LintCode_204 Singleton

原创于 2016-08-04 04:21:53 发布 · 231 阅读

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本文介绍了一种常用的设计模式——单例模式，并通过具体实例演示了如何在类中实现getInstance方法，确保每次调用该方法都能返回同一个实例。

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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();

定义一个静态变量来解决：

class Solution {
public:
    /**
     * @return: The same instance of this class every time
     */
    static Solution* instance;
    static Solution* getInstance() {
        if (instance == NULL) {
            instance = new Solution();
        }
        return instance;
    }
};

Solution* Solution::instance = NULL;