{"id":4,"date":"2024-11-19T13:26:09","date_gmt":"2024-11-19T10:26:09","guid":{"rendered":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/?p=4"},"modified":"2024-11-19T14:25:59","modified_gmt":"2024-11-19T11:25:59","slug":"java-design-patterns","status":"publish","type":"post","link":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/2024\/11\/19\/java-design-patterns\/","title":{"rendered":"Java Design Patterns"},"content":{"rendered":"<h1 data-testid=\"storyTitle\" data-selectable-paragraph=\"\">JAVA II - \u03a7\u03b1\u03c1\u03bf\u03ba\u03cc\u03c0\u03b5\u03b9\u03bf \u03a0\u03b1\u03bd\u03b5\u03c0\u03b9\u03c3\u03c4\u03ae\u03bc\u03b9\u03bf<\/h1>\n<p><a href=\"https:\/\/dit.hua.gr\/index.php\/el\/\">https:\/\/dit.hua.gr\/index.php\/el\/<\/a><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h1 id=\"9254\" class=\"pw-post-title gs gt gu bf gv gw gx gy gz ha hb hc hd he hf hg hh hi hj hk hl hm hn ho hp hq hr hs ht hu bk\" data-testid=\"storyTitle\" data-selectable-paragraph=\"\">\u0391\u03c0\u03b1\u03c1\u03b1\u03af\u03c4\u03b7\u03c4\u03b1 Java Design Patterns \u03c0\u03bf\u03c5 \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b3\u03bd\u03c9\u03c1\u03af\u03b6\u03b5\u03c4\u03b1\u03b9<\/h1>\n<p>&nbsp;<\/p>\n<p>\u03a3\u03b5 \u03b1\u03c5\u03c4\u03ae \u03c4\u03b7\u03bd \u03b1\u03bd\u03ac\u03c1\u03c4\u03b7\u03c3\u03b7, \u03b8\u03b1 \u03b5\u03be\u03b7\u03b3\u03ae\u03c3\u03c9 \u03c4\u03b1 \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2, \u03c4\u03b7\u03bd \u03b1\u03bd\u03b1\u03b3\u03ba\u03b1\u03b9\u03cc\u03c4\u03b7\u03c4\u03ac \u03c4\u03bf\u03c5\u03c2 \u03ba\u03b1\u03b9 \u03b8\u03b1 \u03b5\u03bc\u03b2\u03b1\u03b8\u03cd\u03bd\u03c9 \u03c3\u03b5 \u03ba\u03ac\u03c0\u03bf\u03b9\u03b1 \u03b1\u03c0\u03cc \u03c4\u03b1 \u03c0\u03b9\u03bf \u03b4\u03b7\u03bc\u03bf\u03c6\u03b9\u03bb\u03ae, \u03cc\u03c0\u03c9\u03c2 \u03c4\u03b1 Singleton, Strategy, Factory, Abstract Factory \u03ba\u03b1\u03b9 Builder.<\/p>\n<p><strong>\u03a4\u03b9 \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03b1 Design Patterns;<\/strong><\/p>\n<p>\u03a4\u03b1 (Design Patterns) \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 \u03b5\u03af\u03bd\u03b1\u03b9 \u03b5\u03c0\u03b1\u03bd\u03b1\u03c7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03b9\u03ae\u03c3\u03b9\u03bc\u03b5\u03c2 \u03bb\u03cd\u03c3\u03b5\u03b9\u03c2 \u03c3\u03b5 \u03b5\u03c0\u03b1\u03bd\u03b1\u03bb\u03b1\u03bc\u03b2\u03b1\u03bd\u03cc\u03bc\u03b5\u03bd\u03b1 \u03c0\u03c1\u03bf\u03b2\u03bb\u03ae\u03bc\u03b1\u03c4\u03b1 \u03c3\u03c4\u03b7\u03bd \u03b1\u03bd\u03ac\u03c0\u03c4\u03c5\u03be\u03b7 \u03bb\u03bf\u03b3\u03b9\u03c3\u03bc\u03b9\u03ba\u03bf\u03cd. \u0391\u03bd\u03c4\u03b9\u03c0\u03c1\u03bf\u03c3\u03c9\u03c0\u03b5\u03cd\u03bf\u03c5\u03bd \u03c4\u03b9\u03c2 \u03b2\u03ad\u03bb\u03c4\u03b9\u03c3\u03c4\u03b5\u03c2 \u03c0\u03c1\u03b1\u03ba\u03c4\u03b9\u03ba\u03ad\u03c2 \u03b3\u03b9\u03b1 \u03c4\u03b7\u03bd \u03b5\u03c0\u03af\u03bb\u03c5\u03c3\u03b7 \u03bf\u03c1\u03b9\u03c3\u03bc\u03ad\u03bd\u03c9\u03bd \u03c4\u03cd\u03c0\u03c9\u03bd \u03c0\u03c1\u03bf\u03b2\u03bb\u03b7\u03bc\u03ac\u03c4\u03c9\u03bd \u03bc\u03b5 \u03ad\u03bd\u03b1\u03bd \u03c3\u03c5\u03bd\u03b5\u03ba\u03c4\u03b9\u03ba\u03cc, \u03b1\u03c0\u03bf\u03b4\u03bf\u03c4\u03b9\u03ba\u03cc \u03ba\u03b1\u03b9 \u03c3\u03c5\u03bd\u03c4\u03b7\u03c1\u03ae\u03c3\u03b9\u03bc\u03bf \u03c4\u03c1\u03cc\u03c0\u03bf, \u03c0\u03c1\u03bf\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03bf\u03c5 \u03bd\u03b1 \u03c3\u03c7\u03b5\u03b4\u03b9\u03ac\u03c3\u03bf\u03c5\u03bc\u03b5 \u03b9\u03c3\u03c7\u03c5\u03c1\u03ac \u03c3\u03c5\u03c3\u03c4\u03ae\u03bc\u03b1\u03c4\u03b1 \u03bb\u03bf\u03b3\u03b9\u03c3\u03bc\u03b9\u03ba\u03bf\u03cd.<\/p>\n<p>\u03a4\u03bf \u03b4\u03b9\u03ac\u03c3\u03b7\u03bc\u03bf \u03b2\u03b9\u03b2\u03bb\u03af\u03bf \u201cDesign Patterns: Elements of Reusable Object-Oriented Software\u201d, \u03b3\u03bd\u03c9\u03c3\u03c4\u03cc \u03ba\u03b1\u03b9 \u03c9\u03c2 \u03b2\u03b9\u03b2\u03bb\u03af\u03bf GoF, \u03b4\u03b7\u03bc\u03bf\u03c3\u03b9\u03b5\u03cd\u03b8\u03b7\u03ba\u03b5 \u03c4\u03b7 \u03b4\u03b5\u03ba\u03b1\u03b5\u03c4\u03af\u03b1 \u03c4\u03bf\u03c5 '90. \u039a\u03b1\u03c4\u03ad\u03b3\u03c1\u03b1\u03c8\u03b5 23 \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 \u03ba\u03b1\u03b9 \u03b3\u03c1\u03ac\u03c6\u03c4\u03b7\u03ba\u03b5 \u03b1\u03c0\u03cc \u03c4\u03bf\u03c5\u03c2 Erich Gamma, Richard Helm, Ralph Johnson \u03ba\u03b1\u03b9 John Vlissides \u2014 \u03c4\u03bf\u03c5\u03c2 \u03c3\u03c5\u03b3\u03b3\u03c1\u03b1\u03c6\u03b5\u03af\u03c2 \u03c4\u03b7\u03c2 \u00ab\u03a3\u03c5\u03bc\u03bc\u03bf\u03c1\u03af\u03b1\u03c2 \u03c4\u03c9\u03bd \u03a4\u03b5\u03c3\u03c3\u03ac\u03c1\u03c9\u03bd\u00bb (Gang of Four, GoF).<\/p>\n<p>\u03a4\u03b1 \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03b5\u03af\u03bd\u03b1\u03b9 \u03bf\u03c1\u03b3\u03b1\u03bd\u03c9\u03bc\u03ad\u03bd\u03b1 \u03c3\u03b5 \u03c4\u03c1\u03b5\u03b9\u03c2 \u03ba\u03cd\u03c1\u03b9\u03b5\u03c2 \u03ba\u03b1\u03c4\u03b7\u03b3\u03bf\u03c1\u03af\u03b5\u03c2:<\/p>\n<p><strong>\u0394\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03b9\u03ba\u03ac \u03a3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03a3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 (Creational Design Patterns):<\/strong><\/p>\n<p>\u0391\u03c5\u03c4\u03ac \u03c0\u03b1\u03c1\u03ad\u03c7\u03bf\u03c5\u03bd \u03c4\u03c1\u03cc\u03c0\u03bf\u03c5\u03c2 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1\u03c2 \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd \u03b5\u03bd\u03ce \u03ba\u03c1\u03cd\u03b2\u03bf\u03c5\u03bd \u03c4\u03b9\u03c2 \u03bb\u03b5\u03c0\u03c4\u03bf\u03bc\u03ad\u03c1\u03b5\u03b9\u03b5\u03c2 \u03c5\u03bb\u03bf\u03c0\u03bf\u03af\u03b7\u03c3\u03b7\u03c2 \u03c4\u03bf\u03c5 \u03c0\u03ce\u03c2 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03bf\u03cd\u03bd\u03c4\u03b1\u03b9 \u03c4\u03b1 \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03af\u03bc\u03b5\u03bd\u03b1. \u0391\u03c0\u03bf\u03bc\u03bf\u03bd\u03ce\u03bd\u03bf\u03c5\u03bd \u03c4\u03b7 \u03b4\u03b9\u03b1\u03b4\u03b9\u03ba\u03b1\u03c3\u03af\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1\u03c2, \u03ba\u03ac\u03bd\u03bf\u03bd\u03c4\u03ac\u03c2 \u03c4\u03b7\u03bd \u03c0\u03b9\u03bf \u03b5\u03c5\u03ad\u03bb\u03b9\u03ba\u03c4\u03b7 \u03ba\u03b1\u03b9 \u03b5\u03c0\u03b5\u03ba\u03c4\u03ac\u03c3\u03b9\u03bc\u03b7.<\/p>\n<p>\u039f\u03c1\u03b9\u03c3\u03bc\u03ad\u03bd\u03b1 \u03ba\u03bf\u03b9\u03bd\u03ac \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03b9\u03ba\u03ac \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 \u03b5\u03af\u03bd\u03b1\u03b9: Singleton, Factory, Abstract Factory, Builder \u03ba\u03b1\u03b9 Prototype.<\/p>\n<p><strong>\u0394\u03bf\u03bc\u03b9\u03ba\u03ac \u03a3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03a3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 (Structural Design Patterns):<\/strong><\/p>\n<p>\u0391\u03c5\u03c4\u03ac \u03b1\u03c6\u03bf\u03c1\u03bf\u03cd\u03bd \u03c4\u03b7 \u03c3\u03cd\u03bd\u03b8\u03b5\u03c3\u03b7 \u03ba\u03bb\u03ac\u03c3\u03b5\u03c9\u03bd \u03ba\u03b1\u03b9 \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd \u03b3\u03b9\u03b1 \u03c4\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 \u03bc\u03b5\u03b3\u03b1\u03bb\u03cd\u03c4\u03b5\u03c1\u03c9\u03bd \u03b4\u03bf\u03bc\u03ce\u03bd, \u03ad\u03c4\u03c3\u03b9 \u03ce\u03c3\u03c4\u03b5 \u03bd\u03b1 \u03c3\u03c5\u03bd\u03b5\u03c1\u03b3\u03ac\u03b6\u03bf\u03bd\u03c4\u03b1\u03b9 \u03b1\u03c0\u03bf\u03c4\u03b5\u03bb\u03b5\u03c3\u03bc\u03b1\u03c4\u03b9\u03ba\u03ac.<\/p>\n<p>\u039f\u03c1\u03b9\u03c3\u03bc\u03ad\u03bd\u03b1 \u03ba\u03bf\u03b9\u03bd\u03ac \u03b4\u03bf\u03bc\u03b9\u03ba\u03ac \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 \u03b5\u03af\u03bd\u03b1\u03b9: Adapter, Bridge, Composite, Decorator, Facade \u03ba\u03b1\u03b9 Proxy.<\/p>\n<p><strong>\u03a3\u03c5\u03bc\u03c0\u03b5\u03c1\u03b9\u03c6\u03bf\u03c1\u03b9\u03ba\u03ac \u03a3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03a3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 (Behavioral Design Patterns):<\/strong><\/p>\n<p>\u0391\u03c5\u03c4\u03ac \u03b5\u03c0\u03b9\u03ba\u03b5\u03bd\u03c4\u03c1\u03ce\u03bd\u03bf\u03bd\u03c4\u03b1\u03b9 \u03c3\u03c4\u03b7\u03bd \u03b5\u03c0\u03b9\u03ba\u03bf\u03b9\u03bd\u03c9\u03bd\u03af\u03b1 \u03bc\u03b5\u03c4\u03b1\u03be\u03cd \u03c4\u03c9\u03bd \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd \u03ba\u03b1\u03b9 \u03c0\u03ce\u03c2 \u03b1\u03bb\u03bb\u03b7\u03bb\u03b5\u03c0\u03b9\u03b4\u03c1\u03bf\u03cd\u03bd \u03bc\u03b5\u03c4\u03b1\u03be\u03cd \u03c4\u03bf\u03c5\u03c2 \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03c0\u03b5\u03c4\u03cd\u03c7\u03bf\u03c5\u03bd \u03ad\u03bd\u03b1\u03bd \u03ba\u03bf\u03b9\u03bd\u03cc \u03c3\u03c4\u03cc\u03c7\u03bf.<\/p>\n<p><strong>\u03a4\u03b1 \u039f\u03c6\u03ad\u03bb\u03b7 \u03c4\u03c9\u03bd \u03a3\u03c7\u03b5\u03b4\u03af\u03c9\u03bd \u03a3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2<\/strong><\/p>\n<ul>\n<li><strong>\u0395\u03c0\u03b1\u03bd\u03b1\u03c7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03af\u03b7\u03c3\u03b7<\/strong>: \u03a0\u03b1\u03c1\u03ad\u03c7\u03bf\u03c5\u03bd \u03bb\u03cd\u03c3\u03b5\u03b9\u03c2 \u03c3\u03b5 \u03ba\u03bf\u03b9\u03bd\u03ac \u03c0\u03c1\u03bf\u03b2\u03bb\u03ae\u03bc\u03b1\u03c4\u03b1 \u03c0\u03bf\u03c5 \u03bc\u03c0\u03bf\u03c1\u03bf\u03cd\u03bd \u03bd\u03b1 \u03b5\u03c0\u03b1\u03bd\u03b1\u03c7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03b9\u03b7\u03b8\u03bf\u03cd\u03bd \u03c3\u03b5 \u03b4\u03b9\u03ac\u03c6\u03bf\u03c1\u03b1 \u03ad\u03c1\u03b3\u03b1.<\/li>\n<li><strong>\u0395\u03c5\u03b5\u03bb\u03b9\u03be\u03af\u03b1<\/strong>: \u039a\u03ac\u03bd\u03bf\u03c5\u03bd \u03c4\u03bf\u03bd \u03ba\u03ce\u03b4\u03b9\u03ba\u03ac \u03bc\u03b1\u03c2 \u03b5\u03c5\u03ad\u03bb\u03b9\u03ba\u03c4\u03bf \u03ba\u03b1\u03b9 \u03c0\u03c1\u03bf\u03c3\u03b1\u03c1\u03bc\u03cc\u03c3\u03b9\u03bc\u03bf \u03c3\u03b5 \u03b1\u03bb\u03bb\u03b1\u03b3\u03ad\u03c2. \u0395\u03c0\u03b9\u03c4\u03c1\u03ad\u03c0\u03bf\u03c5\u03bd \u03c4\u03b7 \u03bc\u03b5\u03c4\u03b1\u03c4\u03c1\u03bf\u03c0\u03ae \u03c4\u03bf\u03c5 \u03ba\u03ce\u03b4\u03b9\u03ba\u03b1 \u03bc\u03b5 \u03b5\u03bb\u03ac\u03c7\u03b9\u03c3\u03c4\u03bf \u03b1\u03bd\u03c4\u03af\u03ba\u03c4\u03c5\u03c0\u03bf \u03c3\u03c4\u03bf\u03bd \u03c5\u03c0\u03ac\u03c1\u03c7\u03bf\u03bd\u03c4\u03b1 \u03ba\u03ce\u03b4\u03b9\u03ba\u03b1.<\/li>\n<li><strong>\u03a3\u03c5\u03bd\u03b5\u03c1\u03b3\u03b1\u03c3\u03af\u03b1<\/strong>: \u0395\u03af\u03bd\u03b1\u03b9 \u03b5\u03c5\u03c1\u03ad\u03c9\u03c2 \u03b3\u03bd\u03c9\u03c3\u03c4\u03ac \u03c3\u03c4\u03bf\u03c5\u03c2 \u03c0\u03c1\u03bf\u03b3\u03c1\u03b1\u03bc\u03bc\u03b1\u03c4\u03b9\u03c3\u03c4\u03ad\u03c2. \u039c\u03c0\u03bf\u03c1\u03bf\u03cd\u03bc\u03b5 \u03bd\u03b1 \u03ba\u03b1\u03c4\u03b1\u03bd\u03bf\u03ae\u03c3\u03bf\u03c5\u03bc\u03b5 \u03ba\u03b1\u03b9 \u03bd\u03b1 \u03c3\u03c5\u03bd\u03b5\u03b9\u03c3\u03c6\u03ad\u03c1\u03bf\u03c5\u03bc\u03b5 \u03c3\u03c4\u03bf\u03bd \u03ba\u03ce\u03b4\u03b9\u03ba\u03b1 \u03b5\u03cd\u03ba\u03bf\u03bb\u03b1.<\/li>\n<li><strong>\u0395\u03c0\u03af\u03bb\u03c5\u03c3\u03b7 \u03a0\u03c1\u03bf\u03b2\u03bb\u03b7\u03bc\u03ac\u03c4\u03c9\u03bd<\/strong>: \u039c\u03b1\u03c2 \u03b2\u03bf\u03b7\u03b8\u03bf\u03cd\u03bd \u03bd\u03b1 \u03bb\u03cd\u03c3\u03bf\u03c5\u03bc\u03b5 \u03b5\u03c0\u03b1\u03bd\u03b1\u03bb\u03b1\u03bc\u03b2\u03b1\u03bd\u03cc\u03bc\u03b5\u03bd\u03b1 \u03c0\u03c1\u03bf\u03b2\u03bb\u03ae\u03bc\u03b1\u03c4\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 \u03c7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03b9\u03ce\u03bd\u03c4\u03b1\u03c2 \u03c4\u03b9\u03c2 \u03ba\u03b1\u03bb\u03cd\u03c4\u03b5\u03c1\u03b5\u03c2 \u03bb\u03cd\u03c3\u03b5\u03b9\u03c2.<\/li>\n<\/ul>\n<p>\u0391\u03c5\u03c4\u03cc \u03c3\u03c5\u03bc\u03b2\u03b1\u03b4\u03af\u03b6\u03b5\u03b9 \u03c0\u03bb\u03ae\u03c1\u03c9\u03c2 \u03bc\u03b5 \u03c4\u03b7\u03bd \u03b1\u03c1\u03c7\u03ae \u03c4\u03bf\u03c5 Solid, \u03c4\u03b7\u03bd \u03b1\u03c1\u03c7\u03ae \u03b1\u03bd\u03bf\u03b9\u03c7\u03c4\u03ae\u03c2-\u03ba\u03bb\u03b5\u03b9\u03c3\u03c4\u03ae\u03c2: \u03b1\u03bd\u03bf\u03b9\u03c7\u03c4\u03cc \u03b3\u03b9\u03b1 \u03b5\u03c0\u03ad\u03ba\u03c4\u03b1\u03c3\u03b7, \u03b1\u03bb\u03bb\u03ac \u03ba\u03bb\u03b5\u03b9\u03c3\u03c4\u03cc \u03b3\u03b9\u03b1 \u03c4\u03c1\u03bf\u03c0\u03bf\u03c0\u03bf\u03af\u03b7\u03c3\u03b7.<\/p>\n<p>&nbsp;<\/p>\n<div class=\"ab cb ox oy oz pa\" role=\"separator\"><\/div>\n<div class=\"gn go gp gq gr\">\n<div class=\"ab cb\">\n<div class=\"ci bh fz ga gb gc\">\n<h1 id=\"c9f1\" class=\"ns nt gu bf nu nv pf nx ny nz pg ob oc od ph of og oh pi oj ok ol pj on oo op bk\" data-selectable-paragraph=\"\">Singleton Pattern:<\/h1>\n<p>\u03a7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03b9\u03bf\u03cd\u03bc\u03b5 \u03c4\u03bf \u03c3\u03c7\u03ad\u03b4\u03b9\u03bf Singleton \u03cc\u03c4\u03b1\u03bd \u03c7\u03c1\u03b5\u03b9\u03b1\u03b6\u03cc\u03bc\u03b1\u03c3\u03c4\u03b5 \u03bd\u03b1 \u03ad\u03c7\u03bf\u03c5\u03bc\u03b5 \u03bc\u03cc\u03bd\u03bf \u03bc\u03af\u03b1 \u03c0\u03b1\u03c1\u03bf\u03c5\u03c3\u03af\u03b1 \u03c4\u03b7\u03c2 \u03ba\u03bb\u03ac\u03c3\u03b7\u03c2 \u03bc\u03b1\u03c2 \u03ba\u03b1\u03b9 \u03bd\u03b1 \u03c0\u03b1\u03c1\u03ad\u03c7\u03bf\u03c5\u03bc\u03b5 \u03ad\u03bd\u03b1 \u03c0\u03b1\u03b3\u03ba\u03cc\u03c3\u03bc\u03b9\u03bf \u03c3\u03b7\u03bc\u03b5\u03af\u03bf \u03c0\u03c1\u03cc\u03c3\u03b2\u03b1\u03c3\u03b7\u03c2 \u03c3\u03b5 \u03b1\u03c5\u03c4\u03ae\u03bd.<\/p>\n<p>\u03a5\u03c0\u03ac\u03c1\u03c7\u03bf\u03c5\u03bd \u03b4\u03cd\u03bf \u03bc\u03bf\u03c1\u03c6\u03ad\u03c2 \u03c4\u03bf\u03c5 \u03c3\u03c7\u03b5\u03b4\u03af\u03bf\u03c5 Singleton:<\/p>\n<ol>\n<li><strong>\u03a0\u03c1\u03cc\u03c9\u03c1\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 (Early instantiation):<\/strong> \u0394\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03bf\u03cd\u03bc\u03b5 \u03c4\u03b7\u03bd \u03c0\u03b1\u03c1\u03bf\u03c5\u03c3\u03af\u03b1 \u03ba\u03b1\u03c4\u03ac \u03c4\u03b7 \u03c6\u03cc\u03c1\u03c4\u03c9\u03c3\u03b7 \u03c4\u03b7\u03c2 \u03b5\u03c6\u03b1\u03c1\u03bc\u03bf\u03b3\u03ae\u03c2.<\/li>\n<li><strong>\u039a\u03b1\u03b8\u03c5\u03c3\u03c4\u03b5\u03c1\u03b7\u03bc\u03ad\u03bd\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 (Lazy instantiation):<\/strong> \u0394\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03bf\u03cd\u03bc\u03b5 \u03c4\u03b7\u03bd \u03c0\u03b1\u03c1\u03bf\u03c5\u03c3\u03af\u03b1 \u03cc\u03c4\u03b1\u03bd \u03b1\u03c0\u03b1\u03b9\u03c4\u03b5\u03af\u03c4\u03b1\u03b9.<\/li>\n<\/ol>\n<p>\u0393\u03b9\u03b1 \u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03ae\u03c3\u03bf\u03c5\u03bc\u03b5 \u03c4\u03b7\u03bd \u03ba\u03bb\u03ac\u03c3\u03b7 Singleton, \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03ad\u03c7\u03bf\u03c5\u03bc\u03b5 \u03c4\u03b1 \u03b5\u03be\u03ae\u03c2:<\/p>\n<ul>\n<li><strong>\u03a3\u03c4\u03b1\u03c4\u03b9\u03ba\u03cc \u03bc\u03ad\u03bb\u03bf\u03c2 \u03c4\u03b7\u03c2 \u03ba\u03bb\u03ac\u03c3\u03b7\u03c2:<\/strong> \u0388\u03bd\u03b1 \u03c3\u03c4\u03b1\u03c4\u03b9\u03ba\u03cc \u03c0\u03b5\u03b4\u03af\u03bf \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03b1\u03c0\u03bf\u03b8\u03b7\u03ba\u03b5\u03cd\u03c3\u03bf\u03c5\u03bc\u03b5 \u03c4\u03b7 \u03bc\u03bf\u03bd\u03b1\u03b4\u03b9\u03ba\u03ae \u03c0\u03b1\u03c1\u03bf\u03c5\u03c3\u03af\u03b1 \u03c4\u03b7\u03c2 \u03ba\u03bb\u03ac\u03c3\u03b7\u03c2.<\/li>\n<li><strong>\u0399\u03b4\u03b9\u03c9\u03c4\u03b9\u03ba\u03cc\u03c2 \u03ba\u03b1\u03c4\u03b1\u03c3\u03ba\u03b5\u03c5\u03b1\u03c3\u03c4\u03ae\u03c2 (private constructor):<\/strong> \u039f \u03ba\u03b1\u03c4\u03b1\u03c3\u03ba\u03b5\u03c5\u03b1\u03c3\u03c4\u03ae\u03c2 \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b5\u03af\u03bd\u03b1\u03b9 \u03b9\u03b4\u03b9\u03c9\u03c4\u03b9\u03ba\u03cc\u03c2 \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03b1\u03c0\u03bf\u03c4\u03c1\u03ad\u03c8\u03b5\u03b9 \u03c4\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 \u03bd\u03ad\u03c9\u03bd \u03b1\u03bd\u03c4\u03b9\u03b3\u03c1\u03ac\u03c6\u03c9\u03bd \u03c4\u03b7\u03c2 \u03ba\u03bb\u03ac\u03c3\u03b7\u03c2 \u03b1\u03c0\u03cc \u03ad\u03be\u03c9.<\/li>\n<li><strong>\u03a3\u03c4\u03b1\u03c4\u03b9\u03ba\u03ae \u03bc\u03ad\u03b8\u03bf\u03b4\u03bf\u03c2 \u03b5\u03c1\u03b3\u03bf\u03c3\u03c4\u03b1\u03c3\u03af\u03bf\u03c5 (static factory method):<\/strong> \u03a0\u03b1\u03c1\u03ad\u03c7\u03b5\u03b9 \u03c4\u03bf \u03c0\u03b1\u03b3\u03ba\u03cc\u03c3\u03bc\u03b9\u03bf \u03c3\u03b7\u03bc\u03b5\u03af\u03bf \u03c0\u03c1\u03cc\u03c3\u03b2\u03b1\u03c3\u03b7\u03c2 \u03b3\u03b9\u03b1 \u03c4\u03bf \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03af\u03bc\u03b5\u03bd\u03bf Singleton \u03ba\u03b1\u03b9 \u03b5\u03c0\u03b9\u03c3\u03c4\u03c1\u03ad\u03c6\u03b5\u03b9 \u03c4\u03b7\u03bd \u03c0\u03b1\u03c1\u03bf\u03c5\u03c3\u03af\u03b1 \u03c3\u03c4\u03b7\u03bd \u03ba\u03bb\u03ac\u03c3\u03b7 \u03c0\u03b5\u03bb\u03ac\u03c4\u03b7.<\/li>\n<\/ul>\n<p>\u0395\u03b4\u03ce \u03b5\u03af\u03bd\u03b1\u03b9 \u03ad\u03bd\u03b1 \u03c0\u03b1\u03c1\u03ac\u03b4\u03b5\u03b9\u03b3\u03bc\u03b1 \u03c5\u03bb\u03bf\u03c0\u03bf\u03af\u03b7\u03c3\u03b7\u03c2 \u03c4\u03bf\u03c5 \u03c3\u03c7\u03b5\u03b4\u03af\u03bf\u03c5 Singleton \u03bc\u03b5 \u03c0\u03c1\u03cc\u03c9\u03c1\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 (eager loading):<\/p>\n<pre class=\"nh ni nj nk nl ps pt pu bp pv bb bk\"><span class=\"pw nt gu pt b bg px py l pz qa\" data-selectable-paragraph=\"\"><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title.class\">NotificationService<\/span> {\r\n\r\n    <span class=\"hljs-comment\">\/\/ Can also be initialized in a static block<\/span>\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">final<\/span> <span class=\"hljs-type\">NotificationService<\/span> <span class=\"hljs-variable\">instance<\/span> <span class=\"hljs-operator\">=<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title.class\">NotificationService<\/span>();\r\n\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-title.function\">NotificationService<\/span><span class=\"hljs-params\">()<\/span> {\r\n    }\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> NotificationService <span class=\"hljs-title.function\">getInstance<\/span><span class=\"hljs-params\">()<\/span> {\r\n        <span class=\"hljs-keyword\">return<\/span> instance;\r\n    }\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title.function\">sendNotification<\/span><span class=\"hljs-params\">(String message)<\/span> {\r\n        <span class=\"hljs-comment\">\/\/ Logic to send notification<\/span>\r\n        System.out.println(<span class=\"hljs-string\">\"Notification sent \"<\/span> + message);\r\n    }\r\n}\r\n\r\n\r\n<\/span><\/pre>\n<h1 id=\"043b\" class=\"ns nt gu bf nu nv nw nx ny nz oa ob oc od oe of og oh oi oj ok ol om on oo op bk\" data-selectable-paragraph=\"\">Factory Pattern<\/h1>\n<p>\u03a4\u03bf \u03c3\u03c7\u03ad\u03b4\u03b9\u03bf Factory \u03b5\u03af\u03bd\u03b1\u03b9 \u03ad\u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03b9\u03ba\u03cc \u03c3\u03c7\u03ad\u03b4\u03b9\u03bf \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2 \u03c0\u03bf\u03c5 \u03c0\u03b1\u03c1\u03ad\u03c7\u03b5\u03b9 \u03ad\u03bd\u03b1\u03bd \u03c4\u03c1\u03cc\u03c0\u03bf \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03bf\u03cd\u03bc\u03b5 \u03bc\u03b9\u03b1 \u03bf\u03bc\u03ac\u03b4\u03b1 \u03c3\u03c7\u03b5\u03c4\u03b9\u03ba\u03ce\u03bd \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd \u03b2\u03b1\u03c3\u03b9\u03c3\u03bc\u03ad\u03bd\u03c9\u03bd \u03c3\u03b5 \u03ba\u03ac\u03c0\u03bf\u03b9\u03b1 \u03ba\u03c1\u03b9\u03c4\u03ae\u03c1\u03b9\u03b1, \u03c7\u03c9\u03c1\u03af\u03c2 \u03bd\u03b1 \u03b5\u03ba\u03b8\u03ad\u03c4\u03bf\u03c5\u03bc\u03b5 \u03c4\u03b9\u03c2 \u03c3\u03c5\u03b3\u03ba\u03b5\u03ba\u03c1\u03b9\u03bc\u03ad\u03bd\u03b5\u03c2 \u03ba\u03bb\u03ac\u03c3\u03b5\u03b9\u03c2 \u03c4\u03bf\u03c5\u03c2. \u0391\u03c0\u03bf\u03bc\u03bf\u03bd\u03ce\u03bd\u03b5\u03b9 \u03c4\u03b7 \u03b4\u03b9\u03b1\u03b4\u03b9\u03ba\u03b1\u03c3\u03af\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1\u03c2 \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd (instantiation).<\/p>\n<p>\u0393\u03b9\u03b1 \u03bd\u03b1 \u03c4\u03bf \u03c5\u03bb\u03bf\u03c0\u03bf\u03b9\u03ae\u03c3\u03bf\u03c5\u03bc\u03b5, \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03ae\u03c3\u03bf\u03c5\u03bc\u03b5 \u03bc\u03b9\u03b1 \u03b4\u03b9\u03b5\u03c0\u03b1\u03c6\u03ae (interface) \u03b3\u03b9\u03b1 \u03c4\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd, \u03ba\u03b1\u03b9 \u03bd\u03b1 \u03ad\u03c7\u03bf\u03c5\u03bc\u03b5 \u03c3\u03c5\u03b3\u03ba\u03b5\u03ba\u03c1\u03b9\u03bc\u03ad\u03bd\u03b5\u03c2 \u03ba\u03bb\u03ac\u03c3\u03b5\u03b9\u03c2 \u03c0\u03bf\u03c5 \u03c5\u03bb\u03bf\u03c0\u03bf\u03b9\u03bf\u03cd\u03bd \u03b1\u03c5\u03c4\u03ae \u03c4\u03b7\u03bd \u03b4\u03b9\u03b5\u03c0\u03b1\u03c6\u03ae \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03bf\u03cd\u03bd \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03af\u03bc\u03b5\u03bd\u03b1 \u03c3\u03c5\u03b3\u03ba\u03b5\u03ba\u03c1\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd \u03c4\u03cd\u03c0\u03c9\u03bd.<\/p>\n<p>\u0395\u03b4\u03ce \u03b5\u03af\u03bd\u03b1\u03b9 \u03ad\u03bd\u03b1 \u03c0\u03b1\u03c1\u03ac\u03b4\u03b5\u03b9\u03b3\u03bc\u03b1 \u03b3\u03b9\u03b1 \u03c4\u03b7 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03af\u03b1 \u03b4\u03b9\u03b1\u03c6\u03bf\u03c1\u03b5\u03c4\u03b9\u03ba\u03ce\u03bd \u03bc\u03b5\u03b8\u03cc\u03b4\u03c9\u03bd \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ae\u03c2:<\/p>\n<pre class=\"nh ni nj nk nl ps pt pu bp pv bb bk\"><span id=\"16f4\" class=\"pw nt gu pt b bg px py l pz qa\" data-selectable-paragraph=\"\"><span class=\"hljs-comment\">\/\/ Payment interface<\/span>\r\n<span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">interface<\/span> <span class=\"hljs-title.class\">Payment<\/span> {\r\n    <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title.function\">processPayment<\/span><span class=\"hljs-params\">()<\/span>;\r\n}\r\n\r\n<span class=\"hljs-comment\">\/\/ Implementations of Payment interface<\/span>\r\n<span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title.class\">CreditCardPayment<\/span> <span class=\"hljs-keyword\">implements<\/span> <span class=\"hljs-title.class\">Payment<\/span> {\r\n\r\n    <span class=\"hljs-meta\">@Override<\/span>\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title.function\">processPayment<\/span><span class=\"hljs-params\">()<\/span> {\r\n        System.out.println(<span class=\"hljs-string\">\"Processing payment using Credit Card...\"<\/span>);\r\n    }\r\n}\r\n\r\n<span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title.class\">PayPalPayment<\/span> <span class=\"hljs-keyword\">implements<\/span> <span class=\"hljs-title.class\">Payment<\/span> {\r\n\r\n    <span class=\"hljs-meta\">@Override<\/span>\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title.function\">processPayment<\/span><span class=\"hljs-params\">()<\/span> {\r\n        System.out.println(<span class=\"hljs-string\">\"Processing payment using PayPal...\"<\/span>);\r\n    }\r\n}\r\n\r\n\r\n<span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title.class\">PaymentFactory<\/span> {\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> Payment <span class=\"hljs-title.function\">createPayment<\/span><span class=\"hljs-params\">(PayMethod payMethod)<\/span> {\r\n      <span class=\"hljs-keyword\">if<\/span> (payMethod == PayMethod.CREDIT_CARD) {\r\n        <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title.class\">CreditCardPayment<\/span>();\r\n      } <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (payMethod == PayMethod.PayPal) {\r\n        <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title.class\">PayPalPayment<\/span>();\r\n      }\r\n    }\r\n  }\r\n\r\n<span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title.class\">FactoryClient<\/span> {\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title.function\">main<\/span><span class=\"hljs-params\">(String[] args)<\/span> {\r\n        <span class=\"hljs-comment\">\/\/ Using the factory to create Credit Card and PayPal payments<\/span>\r\n        <span class=\"hljs-type\">Payment<\/span> <span class=\"hljs-variable\">creditCardPayment<\/span> <span class=\"hljs-operator\">=<\/span> PaymentFactory.createPayment(PayMethod.CREDIT_CARD);\r\n        creditCardPayment.processPayment();\r\n\r\n        <span class=\"hljs-type\">Payment<\/span> <span class=\"hljs-variable\">payPalPayment<\/span> <span class=\"hljs-operator\">=<\/span> PaymentFactory.createPayment(PayMethod.PayPal);;\r\n        payPalPayment.processPayment();\r\n    }\r\n}\r\n\r\n\r\n<\/span><\/pre>\n<h3>\u0395\u03c0\u03b5\u03be\u03ae\u03b3\u03b7\u03c3\u03b7:<\/h3>\n<ol>\n<li><strong>PaymentMethod<\/strong>: \u0395\u03af\u03bd\u03b1\u03b9 \u03b7 \u03b4\u03b9\u03b5\u03c0\u03b1\u03c6\u03ae \u03c0\u03bf\u03c5 \u03ba\u03b1\u03b8\u03bf\u03c1\u03af\u03b6\u03b5\u03b9 \u03c4\u03b7 \u03bc\u03ad\u03b8\u03bf\u03b4\u03bf <code>processPayment<\/code>, \u03c4\u03b7\u03bd \u03bf\u03c0\u03bf\u03af\u03b1 \u03b8\u03b1 \u03c5\u03bb\u03bf\u03c0\u03bf\u03b9\u03bf\u03cd\u03bd \u03bf\u03b9 \u03ba\u03bb\u03ac\u03c3\u03b5\u03b9\u03c2 \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ce\u03bd.<\/li>\n<li><strong>CreditCardPayment<\/strong> \u03ba\u03b1\u03b9 <strong>PayPalPayment<\/strong>: \u0395\u03af\u03bd\u03b1\u03b9 \u03bf\u03b9 \u03c3\u03c5\u03b3\u03ba\u03b5\u03ba\u03c1\u03b9\u03bc\u03ad\u03bd\u03b5\u03c2 \u03c5\u03bb\u03bf\u03c0\u03bf\u03b9\u03ae\u03c3\u03b5\u03b9\u03c2 \u03c4\u03b7\u03c2 \u03b4\u03b9\u03b5\u03c0\u03b1\u03c6\u03ae\u03c2 <code>PaymentMethod<\/code>, \u03c0\u03bf\u03c5 \u03ba\u03b1\u03b8\u03bf\u03c1\u03af\u03b6\u03bf\u03c5\u03bd \u03c0\u03ce\u03c2 \u03bd\u03b1 \u03b5\u03c0\u03b5\u03be\u03b5\u03c1\u03b3\u03b1\u03c3\u03c4\u03bf\u03cd\u03bc\u03b5 \u03c4\u03b9\u03c2 \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ad\u03c2 \u03bc\u03ad\u03c3\u03c9 \u03c0\u03b9\u03c3\u03c4\u03c9\u03c4\u03b9\u03ba\u03ae\u03c2 \u03ba\u03ac\u03c1\u03c4\u03b1\u03c2 \u03ba\u03b1\u03b9 PayPal \u03b1\u03bd\u03c4\u03af\u03c3\u03c4\u03bf\u03b9\u03c7\u03b1.<\/li>\n<li><strong>PaymentFactory<\/strong>: \u03a0\u03b1\u03c1\u03ad\u03c7\u03b5\u03b9 \u03c4\u03b7 \u03bc\u03ad\u03b8\u03bf\u03b4\u03bf <code>getPaymentMethod<\/code>, \u03b7 \u03bf\u03c0\u03bf\u03af\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03b5\u03af \u03c4\u03bf \u03ba\u03b1\u03c4\u03ac\u03bb\u03bb\u03b7\u03bb\u03bf \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03af\u03bc\u03b5\u03bd\u03bf \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ae\u03c2 \u03b2\u03ac\u03c3\u03b5\u03b9 \u03c4\u03bf\u03c5 \u03c4\u03cd\u03c0\u03bf\u03c5 \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ae\u03c2 \u03c0\u03bf\u03c5 \u03b4\u03af\u03bd\u03b5\u03c4\u03b1\u03b9 \u03c9\u03c2 \u03c0\u03b1\u03c1\u03ac\u03bc\u03b5\u03c4\u03c1\u03bf\u03c2.<\/li>\n<li><strong>PaymentDemo<\/strong>: \u03a4\u03bf \u03ba\u03cd\u03c1\u03b9\u03bf \u03c0\u03c1\u03cc\u03b3\u03c1\u03b1\u03bc\u03bc\u03b1 \u03c0\u03bf\u03c5 \u03b4\u03b5\u03af\u03c7\u03bd\u03b5\u03b9 \u03c0\u03ce\u03c2 \u03bd\u03b1 \u03c7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03b9\u03bf\u03cd\u03bc\u03b5 \u03c4\u03bf \u03b5\u03c1\u03b3\u03bf\u03c3\u03c4\u03ac\u03c3\u03b9\u03bf \u03b3\u03b9\u03b1 \u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03ae\u03c3\u03bf\u03c5\u03bc\u03b5 \u03ba\u03b1\u03b9 \u03bd\u03b1 \u03b5\u03c0\u03b5\u03be\u03b5\u03c1\u03b3\u03b1\u03c3\u03c4\u03bf\u03cd\u03bc\u03b5 \u03c4\u03b9\u03c2 \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ad\u03c2.<\/li>\n<\/ol>\n<p>\u039c\u03b5 \u03b1\u03c5\u03c4\u03cc\u03bd \u03c4\u03bf\u03bd \u03c4\u03c1\u03cc\u03c0\u03bf, \u03c4\u03bf \u03b5\u03c1\u03b3\u03bf\u03c3\u03c4\u03ac\u03c3\u03b9\u03bf (Factory) \u03bc\u03b1\u03c2 \u03b5\u03c0\u03b9\u03c4\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b4\u03b7\u03bc\u03b9\u03bf\u03c5\u03c1\u03b3\u03bf\u03cd\u03bc\u03b5 \u03b4\u03b9\u03b1\u03c6\u03bf\u03c1\u03b5\u03c4\u03b9\u03ba\u03bf\u03cd\u03c2 \u03c4\u03cd\u03c0\u03bf\u03c5\u03c2 \u03b1\u03bd\u03c4\u03b9\u03ba\u03b5\u03b9\u03bc\u03ad\u03bd\u03c9\u03bd \u03c0\u03bb\u03b7\u03c1\u03c9\u03bc\u03ae\u03c2 \u03c7\u03c9\u03c1\u03af\u03c2 \u03bd\u03b1 \u03b3\u03bd\u03c9\u03c1\u03af\u03b6\u03bf\u03c5\u03bc\u03b5 \u03c0\u03bf\u03b9\u03b1 \u03ba\u03bb\u03ac\u03c3\u03b7 \u03b8\u03b1 \u03c7\u03c1\u03b7\u03c3\u03b9\u03bc\u03bf\u03c0\u03bf\u03b9\u03b7\u03b8\u03b5\u03af, \u03b5\u03be\u03b1\u03c3\u03c6\u03b1\u03bb\u03af\u03b6\u03bf\u03bd\u03c4\u03b1\u03c2 \u03ad\u03c4\u03c3\u03b9 \u03c4\u03b7\u03bd \u03b1\u03c0\u03bf\u03bc\u03cc\u03bd\u03c9\u03c3\u03b7 \u03c4\u03c9\u03bd \u03bb\u03b5\u03c0\u03c4\u03bf\u03bc\u03b5\u03c1\u03b5\u03b9\u03ce\u03bd \u03c5\u03bb\u03bf\u03c0\u03bf\u03af\u03b7\u03c3\u03b7\u03c2.<\/p>\n<\/div>\n<p><span id=\"16f4\" class=\"pw nt gu pt b bg px py l pz qa\" data-selectable-paragraph=\"\"><iframe allow=\"microphone https:\/\/content.e-me-4all.eu\" src=\"https:\/\/content.e-me-4all.eu\/wp-admin\/admin-ajax.php?action=h5p_embed&id=[eme_content_id 85710]\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\" onload=\"iFrameResize({heightCalculationMethod:'max'})\"><\/iframe><\/span><\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>JAVA II &#8211; \u03a7\u03b1\u03c1\u03bf\u03ba\u03cc\u03c0\u03b5\u03b9\u03bf \u03a0\u03b1\u03bd\u03b5\u03c0\u03b9\u03c3\u03c4\u03ae\u03bc\u03b9\u03bf https:\/\/dit.hua.gr\/index.php\/el\/ &nbsp; &nbsp; \u0391\u03c0\u03b1\u03c1\u03b1\u03af\u03c4\u03b7\u03c4\u03b1 Java Design Patterns \u03c0\u03bf\u03c5 \u03c0\u03c1\u03ad\u03c0\u03b5\u03b9 \u03bd\u03b1 \u03b3\u03bd\u03c9\u03c1\u03af\u03b6\u03b5\u03c4\u03b1\u03b9 &nbsp; \u03a3\u03b5 \u03b1\u03c5\u03c4\u03ae \u03c4\u03b7\u03bd \u03b1\u03bd\u03ac\u03c1\u03c4\u03b7\u03c3\u03b7, \u03b8\u03b1 \u03b5\u03be\u03b7\u03b3\u03ae\u03c3\u03c9 \u03c4\u03b1 \u03c3\u03c7\u03ad\u03b4\u03b9\u03b1 \u03c3\u03c7\u03b5\u03b4\u03af\u03b1\u03c3\u03b7\u03c2, \u03c4\u03b7\u03bd \u03b1\u03bd\u03b1\u03b3\u03ba\u03b1\u03b9\u03cc\u03c4\u03b7\u03c4\u03ac \u03c4\u03bf\u03c5\u03c2 \u03ba\u03b1\u03b9 \u03b8\u03b1 \u03b5\u03bc\u03b2\u03b1\u03b8\u03cd\u03bd\u03c9 \u03c3\u03b5 \u03ba\u03ac\u03c0\u03bf\u03b9\u03b1 \u03b1\u03c0\u03cc \u03c4\u03b1 \u03c0\u03b9\u03bf \u03b4\u03b7\u03bc\u03bf\u03c6\u03b9\u03bb\u03ae, \u03cc\u03c0\u03c9\u03c2 \u03c4\u03b1 Singleton, Strategy, Factory, Abstract Factory \u03ba\u03b1\u03b9 Builder. \u03a4\u03b9 \u03b5\u03af\u03bd\u03b1\u03b9 \u03c4\u03b1 Design Patterns; \u03a4\u03b1 (Design Patterns) &hellip; <\/p>\n<p><a class=\"more-link btn\" href=\"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/2024\/11\/19\/java-design-patterns\/\">Continue reading<\/a><\/p>\n","protected":false},"author":55501,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-4","post","type-post","status-publish","format-standard","hentry","category-java-design-patterns","item-wrap"],"_links":{"self":[{"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/posts\/4","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/users\/55501"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/comments?post=4"}],"version-history":[{"count":0,"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/posts\/4\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/media?parent=4"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/categories?post=4"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.e-me-4all.eu\/PanosFotein\/wp-json\/wp\/v2\/tags?post=4"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}