编写高效优雅的java程序

朴灿烈づ我的快乐病毒、 2022-12-20 02:00 148阅读 0赞

## 1、构造器参数太多 ##

推荐使用建造者模式

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70][]

## 2.不需要实例化的类应该构造器私有 ##

例如，我们平时写的工具类，可以建一个私有的构造器，可以防止工具类被实例化。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 1][]

## 3.不要创建不必要的对象 ##

例如下方代码

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 2][]

![20201109152947145.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 3][]

![20201109153036210.png][]

说明：这里面有一个封装对象装箱的知识点，才导致需要花的时间变长了。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 4][]

## 4.避免使用终极方法 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 5][]

说明：不要使用Object提供的finalize方法来释放资源。

## 5.使类和成员的访问性最小化 ##

## 6.使可变性最小化 ##

## 7.优先使用复合胜过基继承 ##

下面是正常开发中，使用继承出现的问题。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 6][]

![20201109155125551.png][]

**打印计算出了6个元素。**

原因在于所继承的HashSet中addAll方法也调用了add方法，导致出现了3个元素，计算出6个元素的原因。代码截图如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 7][]

复合方式如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 8][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 9][]

![2020110916004184.png][]

## 8.接口优于抽象类 ##

## 9.可变参数谨慎使用 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4Mzc3MTkw_size_16_color_FFFFFF_t_70 10][]

如果是固定传参，就需要单独写出来。

## 10.返回零长度的数组或是集合，不要返回null ##

jdk已经为我们提供了，静态方法。

**Collections.EMPTY\_LIST**

**ArrayUtils.EMPTY\_INT\_ARRAY**

## **11.优先使用标准的异常** ##

![20201109163506423.png][]

虽然现在很多人都喜欢自定义异常类，使用jdk提供的异常类，追求代码的重用。

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[20201109155125551.png]: https://img-blog.csdnimg.cn/20201109155125551.png
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