class Person{
String firstName
String lastName
}

def p = new Person(firstName: 'Naresha', lastName: 'Bhat')
println p

The default behavior of toString is to print the class name followed by the object’s hash code.

 Person@7e3d3158

By applying the @ToString annotation, we can customize the toString behavior.

import groovy.transform.ToString

@ToString(includeNames=true)
class Person{
String firstName
String lastName

}

def p = new Person(firstName: 'Naresha', lastName: 'Bhat')
println p

This would output

Person(firstName:Naresha, lastName:Bhat)

For more details check http://groovy.codehaus.org/gapi/groovy/transform/ToString.html

public class TestClass{
  public static void main(String[] args){
    System.out.println("Hello World..!");
  }
}