Exercises2.md

Exercises

1. Encode and decode

   1. Create two strings, one for a username and one for a password. Concatenate them together, separated by a colon. Use a method from the Groovy JDK to convert the resulting String to a byte array. Then use the encodeBase64 method on byte array to create an encoded string.

   2. Decode the string by using the decodeBase64 method, and using the result as an argument to the String constructor. Use the split method to return the original username and password.

2. Sorting a list

   Create a class called Course, with a String attribute called name and an int attribute called days. Create a list of four course instances, where at least two have the same number of days. Sort the list by number of days. Then, sort the list by days, but when the days are equal, sort by name.

3. Operator overloading

   1. Create a class called Money with a double amount and a String currency (like USD or EUR). Implement a plus method that checks that the currencies are the same and, if so, returns a new Money instance with the sum of the amounts and the correct currency. Write a similar minus method.

   2. Write a MoneyTest class in Groovy that uses + and - and verifies that they work properly.