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We have situations, one, we have to do things repeatedly for that we have loops.

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All right.

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But we would like to run code based on different conditions, but we can use controls for that.

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And we use methods if we would like to wrap these into a block and reuse it for different purposes.

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To explain what methods are, I'm going to use an example that my math teacher gave me in primary school,

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maybe you have seen something similar.

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So we had imaginary machine in primary school.

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The machine had one input and one output.

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And we had to figure out what the machine does.

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For example, an input like five and we had an output 15.

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OK, so what the machine does, it wasn't obvious the time, but the machine multiplies the number that

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goes and by free and the result comes out.

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We also had exercises when the machine had two inputs and one output.

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Five and Fragos and 15 comes out.

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And the machine just simply multiplies the two numbers.

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The good thing about these machines is that they can be reused with other numbers and they can just

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do their job.

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In Java, you can have machines or methods that have a lot of inputs or machines that don't have an

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input or output, it just prints out a text two times or it has an input, but there is no output more

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than printing out something.

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By definition, a method or a function is a block of code, which only runs when it is called.

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Functions are one of the most important features of all programming languages.

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It is very important to understand them and use them the correct way.

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The takeaway from here is that a method is a block of code that runs only when it is called.

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They have inputs and outputs, if there is any.

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And their biggest advantage is that they are reusable.

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So what we are going to cover in this lecture, first, we are going to look into how to create a method,

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then how to call a method.

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After that, I will tell you more about parameters and arguments.

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What are the differences then?

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Return values.

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And finally, I will show you what the function overloading is and how to do that after this lecture.

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That will be according to.

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All right, let's do this.

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OK, so how we can define a method, first and foremost, it must be declared within a class, the most

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basic way to define a method is that to start with the day to type, that the function returns, then

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the function name next parentheses.

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After that, curly braces with a return statement.

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The returned values data type must match with the return type.

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The return type can be void, which means that the function doesn't return anything.

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In that case, we don't need the return statement, just like in the following example.

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This say good morning function simply prints out.

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Good morning.

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Function definition can be more complex than this, you can add more parameters to definition as modifiers

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can be public, private or package.

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We will cover these later in discourse.

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Static shows Javor that the function belongs to the class instead of an object.

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This is also a topic that I will tell you more after you will have knowledge and classes and objects.

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The return type and the function name have been mentioned previously.

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Parameters are optional, parameters are passed and can be used in the functions block.

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You have already used such functions.

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For example, the main method.

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The public is an access modifier, static shows that it belongs to the class well.

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It shows that it doesn't return a value made is the function name, then a parentheses string square

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brackets shows that it is an array of strings and it is named ARGs.

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Now, let's see a function that's a bit less complex, get 10 percent of discount price, takes an enterprise

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and multiply it by zero point nine and returns the result because we multiply a number by zero point

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nine, we will get a nonpoor number.

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So the return data type is double.

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One additional thing I would recommend you is that the function should do one thing and its name must

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tell what the function really does.

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To call a method in Java, right, the methods name first, followed by two parentheses with the parameters,

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if there is any, and a semicolon in the case of get ten percent of discount price, we can use directly

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twenty thousand as an input or we could use a variable name like Price.

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There are other ways to use it, like a sign the output or the return value to a variable, as you can

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see, the variables data type matches the functions return data type.

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You can also use the function as a parameter for any other functions, like, in our case, for Quintel

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and function.

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Now let's move on to parameters and arguments.

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Information can be passed to methods, true parameters, they are specified after the functions name

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inside the parentheses and separated with commas, parameters act as variables inside the methods.

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A method can have an unlimited amount of parameters, but I suggest you not to have more than three,

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the following example has a method that takes to end as parameters and returns the discount percentage

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of the price.

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Now, let's see what's the difference between parameters and arguments.

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We have a defined function here and a case where we call the function when a parameter is passed to

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the method and is called an argument.

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So from the example here and price is a parameter, while twenty thousand is an argument.

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Know that when you're working with multiple parameters, the method call must have the same number of

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arguments as there are parameters and the arguments must be passed in the same order.

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Moving on to return values, when you use a function to return a value, the return type must match

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with the data type of the value that return.

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That data type can be anything a primitive or an object.

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When your function doesn't return a value, the function must use void instead of a return type.

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Additionally, there is no return statement in the function like in the case of say good morning function.

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Our last topic is overloading with method, overloading, multiply methods can have the same name with

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different parameters.

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Why would we need that?

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Because we can have functions that do the same thing on different data types.

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And instead of using different names for the same purpose, we use overloading.

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OK, this go template for overloading may not make it clear.

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So move on to the examples.

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So here we have the same functions, same definition, same return statement, but the parameters are

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different with having just the end version.

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We couldn't use double or float values or we should convert them into an end by having a function with

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a double parameter.

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We can use decimal numbers with the same name based on the data type we pass to the function.

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Java will know which functions should be called.

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So that's it, I hope it was clear if it wasn't, I will try to make it more understandable in the coding

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part.