10 - Methods in Java/001 Methods in Java Overview_en.srt

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Hello team!

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In this section we will learn with you more about methods in Java.

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We are going to have multiple lessons in this section from which you will learn what is method and what

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is method signature, how to declare methods and how to use them.

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You will understand how methods can return values.

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I will explain you how data is passed in Java by value and not by reference.

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How to write recursive methods and what are variable length arguments?

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Let's start.

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What is method?

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A method is a block of code which is referred to by name, and can be called at any point in your program

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simply with the methods name.

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Think of a method as a chunk of code, which can be performed on the request.

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When during the program execution method call is performed, the program proceed execution from that

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method and when method is finished, execution returns to the line of code in your program from where

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method was called.

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Let's write method together.

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Each method has access modifier.

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We will learn them during the object oriented programming topic.

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Let's write private.

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As of now, this means that we can access this method only in scope of this class.

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After that, let's write static.

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Static keyword means that this method is connected not with instances of this class, but with class

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itself.

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We'll have separate lessons where we will take a look at what a static and non-static methods.

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While we don't know OOP.

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Let's create static methods.

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Here we specify method return type.

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Each method can return some value after it finished.

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The result of the method execution can be assigned to variable of the same type as return type.

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And here is method name.

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Method names are usually verbs started with lowercase letter and written in camel case like this one,

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for example.

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It is very important how you name your methods.

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For example, guess what does this method do?

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It is straight and clear what this method does.

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You can save a lot of time for your colleagues and a lot of money for your company.

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Who pays for time of your colleagues if you will write clean code?

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Understanding of code which was written not by you can take up to 50% of time dedicated for development.

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That's why in this and in future lessons, I will put stress on clean code design.

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Because clean code is something that you can't learn in one day after you learned programming.

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It is something that you should learn constantly.

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After we wrote Methodname, we need to specify method parameters.

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Here we declare that this method can work with two integers, and int values can be passed as arguments

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to this method.

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Method name and method parameters together is called method signature.

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Why return type or access modifier is not part of method signature?

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The reason for this emphasis on just the method name and parameter list is because of overloading.

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What is overloading?

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Overloading it is the ability to write methods that have the same name but accept different arguments.

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The Java compiler is able to discern the difference between the methods through their method signatures.

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For example, we have method sum which can sum two arguments.

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This method can sum two integers and this method can sum to doubles.

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We can say that method sum is overloaded because we have two methods with the same name, but with different

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signatures.

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After we declared parameters, we should put braces.

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This will be our method body which will be executed each time we will call method.

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If method has return type, we should return some value from the method.

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To return value from the method, we need to write return keyword and specify either variable name or

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expression which has compatible type with the one specified in method declaration.

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It can be that method returns nothing.

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For example, here are methods which just prints values to console.

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They should return nothing because they just print values to console.

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In this case you should specify void as return type like this.

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And here you can find examples of the method invocations I call method some and it returns value.

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So I can initialize this int variable with the value which was returned from this method.

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Is it clear?

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I can call method and can pass to it the result of execution of another method like this.

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That means that this method will be executed first, and after that this method will be executed with

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value, which was returned from some method.

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You can find that printer console is also overloaded method which works with different types string,

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double and int.

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That's all.

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Thanks a lot for your attention.

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See you in the next lesson.

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Us.