We used a class similar to this in a previous exercise but I think it's a short and sweet example of what we need to review in this exercise.
Create An Account Class
create a property of type BigDecimal called balance with an initial value of 0.0
Create a method called deposit
use a conditional structure (if would work great here) to check if the amount being passed is less than zero. If it is we should catch this case because we don't want to deposit negative numbers. In this case, throw an exception.
Create another method called deposit that takes a list of amounts
use a for loop to loop over these amounts and call deposit
Now that we have our class let's test it out. You can do all of this in the same file (just don't create a file called Account.groovy)
Create an instance of the account class
deposit a valid amount
deposit an invalid amount (what happens?)
try / catch on invalid amounts
deposit a list of amounts.
//CODE
class Account {
BigDecimal balance=0.0
def deposit(BigDecimal amount)
{
if(amount <0){
throw new Exception("Deposit amoubt must be greater than 0")
Locate the class groovy.lang.Closure and spend a few minutes looking through documentation.
Create a Method that accepts a closure as an argument
Create a closure that performs some action
Call the method and pass the closure to it.
Create a list and use them each to iterate over each item in the list and print it out
Hint - You can use the implicit it or use your own variable
Create a map of data and iterate over it using each method.
This method can take a closure that accepts 1 or 2 arguments.
Use 2 arguments and print out the key and value on each line.
Demonstrate the use of curry and try to come up with an example different from the one we used in the lecture.
Explore the GDK
In the following exercises we are going to explore the GDK to find some methods that take closures and learn how to use them. Hint - I would narrow your search to java.util.Collection, java.lang.Iterable & java.util.List
Search for the find and findAll methods.
What is the difference between the two?
Write some code to show how they both work.
Search for the any and every methods.
What is the difference between the two?
Write some code to show how they both work.
Search for the method groupBy that accepts a closure
If you are new to Java or Groovy the idea of an Enum might be new. An Enum is a collection of constant values. We can use this collection of constants to create ranges. I want you to do some reading up on enum's and create an enum for days of the week. ex Sunday, Monday, etc...
Create a range from that enum
Print the size of the Range
Use the contains method to see if Wednesday is in that Range
Print the from element of this range
Print the to element of this range
2)Lists
Create a list days (Sun - Sat)
Print out the list
Print the size of the list
Remove Saturday from the list
Add Saturday back by appending it to the list
Print out the Wednesday using its index
3)Maps
Create a map of days of the week
1: Sunday, 2:Monday, etc...
Print out the map
Print out the class name of the map
Print the size of the map
Is there a method that would easily print out all of the days (values)?
Without closures you may have to look at the Java API for LinkedHashMap