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GeezerVison is showing github.com — leet-code/Java/Singleton.java at master · awangdev/leet-code Expand file tree/ Copy pathSingleton.javaMore file actions executable file ·63 lines (50 loc) · 1.38 KB / Copy pathSingleton.javaFile metadata and controlsexecutable file ·63 lines (50 loc) · 1.38 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 E 1525415182 tags: Design 让一个class 是 singleton ``` /* Singleton is a most widely used design pattern. If a class has and only has one instance at every moment, we call this design as singleton. For example, for class Mouse (not a animal mouse), we should design it in singleton. You job is to implement a getInstance method for given class, return the same instance of this class every time you call this method. Example In Java: A a = A.getInstance(); A b = A.getInstance(); a should equal to b. Challenge If we call getInstance concurrently, can you make sure your code could run correctly? Tags Expand LintCode Copyright OO Design */ class Solution { public static Solution instance = null; public static Solution getInstance() { if (instance == null) { instance = new Solution(); } return instance; } }; // Thread safe: class Solution { public static Solution solution = null; /** * @return: The same instance of this class every time */ public static Solution getInstance() { if (solution == null) { synchronized (Solution.class) { // Double check if (solution == null) { solution = new Solution(); } } } return solution; } }; ``` |
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