cqc
Joiner
Joiner joiner = Joiner.on("; ").skipNulls();
return joiner.join("Harry", null, "Ron", "Hermione");
Joiner 实例是不可变对象，其每一次的配置都是返回一个新的对象，这个能保证其线程安全
Splitter
Splitter.on(',')
.trimResults()
.omitEmptyStrings()
.split("foo,bar,, qux");
工厂方法
Method | Description | Example |
Splitter.on(char) | Split on occurrences of a specific, individual character. | Splitter.on(';') |
Splitter.on(CharMatcher) | Split on occurrences of any character in some category. | Splitter.on(CharMatcher.BREAKING_WHITESPACE) Splitter.on(CharMatcher.anyOf(";,.")) |
Splitter.on(String) | Split on a literal String. | Splitter.on(", ") |
Splitter.on(Pattern) Splitter.onPattern(String) | Split on a regular expression. | Splitter.onPattern("\r?\n") |
Splitter.fixedLength(int) | Splits strings into substrings of the specified fixed length. The last piece can be smaller than length, but will never be empty. | Splitter.fixedLength(3) |
修饰方法
Method | Description | Example |
omitEmptyStrings() | Automatically omits empty strings from the result. | Splitter.on(',').omitEmptyStrings().split("a,,c,d") returns "a", "c", "d" |
trimResults() | Trims whitespace from the results; equivalent to trimResults(CharMatcher.WHITESPACE). | Splitter.on(',').trimResults().split("a, b, c, d") returns "a", "b", "c", "d" |
trimResults(CharMatcher) | Trims characters matching the specified CharMatcher from results. | Splitter.on(',').trimResults(CharMatcher.is('_')).split("_a ,_b_ ,c__") returns "a ", "b_ ", "c". |
limit(int) | Stops splitting after tjjhe specified number of strings have been returned. | Splitter.on(',').limit(3).split("a,b,c,d") returns "a", "b", "c,d" |
Splitter 实例是不可变对象，其每一次的配置都是返回一个新的对象，这个能保证其线程安全
CharMatcher
简单说，CharMatcher可以认为是一组字符组。
String noControl = CharMatcher.javaIsoControl().removeFrom(string); // 移除控制字符
String theDigits = CharMatcher.digit().retainFrom(string); // 仅保留数字
String spaced = CharMatcher.whitespace().trimAndCollapseFrom(string, ' '); // 将多个的空格或换行替换为一个空格， 也就是多行变一行
String noDigits = CharMatcher.javaDigit().replaceFrom(string, "*"); // 将所有数字替换为*
String lowerAndDigit = CharMatcher.javaDigit().or(CharMatcher.javaLowerCase()).retainFrom(string); // 保留数字或小写字母
内置的工厂方法
- any()
- none()
- whitespace()
- breakingWhitespace()
- invisible()
- digit()
- javaLetter()
- javaDigit()
- javaLetterOrDigit()
- javaIsoControl()
- javaLowerCase()
- javaUpperCase()
- ascii()
- singleWidth()
定制的CharMatcher生成方法
Method | Description |
anyOf(CharSequence) | Specify all the characters you wish matched. For example, CharMatcher.anyOf("aeiou") matches lowercase English vowels. |
is(char) | Specify exactly one character to match. |
inRange(char, char) | Specify a range of characters to match, e.g. CharMatcher.inRange('a', 'z'). |
negate() | 逻辑非 |
and(CharMatcher) | 逻辑与 |
or(CharMatcher) | 逻辑或 |
使用
Method | Description |
collapseFrom(CharSequence, char) | Replace each group of consecutive matched characters with the specified character. For example, WHITESPACE.collapseFrom(string, ' ') collapses whitespaces down to a single space. |
matchesAllOf(CharSequence) | Test if this matcher matches all characters in the sequence. For example, ASCII.matchesAllOf(string) tests if all characters in the string are ASCII. |
removeFrom(CharSequence) | Removes matching characters from the sequence. |
retainFrom(CharSequence) | Removes all non-matching characters from the sequence. |
trimFrom(CharSequence) | Removes leading and trailing matching characters. |
replaceFrom(CharSequence, CharSequence) | Replace matching characters with a given sequence. |
CaseFormat
一个简便的代码风格转换工具
CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, "CONSTANT_NAME")); // returns "constantName"
Format | Example |
LOWER_CAMEL | lowerCamel |
LOWER_HYPHEN | lower-hyphen |
LOWER_UNDERSCORE | lower_underscore |
UPPER_CAMEL | UpperCamel |
UPPER_UNDERSCORE | UPPER_UNDERSCORE |