What's the difference between ${foo} and #{bar}?

Question

What's the difference between ${foo} and #{bar} in string placeholders?

Answer 1

#{} is not a plain groovy construct, it's not evaluated.

def foo = 1
def bar = 2

println "${foo} and #{bar}"

returns

 1 and #{bar}

Answer 2

也许它与Ruby和/或Coffeescript自己的字符串插值混合在一起。

红宝石：

irb(main):001:0> a = "foo"
=> "foo"
irb(main):002:0> "this is a #{a}"
=> "this is a foo"

Coffeescript：

a = "coffee"
alert "i'd love some #{a}"

Groovy使用${}表示法，字符串需要使用双引号或三重双引号声明：

groovy:000> a = "bar"
===> bar
groovy:000> """to the $a"""
===> to the bar
groovy:000> "to the ${a}"
===> to the bar