Groovy支持兩種類型字符串：一般的Java字符串，它是java.lang.String的實例；和GStrings，它是 groovy.lang.GString的實例，並且允許文本中包含占位符。GStrings並不是String的子類，因為String 類是最終類（final class）不能被繼承。然而，GString與一般的字符串一樣，因為Groovy能將 GStrings轉型為Java strings。
GString 適用於編寫模板代碼（templating），因為您必須動態構建字符串（GStrings are useful in templating situations where you have to build your string dynamicly）。以下的清單給出了 一個例子。
使用GStrings：
firstWord = 'Hello'
secondWord = 'dlroW'
println "$firstWord ${secondWord.reverse()}"
結果如下：
Hello World
GStrings不同於Java strings在於它們允許以${..}的語法嵌入變量。如果一個字符串由雙引號或三 重引號括起來，並且包含一個非轉義符（unescaped）$，它必定是groovy.lang.GString的一個實例；否 則，就是java.lang.String的一個實例。
${..}裡可以包含任意有效的Groovy表達式，包括方法調用或變量名。只有調用GString的toString方 法時（例如，把結果輸出到控制台），${..}表達式才被求值。
Groovy支持的另一種字符串便是java.lang.String。然而，GDK還是動態注入許多幫助方法，使其易 於應用。
以下的例子展示了在Groovy中聲明一個字符串的不同方式：
s1 = "Hello \"World\" " //Escape double quotes，轉義雙引號
s2 = 'Hello "World" '
assert s1 == s2
s3 = 'Hello \'World\' ' //Escape single quotes，轉義單引號
s4 = "Hello 'World' "
assert s3 == s4
assert new String('Hello World') == "Hello World"
def s = ['h','e','l','l','o'] as char[]
assert new String(s) == 'hello'
assert new String(s,0,4) == 'hell'
s.eachWithIndex{ch,index -> assert ch == s[index]}
assert 'hello'.toCharArray() == ['h','e','l','l','o']
常用的轉義符：
assert '\t' == '\011' //Tab，Tab鍵
assert '\n' == '\012' //New line，換行符
assert '\r' == '\015' //Carriage return，回車
assert '\n' == """
""" //Spanning multiple lines，跨越多行
對象的字符串表示：
def object = new Object()
assert String.valueOf(object) == object.toString() //Objects
assert String.valueOf(true) == true.toString() //Booleans
assert String.valueOf('a') == 'a'.toString() //Characters
assert String.valueOf(1) == 1.toString() //Numbers
assert String.valueOf([a:1,b:2]) == [a:1,b:2].toString() //Collections
字符串長度：
s = "Hello World"
assert s.size() == 11
assert s.size() == s.length()
填充（pad）字符串：
assert 'Hello'.padRight(7,'*') == 'Hello**'
assert 'Hello'.padLeft(7,'*') == '**Hello'
assert 'Hello'.center(9,'*') == '**Hello**'
分解字符串：
s = "The quick brown fox jumps over the lazy dog"
assert s.tokenize() == ['The','quick','brown','fox','jumps','over','the','lazy','dog']
assert s.tokenize() == new StringTokenizer(s).collect{it}
s1 = "The,quick*brown*fox,*jumps*over*the*lazy*dog"
assert s1.tokenize(',*') == s.tokenize()
查詢字符串：
alphabets = new String('a' .. 'z' as char[])
assert alphabets.find{it >
'f'} == 'g' //First one found
assert alphabets.findAll{it > 'f'} == 'g'
.. 'z'//ALl found
assert alphabets.findIndexOf{ it > 'f'} ==
alphabets.indexOf('g')
assert alphabets.every {it > 'A'}
assert
alphabets.any{it < 'c'}
assert alphabets.startsWith('abc')
assert
alphabets.endsWith('xyz')
assert alphabets.contains('def')
assert
alphabets.indexOf('c') == 2
assert alphabets.indexOf('d') == alphabets.lastIndexOf
('d')
assert alphabets.count('a') == 1
替換字符串：
s = "Hello"
assert s.replace('H','Y') == 'Yello'
assert s.replace('l','p') == 'Heppo'
字符串反轉：
s = 'mirror'
assert s.reverse() == 'rorrim'
字符串操作符：
assert 'hello' + ' world' - 'l' == 'helo world' //Subtracts at most one l
assert ('Today is Sunday' - 'Sunday').trim() == 'Today is'
assert 'hello ' * 2 == 'hello hello '
def empty = []
assert 'abc'.each{empty << it} == 'abc'
assert 'abc'.next() == 'abd'
assert 'abc'.previous() == 'abb'
下標操作符：
assert 'hello'[1] == 'e'
assert 'hello'[2..'hello'.size() - 1] == 'llo'
assert 'hello'[0,2,4] == 'hlo'
assert 'hello'[-4,-2] == 'el'
字符串比較：
assert 'a' < 'b'
assert 'a' > 'A'
assert 'a'.compareTo('b') == - 1
assert 'a'.compareToIgnoreCase('A') == 0
尋找最大值和最小值：
Collections.max('abcdeF'.toList()) == 'e'
assert Collections.max
('abcdeF'.toList(), String.CASE_INSENSITIVE_ORDER) == 'F'
assert Collections.min
(['abc','abd','abe']) == 'abc'
assert Collections.min(['Abc','aBd','abE'],
String.CASE_INSENSITIVE_ORDER) == 'Abc'
StringBuffers和StringBuilders是可變的，允許字符串改變。StringBuilder不是線程安全的，因此 處理速度要比StringBuffers快。
def sb = new StringBuffer('Hello World')
assert sb.toString() == 'Hello
World'
sb.length = 5
assert sb.toString() == 'Hello'
assert sb.substring
(0,2) == 'He'
//Use <<, append(String) or leftShift(String) to append to
a StringBuffer.
//Using + to append to a StringBuffer will return a
String
sb = new StringBuffer("Hello")
assert sb + ' World' in
java.lang.String
assert sb << ' World' in java.lang.StringBuffer
assert sb.toString() == ("Hello World")
assert sb.append(", Groovy
rocks").toString() == "Hello World, Groovy rocks"
assert sb.leftShift(".
Doesn't?").toString() == "Hello World, Groovy rocks. Doesn't?"
您也可以對StringBuffer或StringBuilder使用下標，如：
sb = new StringBuffer("abcdefg")
assert sb[0] == 'a'
assert sb[2..4] ==
'cde'
assert sb[0].class == String
assert sb[-6..-4] == "bcd"
sb[0..2] =
"xyz"
assert sb.toString() == "xyzdefg"
操作StringBuffers：
sb = new StringBuffer("StringBuffers are mutable")
sb.delete(sb.indexOf(" are
mutable"),sb.size())
assert sb.toString() == "StringBuffers"
sb.insert(sb.size
(), " are mutable")
assert sb.toString() == "StringBuffers are
mutable"
sb.replace(sb.indexOf("StringBuffers"), "StringBuffers".size(),
"StringBuilders")
assert sb.toString() == "StringBuilders are mutable"
def
string = new String(sb)
def string2 = string.replaceAll("StringBuilders",
"StringBuffers")
assert string2 == "StringBuffers are mutable"
正如您看到的，GDK在java.lang.String，java.lang.StringBuffer和java.lang.StringBuilder基礎 上添加了很多實用的方法。前面的例子只討論部分方法，因此推薦您查看String的API文檔， http://groovy.codehaus.org/groovy-jdk/java/lang/String.html；StringBuffer, http://groovy.codehaus.org/groovy-jdk/java/lang/StringBuffer.html; StringBuilder, http://groovy.codehaus.org/groovy-jdk/java/lang/StringBuilder.html。
