String Methods

Groovy strings have all of Java's String methods, plus many extras from the GDK (the Groovy Development Kit — Groovy's additions to Java classes).

def s = 'Hello, Groovy'

println s.size()              // same as length()
println s.toUpperCase()
println s.toLowerCase()
println s.contains('Groovy')
println s.startsWith('Hell')
println s.indexOf('o')
println s.replace('Hello', 'Goodbye')
println s.reverse()
println '  padded  '.trim()

13
HELLO, GROOVY
hello, groovy
true
true
4
Goodbye, Groovy
yvoorG ,olleH
padded

Indexing and slicing

def word = 'Groovy'
println word[0]
println word[-1]          // negative index counts from the end
println word[0..2]        // a range of characters
println word[-3..-1]
println word[0..<3]       // ..< excludes the end

G
y
Gro
ovy
Gro

Splitting and joining

def csv = 'red,green,,blue'
println csv.split(',')          // Java: keeps the empty item
println csv.tokenize(',')       // Groovy: drops empty items
println 'one two  three'.split()
println(['a', 'b', 'c'].join(' | '))

[red, green, , blue]
[red, green, blue]
[one, two, three]
a | b | c

split returns an array and takes a regex; tokenize returns a list and treats its argument as a set of separator characters.

Padding and formatting

println 'Name'.padRight(10, '.') + 'Score'.padLeft(6)
println 'Ada'.padRight(10, '.') + '42'.padLeft(6)
println 'Linus'.padRight(10, '.') + '7'.padLeft(6)
println 'Title'.center(15, '*')
println String.format('%-6s|%5.1f|', 'pi', 3.14159)
println 'groovy'.capitalize()

Name...... Score
Ada.......    42
Linus.....     7
*****Title*****
pi    |  3.1|
Groovy

Checking content

println '123'.isNumber()
println '12a'.isInteger()
println ''.isEmpty()
println '   '.isBlank()
println 'abc'.every { it in 'a'..'z' }
println 'banana'.count('a')

true
false
true
true
true
3

Strings are immutable: every method returns a new string and leaves the original unchanged.

Practice

Given ' the quick brown fox ', print it trimmed, with each word capitalized, joined by single spaces.

def text = '  the quick brown fox  '
println text.trim().tokenize(' ').collect { it.capitalize() }.join(' ')

The Quick Brown Fox