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In this lecture, I'm going to talk about object references.

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This topic is divided into four parts.

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First, I will tell you what object references are.

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Second, what makes them different from primitives?

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Third, what basic built in object references Java has.

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And last, we will have a code in part about how we can use them.

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What object reference means, let me explain this, so object is an instance of a class, it is stored

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somewhere in the memory and reference is used to point to that memory location where that object is

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stored.

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You don't have to handle it.

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Jabot will do it for you and uses the variable name to get the object.

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To visualize this, you can see a class here.

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It is like a blueprint, a scheme, a plan for something like a car, a dodge challenger in our case.

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But it can be a movie, an RPG character or something else.

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So an object can be created based on that blueprint.

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Sticking to our example, we have a Dodge challenger because here it had a lot of attributes, like

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a number of seats, horsepower or is damaged.

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When you create an object, you can add value to all those attributes.

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You can have a dodge with three ninety two horsepower or another one with seven hundred and seven horsepower.

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But you can create many other objects with different attributes.

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You can create almost unlimited amount of objects out of a class.

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When you create an object, it is almost the same as with the primitives.

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So instead of data type, we use class name.

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Then variable name equals a value or the new keyword and the class name parentheses that where you can

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add some parameters to the class and a semicolon.

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As you can see, I used uppercase as a starter letter in case of class name.

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It is not forced by Java, but it is highly recommended, so it's almost a must.

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So as I mentioned, you can add parameters in the parentheses and based on that an object will be created.

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I will give you more details on this later in the classes lecture, so just to stick to the Dodge Challenger.

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We can create a class Dodge Challenger with all the attributes we coded in the previous lecture to create

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an object of deduction and your class, you have to do the following.

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The Challenger Red Dot challenger equals new Dodge challenger, and in the parentheses you add red and

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a semicolon.

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So it's going to create a dodge challenger.

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And the color of that car is going to be red, so based on this, you can create a green one as well.

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So don't change a green dot.

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Chinja, new dodge challenger green.

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So as you can see, the class name starts with uppercase.

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The variable name starts with a lowercase as in case of the primitives or any other variables.

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Right.

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Then it was a little bit of taste of classes and objects.

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Let's see what makes them different from primitives.

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The biggest difference is that they have functionality.

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So when we wanted to print something out, we used that printer and function and we put the text and

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the variables between the parentheses.

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In case of the challenger, we can create functionalities like honk and it would print something on

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the screen or get color, which would return the color of the car, or we can have it get a description

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or turn left or get horsepower.

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But the options are almost unlimited.

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What you have to keep in mind for now is that you can call these functions when you create an object

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and put a dot at the end of the variable name and you can use those functions that are available for

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that class.

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So, as I said, more on this later to let's see what built in data types Java has.

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They are pretty easy because every primitive has its object version with a little name change.

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So byte short integer instead of end long float, double boolean and character instead of char.

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The values you can store in them is the same.

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We also have a new one here.

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String String is for storing texts like Red Green Dot Chinja or sentence's.

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As I mentioned before, objects have useful functions in case of string to uppercase, to lowercase

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or equals that can be used to compare two strings or is empty or is blank.

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These functions are very good and used quite regularly, but be careful.

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The last two are not the same.

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Besides these, there are many other functions that can be used for strings.

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So to define a string variable, you have to do the following.

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So first the class name string, then car type is the variable name equals in parentheses.

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The text we would like to assign to car type variable name, then the semicolon.

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It's almost the same like with the primitives.

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Well string is a big topic.

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There will be a few other lectures to cover that we are going to do some coding exercise with it, but

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we will get back to it a bit later.

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OK, I know this lecture has a lot of more on this later part, but I wanted to give you some insight

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to those Java concepts.

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I think it is better to give some explanation now instead of not telling you anything or having a separate

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lecture with a ton of information moving back to object references.

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I think the best way we can see how they work, what they are, is to use them in the code.

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So let's get back to intelligent.