Chapter 2. Creating and Destroying Objects 第二章節 建立和銷燬物件
THIS chapter concerns creating and destroying objects: when and how to create them, when and how to avoid creating them, how to ensure they are destroyed in a timely manner, and how to manage any cleanup actions that must precede their destruction.
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這章節關注建立和銷燬獨享：何時以及如何去建立他們，何時以及如何去避免建立他們，如何確保他們及時得被銷燬，以及如果管理在銷燬他們之前必須進行的清理行動。Item 1: Consider static factory methods instead of constructors 考慮靜態工程函式取代建構函式
The traditional way for a class to allow a client to obtain an instance is to provide a public constructor. There is another technique that should be a part of every programmer’s toolkit. A class can provide a public static factory method, which is simply a static method that returns an instance of the class. Here’s a simple example from Boolean
boolean primitive value into a Boolean object reference:
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類允許客戶端獲取例項的傳統方法是提供一個公共建構函式。還有另一種技巧就是成為每個程式工具包的一部分。一個類可以提供一個公共靜態工廠方法，它只是一個返回類例項的靜態方法。下面是一個簡單例子就是`Boolean`（`boolean`的簡單的裝箱類）。這個函式將`boolean`原始值轉化為`Boolean`物件引用：public static Boolean valueOf(boolean b) { return b ? Boolean.TRUE : Boolean.FALSE; }
Note that a static factory method is not the same as the Factory Method pattern from Design Patterns [Gamma95]. The static factory method described in this item has no direct equivalent in Design Patterns.