed d\u1ee5ng 1 h\u00e0m t\u1ea1o c\u00f3 t\u1ea5t c\u1ea3 c\u00e1c propertive B2: \u0110\u00e1nh d\u1ea5u […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-689","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/posts\/689","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/comments?post=689"}],"version-history":[{"count":1,"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/posts\/689\/revisions"}],"predecessor-version":[{"id":690,"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/posts\/689\/revisions\/690"}],"wp:attachment":[{"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/media?parent=689"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/categories?post=689"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vukieuanh.net\/index.php\/wp-json\/wp\/v2\/tags?post=689"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}