{"id":850,"date":"2026-03-17T08:41:36","date_gmt":"2026-03-17T08:41:36","guid":{"rendered":"https:\/\/www.viz-tools.com\/vi\/the-complete-guide-to-uml-class-diagrams\/"},"modified":"2026-03-17T08:41:36","modified_gmt":"2026-03-17T08:41:36","slug":"the-complete-guide-to-uml-class-diagrams","status":"publish","type":"post","link":"https:\/\/www.viz-tools.com\/vi\/the-complete-guide-to-uml-class-diagrams\/","title":{"rendered":"H\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n v\u1ec1 S\u01a1 \u0111\u1ed3 L\u1edbp UML"},"content":{"rendered":"

Gi\u1edbi thi\u1ec7u<\/span><\/h1>\n
Trong th\u1ebf gi\u1edbi k\u1ef9 thu\u1eadt ph\u1ea7n m\u1ec1m v\u00e0 thi\u1ebft k\u1ebf h\u1ec7 th\u1ed1ng, s\u1ef1 r\u00f5 r\u00e0ng v\u00e0 giao ti\u1ebfp l\u00e0 \u0111i\u1ec1u t\u1ed1i quan tr\u1ecdng. D\u00f9 b\u1ea1n \u0111ang thi\u1ebft k\u1ebf m\u1ed9t \u1ee9ng d\u1ee5ng m\u1edbi, t\u00e0i li\u1ec7u h\u00f3a m\u1ed9t h\u1ec7 th\u1ed1ng hi\u1ec7n c\u00f3 hay h\u1ee3p t\u00e1c v\u1edbi m\u1ed9t nh\u00f3m \u0111a ch\u1ee9c n\u0103ng, vi\u1ec7c c\u00f3 m\u1ed9t ng\u00f4n ng\u1eef h\u00ecnh \u1ea3nh chung l\u00e0 \u0111i\u1ec1u c\u1ea7n thi\u1ebft. \u0110\u00e2y ch\u00ednh l\u00e0 l\u00fac <\/span>S\u01a1 \u0111\u1ed3 L\u1edbp UML<\/span><\/strong> ph\u00e1t huy vai tr\u00f2.<\/span><\/div>\n
<\/div>\n
L\u00e0 m\u1ed9t trong nh\u1eefng s\u01a1 \u0111\u1ed3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng ph\u1ed5 bi\u1ebfn nh\u1ea5t trong ti\u00eau chu\u1ea9n Ng\u00f4n ng\u1eef M\u00f4 h\u00ecnh h\u00f3a \u0110\u01a1n nh\u1ea5t (UML), s\u01a1 \u0111\u1ed3 l\u1edbp cung c\u1ea5p m\u1ed9t c\u00e1ch th\u1ee9c m\u1ea1nh m\u1ebd v\u00e0 chu\u1ea9n h\u00f3a \u0111\u1ec3 bi\u1ec3u di\u1ec5n c\u1ea5u tr\u00fac t\u0129nh c\u1ee7a m\u1ed9t h\u1ec7 th\u1ed1ng h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng. Ch\u00fang cho ph\u00e9p c\u00e1c nh\u00e0 ph\u00e1t tri\u1ec3n, ki\u1ebfn tr\u00fac s\u01b0 v\u00e0 c\u00e1c b\u00ean li\u00ean quan h\u00ecnh dung \u0111\u01b0\u1ee3c c\u00e1c l\u1edbp, thu\u1ed9c t\u00ednh, thao t\u00e1c v\u00e0 c\u00e1c m\u1ed1i quan h\u1ec7 k\u1ebft n\u1ed1i ch\u00fang l\u1ea1i v\u1edbi nhau\u2014tr\u01b0\u1edbc khi m\u1ed9t d\u00f2ng m\u00e3 n\u00e0o \u0111\u01b0\u1ee3c vi\u1ebft ra.<\/span><\/div>\n
<\/div>\n
H\u01b0\u1edbng d\u1eabn to\u00e0n di\u1ec7n n\u00e0y s\u1ebd d\u1eabn b\u1ea1n qua m\u1ecdi th\u1ee9 b\u1ea1n c\u1ea7n bi\u1ebft v\u1ec1 s\u01a1 \u0111\u1ed3 l\u1edbp UML: t\u1eeb c\u00e1c k\u00fd hi\u1ec7u c\u1ed1t l\u00f5i v\u00e0 lo\u1ea1i m\u1ed1i quan h\u1ec7 \u0111\u1ebfn c\u00e1c b\u01b0\u1edbc v\u1ebd th\u1ef1c t\u1ebf v\u00e0 c\u00e1c v\u00ed d\u1ee5 trong th\u1ef1c t\u1ebf. D\u00f9 b\u1ea1n l\u00e0 sinh vi\u00ean h\u1ecdc c\u00e1c nguy\u00ean t\u1eafc thi\u1ebft k\u1ebf ph\u1ea7n m\u1ec1m, nh\u00e0 ph\u00e1t tri\u1ec3n \u0111ang ho\u00e0n thi\u1ec7n k\u1ef9 n\u0103ng m\u00f4 h\u00ecnh h\u00f3a, hay qu\u1ea3n l\u00fd s\u1ea3n ph\u1ea9m mu\u1ed1n hi\u1ec3u r\u00f5 h\u01a1n v\u1ec1 ki\u1ebfn tr\u00fac k\u1ef9 thu\u1eadt, h\u01b0\u1edbng d\u1eabn n\u00e0y s\u1ebd trang b\u1ecb cho b\u1ea1n ki\u1ebfn th\u1ee9c \u0111\u1ec3 t\u1ea1o ra c\u00e1c s\u01a1 \u0111\u1ed3 l\u1edbp r\u00f5 r\u00e0ng, hi\u1ec7u qu\u1ea3 v\u00e0 d\u1ec5 b\u1ea3o tr\u00ec.<\/span><\/div>\n
<\/div>\n
H\u00e3y c\u00f9ng b\u1eaft tay v\u00e0o v\u00e0 th\u00e0nh th\u1ea1o ngh\u1ec7 thu\u1eadt m\u00f4 h\u00ecnh h\u00f3a h\u1ec7 th\u1ed1ng b\u1eb1ng s\u01a1 \u0111\u1ed3 l\u1edbp UML.<\/span><\/div>\n
<\/div>\n

S\u01a1 \u0111\u1ed3 l\u1edbp trong UML l\u00e0 g\u00ec?<\/h2>\n

S\u01a1 \u0111\u1ed3 l\u1edbp m\u00f4 t\u1ea3 c\u1ea5u tr\u00fac c\u1ee7a m\u1ed9t h\u1ec7 th\u1ed1ng h\u01b0\u1edbng \u0111\u1ed1i t\u01b0\u1ee3ng b\u1eb1ng c\u00e1ch hi\u1ec3n th\u1ecb c\u00e1c l\u1edbp trong h\u1ec7 th\u1ed1ng \u0111\u00f3 v\u00e0 c\u00e1c m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00e1c l\u1edbp. S\u01a1 \u0111\u1ed3 l\u1edbp c\u0169ng hi\u1ec3n th\u1ecb c\u00e1c r\u00e0ng bu\u1ed9c v\u00e0 thu\u1ed9c t\u00ednh c\u1ee7a c\u00e1c l\u1edbp.<\/p>\n

\"Class<\/p>\n

\n

\ud83d\udca1\u00a0Th\u1eed ngay!<\/strong>\u0110ang t\u00ecm ki\u1ebfm m\u1ed9t c\u00f4ng c\u1ee5 s\u01a1 \u0111\u1ed3 l\u1edbp tr\u1ef1c tuy\u1ebfn? Ch\u1ec9 c\u1ea7n nh\u1ea5p v\u00e0o n\u00fat V\u1ebd b\u00ean d\u01b0\u1edbi \u0111\u1ec3 t\u1ea1o s\u01a1 \u0111\u1ed3 l\u1edbp c\u1ee7a b\u1ea1n tr\u1ef1c tuy\u1ebfn. Visual Paradigm Online l\u00e0 mi\u1ec5n ph\u00ed* v\u00e0 d\u1ec5 s\u1eed d\u1ee5ng. B\u1ea1n c\u0169ng c\u00f3 th\u1ec3 tham kh\u1ea3o h\u01b0\u1edbng d\u1eabn s\u01a1 \u0111\u1ed3 l\u1edbp n\u00e0y \u0111\u1ec3 h\u1ecdc v\u1ec1 s\u01a1 \u0111\u1ed3 l\u1edbp tr\u01b0\u1edbc khi b\u1eaft \u0111\u1ea7u.<\/p>\n

V\u1ebd ngay<\/a><\/p>\n<\/blockquote>\n\n

C\u00e1c k\u00fd hi\u1ec7u s\u01a1 \u0111\u1ed3 l\u1edbp<\/h2>\n

L\u1edbp<\/h3>\n

Bi\u1ec3u di\u1ec5n UML c\u1ee7a m\u1ed9t l\u1edbp l\u00e0 m\u1ed9t h\u00ecnh ch\u1eef nh\u1eadt ch\u1ee9a ba ng\u0103n x\u1ebfp \u0111\u01b0\u1ee3c x\u1ebfp d\u1ecdc theo nhau, nh\u01b0 \u0111\u01b0\u1ee3c hi\u1ec3n th\u1ecb trong H\u00ecnh:<\/p>\n

\"UML<\/p>\n

Thu\u1ed9c t\u00ednh<\/h3>\n

Ph\u1ea7n thu\u1ed9c t\u00ednh c\u1ee7a m\u1ed9t l\u1edbp li\u1ec7t k\u00ea t\u1eebng thu\u1ed9c t\u00ednh c\u1ee7a l\u1edbp \u0111\u00f3 tr\u00ean m\u1ed9t d\u00f2ng ri\u00eang bi\u1ec7t. Ph\u1ea7n thu\u1ed9c t\u00ednh l\u00e0 t\u00f9y ch\u1ecdn, nh\u01b0ng khi \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng th\u00ec s\u1ebd ch\u1ee9a t\u1eebng thu\u1ed9c t\u00ednh c\u1ee7a l\u1edbp \u0111\u01b0\u1ee3c hi\u1ec3n th\u1ecb theo \u0111\u1ecbnh d\u1ea1ng danh s\u00e1ch. D\u00f2ng n\u00e0y s\u1eed d\u1ee5ng \u0111\u1ecbnh d\u1ea1ng sau:<\/p>\n

t\u00ean : ki\u1ec3u thu\u1ed9c t\u00ednh\r\n<\/code><\/pre>\n
V\u00ed d\u1ee5:<\/strong>\u00a0cardNumber : S\u1ed1 nguy\u00ean<\/code><\/p>\n
Thao t\u00e1c<\/h3>\n
C\u00e1c thao t\u00e1c \u0111\u01b0\u1ee3c ghi ch\u00fa trong ng\u0103n d\u01b0\u1edbi c\u00f9ng c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt s\u01a1 \u0111\u1ed3 l\u1edbp, c\u0169ng l\u00e0 t\u00f9y ch\u1ecdn. T\u01b0\u01a1ng t\u1ef1 nh\u01b0 thu\u1ed9c t\u00ednh, c\u00e1c thao t\u00e1c c\u1ee7a m\u1ed9t l\u1edbp \u0111\u01b0\u1ee3c hi\u1ec3n th\u1ecb theo \u0111\u1ecbnh d\u1ea1ng danh s\u00e1ch, m\u1ed7i thao t\u00e1c n\u1eb1m tr\u00ean m\u1ed9t d\u00f2ng ri\u00eang bi\u1ec7t. C\u00e1c thao t\u00e1c \u0111\u01b0\u1ee3c ghi ch\u00fa b\u1eb1ng k\u00fd hi\u1ec7u sau:<\/p>\n
t\u00ean (danh s\u00e1ch tham s\u1ed1) : ki\u1ec3u gi\u00e1 tr\u1ecb tr\u1ea3 v\u1ec1\r\n<\/code><\/pre>\n
V\u00ed d\u1ee5:<\/strong>\u00a0calculateTax (Qu\u1ed1c gia, Ti\u1ec3u bang) : Ti\u1ec1n t\u1ec7<\/code><\/p>\n\n
C\u00e1c m\u1ed1i quan h\u1ec7<\/h2>\n
Li\u00ean k\u1ebft<\/h3>\n
M\u1ed9t s\u1ed1 \u0111\u1ed1i t\u01b0\u1ee3ng \u0111\u01b0\u1ee3c t\u1ea1o th\u00e0nh t\u1eeb c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng kh\u00e1c. Li\u00ean k\u1ebft x\u00e1c \u0111\u1ecbnh m\u1ed1i quan h\u1ec7 \u201cc\u00f3-m\u1ed9t\u201d ho\u1eb7c \u201cto\u00e0n-th\u1ec3\/ph\u1ea7n\u201d gi\u1eefa hai l\u1edbp. Trong m\u1ed1i quan h\u1ec7 li\u00ean k\u1ebft, m\u1ed9t \u0111\u1ed1i t\u01b0\u1ee3ng c\u1ee7a l\u1edbp to\u00e0n th\u1ec3 c\u00f3 c\u00e1c \u0111\u1ed1i t\u01b0\u1ee3ng c\u1ee7a l\u1edbp ph\u1ea7n nh\u01b0 d\u1eef li\u1ec7u th\u1ec3 hi\u1ec7n.<\/p>\n
Trong s\u01a1 \u0111\u1ed3 l\u1edbp, m\u1ed1i quan h\u1ec7 li\u00ean k\u1ebft \u0111\u01b0\u1ee3c th\u1ec3 hi\u1ec7n b\u1eb1ng m\u1ed9t \u0111\u01b0\u1eddng li\u1ec1n h\u01b0\u1edbng.<\/p>\n
Li\u00ean k\u1ebft m\u1ed9t chi\u1ec1u<\/h4>\n
Trong m\u1ed9t li\u00ean k\u1ebft m\u1ed9t chi\u1ec1u, hai l\u1edbp c\u00f3 li\u00ean h\u1ec7 v\u1edbi nhau, nh\u01b0ng ch\u1ec9 m\u1ed9t l\u1edbp bi\u1ebft m\u1ed1i quan h\u1ec7 n\u00e0y t\u1ed3n t\u1ea1i. M\u1ed9t li\u00ean k\u1ebft m\u1ed9t chi\u1ec1u \u0111\u01b0\u1ee3c v\u1ebd b\u1eb1ng m\u1ed9t \u0111\u01b0\u1eddng li\u1ec1n c\u00f3 \u0111\u1ea7u m\u0169i t\u00ean h\u1edf h\u01b0\u1edbng v\u1ec1 l\u1edbp \u0111\u01b0\u1ee3c bi\u1ebft \u0111\u1ebfn.<\/p>\n
\"Unidirectional<\/p>\n
Li\u00ean k\u1ebft hai chi\u1ec1u (chu\u1ea9n)<\/h4>\n
M\u1ed9t li\u00ean k\u1ebft l\u00e0 s\u1ef1 k\u1ebft n\u1ed1i gi\u1eefa hai l\u1edbp. C\u00e1c li\u00ean k\u1ebft lu\u00f4n \u0111\u01b0\u1ee3c gi\u1ea3 \u0111\u1ecbnh l\u00e0 hai chi\u1ec1u; \u0111i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 c\u1ea3 hai l\u1edbp \u0111\u1ec1u nh\u1eadn bi\u1ebft v\u1ec1 nhau v\u00e0 m\u1ed1i quan h\u1ec7 gi\u1eefa ch\u00fang, tr\u1eeb khi b\u1ea1n x\u00e1c \u0111\u1ecbnh li\u00ean k\u1ebft l\u00e0 m\u1ed9t lo\u1ea1i kh\u00e1c. M\u1ed9t li\u00ean k\u1ebft hai chi\u1ec1u \u0111\u01b0\u1ee3c bi\u1ec3u th\u1ecb b\u1eb1ng m\u1ed9t \u0111\u01b0\u1eddng li\u1ec1n gi\u1eefa hai l\u1edbp.<\/p>\n
\"Bidirectional<\/p>\n
\u0110a d\u1ea1ng<\/h3>\n
\u0110\u1eb7t k\u00fd hi\u1ec7u \u0111a d\u1ea1ng g\u1ea7n hai \u0111\u1ea7u c\u1ee7a m\u1ed9t li\u00ean k\u1ebft. C\u00e1c k\u00fd hi\u1ec7u n\u00e0y cho bi\u1ebft s\u1ed1 l\u01b0\u1ee3ng th\u1ec3 hi\u1ec7n c\u1ee7a m\u1ed9t l\u1edbp \u0111\u01b0\u1ee3c li\u00ean k\u1ebft v\u1edbi m\u1ed9t th\u1ec3 hi\u1ec7n c\u1ee7a l\u1edbp kia.<\/p>\n
V\u00ed d\u1ee5:<\/strong>M\u1ed9t c\u00f4ng ty s\u1ebd c\u00f3 m\u1ed9t ho\u1eb7c nhi\u1ec1u nh\u00e2n vi\u00ean, nh\u01b0ng m\u1ed7i nh\u00e2n vi\u00ean ch\u1ec9 l\u00e0m vi\u1ec7c cho m\u1ed9t c\u00f4ng ty duy nh\u1ea5t.<\/p>\n
\"Multiplicity<\/p>\n\n\n\n\n\n\n\n\n\n
K\u00fd hi\u1ec7u<\/th>\n\u00dd ngh\u0129a<\/th>\n<\/tr>\n<\/thead>\n
1<\/code><\/td>\nCh\u00ednh x\u00e1c m\u1ed9t<\/td>\n<\/tr>\n
0..1<\/code><\/td>\nKh\u00f4ng ho\u1eb7c m\u1ed9t<\/td>\n<\/tr>\n
*<\/code>ho\u1eb7c0..*<\/code><\/td>\nKh\u00f4ng ho\u1eb7c nhi\u1ec1u<\/td>\n<\/tr>\n
1..*<\/code><\/td>\nM\u1ed9t ho\u1eb7c nhi\u1ec1u<\/td>\n<\/tr>\n
0..3<\/code><\/td>\nKh\u00f4ng \u0111\u1ebfn ba<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
T\u00ednh kh\u1ea3 ki\u1ebfn<\/h3>\n
T\u00ednh kh\u1ea3 ki\u1ebfn \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 ch\u1ec9 ra ai c\u00f3 th\u1ec3 truy c\u1eadp th\u00f4ng tin ch\u1ee9a trong m\u1ed9t l\u1edbp \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u b\u1eb1ng+<\/code>,\u00a0-<\/code>,\u00a0#<\/code>\u00a0v\u00e0\u00a0~<\/code>\u00a0nh\u01b0 \u0111\u01b0\u1ee3c hi\u1ec3n th\u1ecb trong h\u00ecnh:<\/p>\n
\"Visibility<\/p>\n\n\n\n\n\n\n\n\n
K\u00fd hi\u1ec7u<\/th>\n\u0110\u1ed9 kh\u1ea3 d\u1ee5ng<\/th>\nM\u00f4 t\u1ea3<\/th>\n<\/tr>\n<\/thead>\n
+<\/code><\/td>\nC\u00f4ng khai<\/td>\nC\u00f3 th\u1ec3 truy c\u1eadp t\u1eeb b\u1ea5t k\u1ef3 l\u1edbp n\u00e0o kh\u00e1c<\/td>\n<\/tr>\n
-<\/code><\/td>\nRi\u00eang t\u01b0<\/td>\nCh\u1ec9 c\u00f3 th\u1ec3 truy c\u1eadp trong ch\u00ednh l\u1edbp \u0111\u00f3<\/td>\n<\/tr>\n
#<\/code><\/td>\nB\u1ea3o v\u1ec7<\/td>\nC\u00f3 th\u1ec3 truy c\u1eadp trong l\u1edbp v\u00e0 c\u00e1c l\u1edbp con c\u1ee7a n\u00f3<\/td>\n<\/tr>\n
~<\/code><\/td>\nG\u00f3i<\/td>\nC\u00f3 th\u1ec3 truy c\u1eadp trong c\u00f9ng m\u1ed9t g\u00f3i<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
T\u1ed5ng qu\u00e1t h\u00f3a<\/h3>\n
T\u1ed5ng qu\u00e1t h\u00f3a l\u00e0 m\u1ed9t m\u1ed1i quan h\u1ec7 gi\u1eefa m\u1ed9t \u0111\u1ed1i t\u01b0\u1ee3ng t\u1ed5ng qu\u00e1t (g\u1ecdi l\u00e0 si\u00eau l\u1edbp) v\u00e0 m\u1ed9t lo\u1ea1i c\u1ee5 th\u1ec3 h\u01a1n c\u1ee7a \u0111\u1ed1i t\u01b0\u1ee3ng \u0111\u00f3 (g\u1ecdi l\u00e0 l\u1edbp con). T\u1ed5ng qu\u00e1t h\u00f3a \u0111\u00f4i khi \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 m\u1ed1i quan h\u1ec7 “l\u00e0 m\u1ed9t lo\u1ea1i c\u1ee7a” v\u00e0 \u0111\u01b0\u1ee3c thi\u1ebft l\u1eadp th\u00f4ng qua qu\u00e1 tr\u00ecnh k\u1ebf th\u1eeba.<\/p>\n
Trong s\u01a1 \u0111\u1ed3 l\u1edbp, m\u1ed1i quan h\u1ec7 t\u1ed5ng qu\u00e1t h\u00f3a \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng m\u1ed9t \u0111\u01b0\u1eddng li\u1ec1n h\u01b0\u1edbng v\u1edbi \u0111\u1ea7u m\u0169i t\u00ean l\u1edbn m\u1edf h\u01b0\u1edbng v\u1ec1 l\u1edbp cha.<\/p>\n
\"UML<\/p>\n
L\u1edbp v\u00e0 ph\u01b0\u01a1ng th\u1ee9c tr\u1eebu t\u01b0\u1ee3ng<\/h4>\n
Trong m\u1ed9t c\u1ea5u tr\u00fac k\u1ebf th\u1eeba, c\u00e1c l\u1edbp con tri\u1ec3n khai c\u00e1c chi ti\u1ebft c\u1ee5 th\u1ec3, trong khi l\u1edbp cha \u0111\u1ecbnh ngh\u0129a khung cho c\u00e1c l\u1edbp con c\u1ee7a n\u00f3. L\u1edbp cha c\u0169ng \u0111\u00f3ng vai tr\u00f2 nh\u01b0 m\u1ed9t m\u1eabu cho c\u00e1c ph\u01b0\u01a1ng th\u1ee9c chung s\u1ebd \u0111\u01b0\u1ee3c c\u00e1c l\u1edbp con tri\u1ec3n khai.<\/p>\n
\"Abstract<\/p>\n