How do I create a temporary file in Groovy?

You can use java.io.File.createTempFile() in your Groovy code.

def temp = File.createTempFile('temp', '.txt') 
temp.write('test')  
println temp.absolutePath

File.createTempFile("temp",".tmp").with {
    // Include the line below if you want the file to be automatically deleted when the 
    // JVM exits
    // deleteOnExit()

    write "Hello world"
    println absolutePath
}

Simplified Version

Someone commented that they couldn't figure out how to access the created File, so here's a simpler (but functionally identical) version of the code above.

File file = File.createTempFile("temp",".tmp")
// Include the line below if you want the file to be automatically deleted when the 
// JVM exits
// file.deleteOnExit()

file.write "Hello world"
println file.absolutePath