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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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| 10 |
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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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| 40 |
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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. |
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