How do I execute ant.java properly from gradle?

I'm trying to invoke a jar, but I don't see any output when I run the command without args, and when I do run with args, I get the following error:

[ant:java] The args attribute is deprecated. Please use nested arg elements.
[ant:java] Java Result: 1

How do I invoke ant.java in such a way that I see output and can pass arguments?

task compressJs(){
  ant.java(jar:"lib/yuicompressor-2.4.6.jar",fork:true,args:['js/file.js', '-o', 'build/js/file.js'])
}