Programming Groovy 2

2.11 Gotchas

We’ll see a number of nice Groovy capabilities throughout this book, but some “gotchas“ do exist, ranging from minor annoyances to potential surprises. In the following sections, we’ll explore a few of them.

Groovy’s == Is Equal to Java’s equals

​==​ and ​equals​ are a source of confusion in Java, and Groovy adds to the confusion. Groovy maps the ​==​ operator to the ​equals​ method in Java. What if we want to actually perform the reference equals (the original ​==​, that is)? We have to use ​is​ in Groovy for that. Let’s understand the difference via an example:

str1 = 'hello'
str2 = str1
str3 = new String('hello')
str4 = 'Hello'

println "str1 == str2: ${str1 == str2}"
println ...