This section introduces classes, methods, and beans. Groovy classes are similar to Java classes declared with the class keyword. Usually, a class definition starts with the package name, and then import package statements. One key difference with the Java counterpart is that Groovy imports six packages and two classes by default. So, if you create any class, these packages and classes are automatically available to you:

import java.lang.* // this is the only default import in Java
import java.util.*
import java.io.*
import java.net.*
import groovy.lang.*
import groovy.util.*
import java.math.BigInteger
import java.math.BigDecimal

Classes and methods in Groovy by default have public access, whereas in Java it is set to package-private. We will start with a sample Groovy class:

class Order {
  int orderNo
  Customer orderedByCustomer
  String description

  static main(args) {
    Order order1 = new Order();
    order1.orderNo = 1;
    order1.orderedByCustomer = new...