Benefits of Polymorphism So to help solidify the concept, let’s look at yet another example. Let’s imagine that we’re part of a very large software team and we’ve all been tasked with developing an accounting system and this is for an It company. So one of the things that we’re going to have to know about in the system are the different kinds of employees. And so for our system we really have three different the kinds of employees. We have managers, instructors and programmers. So we come up with…

Section Overview All right, continuing on with the concepts of object oriented programming, and this time we’re going to hit the topic of polymorphism. Polymorphism is all about substitutability and it gives us a way to make our applications futureproof in a way and flexible. It is a tough concept, just to be honest, and so we’re going to spend quite a bit of time going over it. By the end, you’ll be ready to work with Polymorphism. Polymorphism Demo Polyamorphism has a pretty rough reputation in regards to how…

Section Overview We’re going to add a little bit to our concept and understanding of collections. We’re going to talk about generics and we’re also going to talk about how to sort and search through our collections. Limitations of Collections So I think you’ll probably agree that collections are much, much easier to use than an array if you don’t really know what size you’re going to be working with or if that size is going to grow or shrink over time. And that’s what’s great about collections. They can…

Section Overview In this section, we’re going to learn about a new construct that was added to Java eight. It’s called the lambda. And the lambda gives us a way to pass in a block of code to a method as a parameter. We’ll also talk about static imports. So let’s hit the first lecture and look at lambda’s. Marker and Functional Interfaces In the previous section, you learned all about interfaces, you learned all of the syntax and the rules. And we really don’t have a lot to add…

Section Overview In this section, we’re going to talk about how do we write code to handle situations. That where things might not go as according to plan. Give you an example. You’re running a program. It connects to the database, but the database is down. How do you prepare for that in your code? Well, Java gives us something called exception handling. And that’s the concept we’re going to learn in this section. Throwable Whenever we write a program, we really hope that everything is going to go according…

Section Overview In this section, we’re going to look at another new API that was added to Java Eight. It’s called the Java Time Library and it’s going to give us classes to work with what it sounds like time, time and date. So we’ll look at local date, local date time, local time, and another class called period. So let’s start working with dates. LocalDate Java Eight gave us a brand new set of classes to work with for dealing with dates and times and durations. And they replaced…

Sets The next type of collection we’re going to look at is the set. And a set is another subtype of the collection interface. Now, the characteristics of a set is that no duplicate objects are allowed and so it’s going to use the equals method to determine whether or not an object is duplicate. Once again, another reason why you want to override equals. Generally speaking, the orders of the elements in a set are not maintained, although there is something called a tree set which will allow you…

Section Overview We’ve talked about the array and we saw that it’s a great way of creating collections of related objects together. But we saw that there were some limitations as well. So we’re going to look at something that’s a little bit more flexible. It’s called a collection. And so we’ll start right away talking about array lists and so on. Let’s start with lecture number one. When Arrays Are Not Enough When we code, we very frequently have to put together collections of things. We’ve seen that we…

Multi-Dimensional Arrays So far we’ve been looking at singledimensional arrays and that’s predominantly what you’re going to be using. Java does, however, support multidimensional arrays. The way that we create this is that each dimension will have its own set of square brackets. So here’s an example of creating a twodimensional array. Notice that we’ve got two sets of square brackets on the left side as well as two sets on the right. What we’re saying is this is a two dimensional array. Now the way that multi dimensional arrays…

Section Overview In this section, we’re going to begin our discussion about different kinds of collections. And we’re going to look at one of the most basic forms of collection, which is called an Array. So an Array is just a way for us to take a bunch of related things, put them all together and store them in memory, volatile memory. That is, memory that could be erased if the program shuts down. But while we’re working with our program, we’re going to need to access data. And this…