Java学习 day06

Dear 丶 2021-11-16 19:20 321阅读 0赞

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70][]

## 1 Date ##

1.1 【比较】Date、Data  
![20190729155616978.png][]  
1.2 【样例】  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 1][]  
1.3 日期格式转换器  
1.3.1 概述  
![20190729160347573.png][]  
1.3.2 【样例】  
![20190729174721922.png][]  
1.3.3 日历类（Calendar）  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 2][]

## 2 String ##

2.1 字符串的基础  
2.1.1 概述  
![20190729105312335.png][]  
2.1.2 分类  
![2019072910561594.png][]  
2.1.3 理解  
（1）可变与不可变说的是=号后面的实体，而不是=号前面的引用  
![20190729105528617.png][]  
（2）不可变字符串在内存中的位置，堆区中的一块特殊区域（可以理解为堆区中的一块常量区）  
![20190729105546596.png][]  
（3）可变字符串（StringBuffer/StringBuider）  
![20190729141606957.png][]  
2.1.4 【比较】字符串(=号、equals()方法)  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 3][]  
所以：字符串是否相等的比较应该使用equals()方法(s1.equals(s2))

2.2 不可变字符串的常用方法（String）  
2.2.1 判断  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 4][]  
2.2.2 转换  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 5][]  
2.2.3 替换  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 6][]  
2.2.4 切割  
![20190729173143999.png][]

2.3 可变字符串的常用方法  
2.3.1 存储  
![20190729173431577.png][]  
2.3.2 删除  
![20190729173513849.png][]  
2.3.3 修改  
![2019072917355911.png][]  
2.3.4 获取  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 7][]  
2.3.5 反转  
![20190729173827954.png][]

## 3 正则表达式 ##

3.1 【样例】  
![20190729163055406.png][]  
![201907291631160.png][]  
\\d 表示数字  
3.2 使用  
3.2.1 匹配  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 8][]  
3.2.2 切割  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 9][]  
3.2.3 替换  
![20190729175340976.png][]  
3.2.4 获取  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 10][]

## 4 网址 ##

![20190729145208724.png][]  
服务器  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 11][]  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 12][]

## 5 修饰词（private、default(friendly)、protected、public） ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 13][]

## 6 Arrays ##

6.1 概述：数组工具类，内部封装了大量操作数组的方法–方法都是静态的

6.2 【样例】  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JsZXNzaW5nWFJZ_size_16_color_FFFFFF_t_70 14][]

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