How to call getClass() from a static method in Java?
As for the code example in the question, the standard solution is to reference the class explicitly by its name, and it is even possible to do without getClassLoader()
call:
class MyClass {
public static void startMusic() {
URL songPath = MyClass.class.getResource("background.midi");
}
}
This approach still has a back side that it is not very safe against copy/paste errors in case you need to replicate this code to a number of similar classes.
And as for the exact question in the headline, there is a trick posted in the adjacent thread:
Class currentClass = new Object() { }.getClass().getEnclosingClass();
It uses a nested anonymous Object
subclass to get hold of the execution context. This trick has a benefit of being copy/paste safe...
Caution when using this in a Base Class that other classes inherit from:
It is also worth noting that if this snippet is shaped as a static method of some base class then currentClass
value will always be a reference to that base class rather than to any subclass that may be using that method.
In Java7+ you can do this in static methods/fields:
MethodHandles.lookup().lookupClass()
The Answer
Just use TheClassName.class
instead of getClass()
.
Declaring Loggers
Since this gets so much attention for a specific usecase--to provide an easy way to insert log declarations--I thought I'd add my thoughts on that. Log frameworks often expect the log to be constrained to a certain context, say a fully-qualified class name. So they are not copy-pastable without modification. Suggestions for paste-safe log declarations are provided in other answers, but they have downsides such as inflating bytecode or adding runtime introspection. I don't recommend these. Copy-paste is an editor concern, so an editor solution is most appropriate.
In IntelliJ, I recommend adding a Live Template:
- Use "log" as the abbreviation
- Use
private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger($CLASS$.class);
as the template text. - Click Edit Variables and add CLASS using the expression
className()
- Check the boxes to reformat and shorten FQ names.
- Change the context to Java: declaration.
Now if you type log<tab>
it'll automatically expand to
private static final Logger logger = LoggerFactory.getLogger(ClassName.class);
And automatically reformat and optimize the imports for you.