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强推！阿里p7大佬整理的这几款高效Java工具，网友：再也不加班了
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status)","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"退出虚拟机。exit(int)方法是终止当前正在运行的java虚拟机，参数是状态码。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"①该方法用于退出jvm，如果参数是0表示正常退出jvm，非0表示异常退出jvm。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"②退出jvm后，后面的代码就不会执行。无论传0还是传1，Jvm都会退出。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"③注意：0或者非0的数据都可以退出Jvm，对于用户而言没有任何区别，对于windows是有作用的，因为如果传非0对于windows而言是异常终止的，如果是正版的操作系统，对于异常退出的软件，需要把这些异常退出的软件信息做成报告发送给微软，微软就可以针对这些问题对系统做出一些修改。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"④我们程序员的编程习惯是：如果在try块中退出Jvm，try块里面是没有异常的代码，所以try块中要传0，如果是在catch块里面退出Jvm，我们习惯于用非0退出。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"三、Number 类","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"数据的基本数据类型有byte、int、short、long、double、float、boolean、char 等8种。但在实际的开发当中，我们有时候会遇到需要使用数字对象，而不是数据类型的情况。为解决这个问题，java为每一种数据类型，提供了相对应的类，即包装类，对应的包装类型也有八种：Byte、Integer、Short、Long、Double、Float、Boolean、Character。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"包装类型都是用final声明，不可以被继承重写。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"当数据类型需要被当做对象使用时，编译器会将数据类型转换为对应的包装类，这个过程被称为装箱；而当包装类对象被当做数据类型使用时，编译器会将包装类转换为对应的数据类型，这个过程被称为拆箱。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Number类是java.lang包下的一个抽象类，提供了将包装类型拆箱成基本类型的方法，所有基本数据类型（除 boolean 和 char）的包装类型都继承了该抽象类，并且是final声明不可继承改变。","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/81/814a25f391bcf4998f1ff8f354975b0d.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Number 的常用方法","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/3e/3e24ea585be8dff99fed2d97ab2db8f9.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"四、格式化","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Format 是一个用于格式化语言环境敏感的信息（如日期、消息和数字）的抽象基类。Format 定义了编程接口，用于将语言环境敏感的对象格式化为 String（使用 format 方法）和将 String 重新解析为对象（使用 parseObject 方法）。","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/a8/a8e89b56963e3183a5cc8a7201f30252.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}}],"text":"Java 平台为格式化日期、消息和数字分别提供了三个特殊的 Format 的子类：DateFormat、MessageFormat 和 NumberFormat。具体的子类必须实现三个方法：","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/1b/1b41b9a2e943a3b151efcb28423cd53b.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"1、DateFormat","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"DateFormat 是日期/时间格式化子类的抽象类，它以与语言无关的方式格式化并解析日期或时间。 SimpleDateFormat 是一个以与语言环境有关的方式来格式化和解析日期的具体类。它允许进行格式化（日期 -> 文本）、解析（文本 -> 日期）和规范化。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}},{"type":"strong","attrs":{}}],"text":"（1）日期和时间模式","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/24/2412cfe1a944dd2560648d2862a46fd8.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}},{"type":"strong","attrs":{}}],"text":"（2）同步","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"日期格式是不同步的。建议为每个线程创建独立的格式实例。如果多个线程同时访问一个格式，则它必须是外部同步的。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"2、NumberFormat","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}}],"text":"NumberFormat 是所有数值格式的抽象基类。此类提供格式化和解析数值的接口。NumberFormat 还提供了一些方法来确定哪些语言环境具有数值格式，以及它们的名称是什么。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}},{"type":"strong","attrs":{}}],"text":"（1）DecimalFormat","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"DecimalFormat 是 NumberFormat 的一个具体子类，用于格式化十进制数字。该类设计有各种功能，使其能够解析和格式化任意语言环境中的数，包括对西方语言、阿拉伯语和印度语数字的支持。它还支持不同类型的数，包括整数 (123)、定点数 (123.4)、科学记数法表示的数 (1.23E4)、百分数 (12%) 和金额 ($123)。所有这些内容都可以本地化。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}}],"text":"① 特殊模式字符","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}}],"text":"模式中的很多字符都是按字面解释的；在解析期间对其进行匹配，在格式化期间则不经改变地输出。","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/86/86984f48c93b600375e1c18d929eba34.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"② 舍入","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"DecimalFormat 提供 RoundingMode 中定义的舍入模式进行格式化。默认情况下，它使用 RoundingMode.HALF_EVEN。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"③ 同步","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"DecimalFormat 通常不是同步的。建议为每个线程创建独立的格式实例。如果多个线程同时访问某个格式，则必须保持外部同步。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"示例","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/cf/cf234c7bb01445f7e59f79ae3da9dfe3.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/be/be01235e58c26488d0f039182f37efcd.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}},{"type":"strong","attrs":{}}],"text":"（2）ChoiceFormat","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"ChoiceFormat 允许将格式应用到某个范围的数。它通常用于在 MessageFormat 中处理复数。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Choice 格式不是同步的。建议为每个线程创建单独的格式实例。如果多个线程并发访问一个格式，则它必须保持外部同步。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"3、MessageFormat","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"MessageFormat 提供了以与语言无关的方式生成连接消息的方式。使用此方法构造向终端用户显示的消息。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"MessageFormat 获取一组对象，格式化这些对象，然后将格式化后的字符串插入到模式中的适当位置。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#4D4D4D","name":"user"}}],"text":"示例：","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/f2/f26ecdf634263fb6930ad661bfbd2bc1.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"输出：The disk “MyDisk” contains 1,273 file(s).","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"注意：消息格式不是同步的。建议为每个线程创建独立的格式实例。如果多个线程同时访问一个格式，则它必须是外部同步的。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"五、随机数类","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"1、Random 类","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Random 的对象能够产生随机数，他可以产生随机整数、随机float、随机double，随机long。","attrs":{}}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/28/28cd169738344b10c205e6a6e5b550dc.jpeg","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"heading","attrs":{"align":null,"level":1},"content":[{"type":"text","text":"2、Math 类的 random() 方法","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Math 类的 random() 方法返回的数值是[0.0,1.0）的 double 型数值，可以对其进行运算和类型转换获得需要的随机数。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"获得某个范围的特定类型的随机数：( 数据类型 )( 最小值 + Math.random() * ( 最大值 - 最小值 + 1 ) )","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"int a = (int)(30 + Math.random() * 71) // 生成[30，100]的随机整数","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"小结","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"以上是目前整理的一部分内容，如果有遗漏的欢迎大家补充！","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"color","attrs":{"color":"#1F1F1F","name":"user"}}],"text":"今日份分享已结束，请大家多多包涵和指点！","attrs":{}}]}]}
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