Original IntelliJ Cast

Let’s talk about type casts — those things you hardly can avoid in JVM-based code. Being a helpful IDE, IntelliJ IDEA now does all the casting stuff for you when you are using its code completion in Java and Groovy.

To get you started, have a look at this Groovy example. In a dynamic language there’s almost no need in type casting at all — you just invoke any method on any object and hope it won’t fail. IDE can help you here, suggesting a list of acceptable choices based on preceding type checks:

In Java, there’s always a need in explicit casting. It’s easy of course, when you know the type to cast expression to. Smart completion after opening parenthesis has been able to do this for ages:

Imagine you’ve just checked an expression type via instanceof and now you want to invoke a method on the cast expression. Quite a natural wish, isn’t it? A week ago you had to write a cast manually, use a light bulb intention action or inst live template. Now you just invoke code completion after the cast expression and it suggests the members of the cast type. A lot simpler, right? Of course, the cast will be inserted automatically:

This works for both basic (Ctrl+Space) and smart completion (Ctrl+Shift+Space). I’ve been using this feature for 2 days now and I already can’t understand how could I survive without it through all the previous years.

Impressed already? But, there’s more. Say you’ve just checked that a certain expression has certain type. Then, you may want to cast that expression and assign the result to a variable, or pass it to a method. All you need is smart completion:

Moreover, as you know, IntelliJ IDEA has second smart completion feature. It’s now also aware of the run-time type checks that you made. After such a check you can perform cast and method invocation in a single action! Well, actually, you have to press Ctrl+Shift+Space two times, but that still counts:


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