Joiner ，Strings，Splitter 用法

转载收藏 https://blog.csdn.net/qq_26562641/article/details/53665059
Guava
一．Strings
1．Strings.padEnd方法
//padEnd普全右
String a="12345";
String b=Strings.padEnd(a, 10, 'x');
System.out.println(b);
结果为：12345xxxxx
2．Strings.padStart方法
//padStart 普全左
String a="12345";
String b=Strings.padStart(a, 10, 'x');
System.out.println(b);
结果为：xxxxx12345
3．Strings.isNullOrEmpty 方法
//Strings.isNullOrEmpty 校验空值
String a="";
boolean b=Strings.isNullOrEmpty(a);
System.out.println(b);
结果为：true
4．Strings.nullToEmpty 方法
//Strings.nullToEmpty 如果为null 转为""
String a=null;
String b=Strings.nullToEmpty(a);
System.out.println(b);
结果为：
5．Strings.emptyToNull 方法
//Strings.emptyToNull 如果为"" 转为null
String a="";
String b=Strings.emptyToNull(a);
System.out.println(b);
结果为：null
6．Strings.repeat 方法
//Strings.repeat 重复字符串
String a="123";
String b=Strings.repeat(a, 3);
System.out.println(b);
结果为：123123123
7．Strings.commonPrefix 方法
//Strings.commonPrefix 获取a,b左公共部分字符串
String a="abcdsfsfs";
String b="abc3sfsd";
String c=Strings.commonPrefix(a, b);
System.out.println(c);
结果为：abc
8．Strings.commonSuffix 方法
//Strings.commonSuffix 获取a,b右公共部分字符串
String a="faaxyz";
String b="fwefxyz";
String c=Strings.commonSuffix(a, b);
System.out.println(c);
System.out.println(c);
结果为：xyz
二，Joiner 连接工具类
分析源码可知：该类构造方法被private修身，无法直接通过new实现
通过调用on传如分隔符来得到实例。
1．连接List列表
Joiner joiner = Joiner.on(",");
List<String> list =new ArrayList<String>();
list.add("xiaoming");
list.add("xiaohong");
list.add("wangsan");
System.out.println(joiner.join(list));
结果：xiaoming,xiaohong,wangsan
2．连接Iterator<T>列表
Joiner joiner = Joiner.on(",");
List<String> list =new ArrayList<String>();
list.add("xiaoming");
list.add("xiaohong");
list.add("wangsan");
Iterator<String> it=list.iterator();
System.out.println(joiner.join(it));
结果：xiaoming,xiaohong,wangsan
3．连接多个字符串
Joiner joiner = Joiner.on(",");
System.out.println(joiner.join("123","345","56","43"));
结果：123,345,56,43
4.连接字符串与列表
Joiner joiner = Joiner.on(",");
List<String> list =new ArrayList<String>();
list.add("xiaoming");
list.add("xiaohong");
list.add("wangsan");
StringBuilder builder=new StringBuilder("标题");
System.out.println(joiner.appendTo(builder,list));
结果：标题xiaoming,xiaohong,wangsan
5.跳过null值连接
Joiner joiner = Joiner.on(",").skipNulls();
List<String> list =new ArrayList<String>();
list.add("xiaoming");
list.add(null);
list.add("wangsan");
StringBuilder builder=new StringBuilder("标题");
System.out.println(joiner.appendTo(builder,list));
6.替换null值进行连接
Joiner joiner = Joiner.on(",").useForNull("123");//替换null为123
List<String> list =new ArrayList<String>();
list.add("xiaoming");
list.add(null);
list.add("wangsan");
StringBuilder builder=new StringBuilder("标题");
System.out.println(joiner.appendTo(builder,list));
结果：标题xiaoming,123,wangsan
三．Splitter 工具类
主要功能是拆分字符串为集合 Map等。
通过分析源码可知，该工具类同意通过 on函数传入拆分字符得到实例。
1．拆分字符串为List集合
Splitter splitter =Splitter.on(",");
String str="a,b,c,d,e,f,g";
List<String> list=splitter.splitToList(str);
System.out.println(list);
结果：[a, b, c, d, e, f, g]
2.忽略空字符
Splitter splitter =Splitter.on(",").omitEmptyStrings();
String str="a,b,c,d,,f,g";
List<String> list=splitter.splitToList(str);
System.out.println(list);
结果：[a, b, c, d, f, g]
3.忽略空字符且去除字符串前后空格
Splitter splitter =Splitter.on(",").omitEmptyStrings().trimResults();
String str="a,b,c,d,,f, g ";
List<String> list=splitter.splitToList(str);
System.out.println(list);
结果：[a, b, c, d, f, g]
HtmlEscapers工具类
将html转义如下源码所示
Escaper htmlEscaper =HtmlEscapers.htmlEscaper();
System.out.println(htmlEscaper.escape("<a>你好</a>"));
结果：<a>你好</a>

Joiner ，Strings，Splitter 用法

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