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Hello team.

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Today we will discuss what are variable length arguments in Java.

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Let's start from the problem statement.

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You want to create method, but you don't know how much arguments will be passed to that method.

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There can be different business cases, but let's simplify and pretend that you need to create method

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which will some numbers, but you don't know how much numbers will be passed to this method.

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To not create method which returns sum of two numbers, and another method which returns sum of three

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numbers, and so on, you create one method with variable length arguments.

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The syntax is simple.

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You need to specify type of arguments, right?

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Ellipses and variable name.

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Inside the method you can treat this variable as array.

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This syntax will allow you to pass different amount of arguments to the method.

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Here you can see that I pass five integers and here I pass just one argument.

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In both cases this method is called and result is returned.

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You can even change the way how you declare a main method instead of specifying that the main method

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takes an array of strings, we can say that the main method can work with variable length arguments

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of type string declaration like this is also possible.

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Important thing to flag here is that variable length arguments should be declared as last parameter

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in the method.

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For example, this method declaration will produce compilation error because the variable argument type

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int of the method must be the last parameter.

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Because during runtime, JVM should know when int arguments are finished and strings are started, and

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when we adjusted the method declaration, everything is fine and there is no compilation error.

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Variable length argument always should be declared as the last parameter in the method.

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You already saw real life example of variable length argument, but probably didn't pay enough attention.

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Do you remember lesson about string formatting?

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Method format takes variable length arguments as a parameter, because we never know how much format

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specifiers will be present in string, which we need to format.

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That's all what I wanted to share with you regarding variable length arguments.

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Now let's recap what you have learned about methods in this section.

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You learned how to declare and call methods.

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You understand what method signature is and how we can overload methods.

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Now you understand that both reference and primitive types of data in Java are passed by values.

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During the method invocation, we wrote recursive methods and learn what variable length arguments are.

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Let's take a look at your homework now.

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Your homework primarily consists of coding exercises.

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Now when you know how to write custom methods, how to use loops, arrays, and primitive types of data,

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our tasks might become a little more complicated.

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I tried to describe homework with as much details as I could.

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Try to solve these tasks.

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I will share with you source code of the solution for these tasks, but try to solve them by yourself

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first.

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Thanks a lot for your attention and see you in the next lesson.