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You can return values from a function.

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It's bad practice for your function to handle the final results.

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But it's good practice for your function to return the final results.

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Your function is going to return the area.

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Start by creating a new file called Return Values Dot Java and make sure that the class has a main method.

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First thing we'll do is just copy all the code from earlier and to return values.

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Java.

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We currently have a problem in that.

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Our function here is performing two tasks.

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It performs the task of calculating an area, and it also performs another task of printing that same

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area.

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At this point we might as well call the function, calculate area and print it.

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Obviously, we're not going to do that.

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It is bad practice for your function to handle the final result.

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It should return the final result.

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So in step one, your function must define a return type.

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The return type specifies what type of value that your function will return.

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We expect to return a double, so the function's return type is going to be double.

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In step two, your function needs to return a value.

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The function calculate area returns the final result the area that it calculates.

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And the value that you return must always match the return type.

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The return type is double, so the value that the function returns needs to be a double.

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The function caller retains it holds on to the return value.

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First we're calling calculate area.

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When the function gets invoked, the first parameter stores the first value that was passed in.

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The second parameter stores.

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The second value that was passed in.

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The function uses the value inside of each parameter to perform its task.

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It calculates an area and then it returns it.

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The function call retains, it holds on to the value that was returned.

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And we can store the return value in a variable.

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If you want to store the area for three different rectangles, I can just call this function three times

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each time passing in a different set of arguments.

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If I call the function and pass in these values, the first parameter stores the first value that was

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passed in the second parameter stores, the second value that was passed in the function uses the value

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inside of each parameter to calculate an area.

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The function returns the final result.

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The function call holds on to the return value, which we can store inside of a variable.

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Every time I call the function, I can store the final result that it produces inside of a variable.

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Let's do this in code, starting with step one, in that your function must define a return type.

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The return type specifies what type of value this function will return.

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We expect to return a double, so the function's return type will be double.

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Step two is for your function to return a value.

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Your function should not be the one to handle the final result.

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So we're going to delete this print statement and instead what this function will do is return the final

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result, the area that it calculates.

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And the value that you return must always match the return type.

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The return type is a double, so the value that the function returns needs to be a double as well.

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And our area variable is a double.

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And step number three, the function caller retains it holds on to the return value.

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And the only way to confirm this is by visualizing the runtime.

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So let's put three breakpoints over here and press the debug button.

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Let's step inside of calculate area.

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The length that was passed in is 2.3.

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The width that was passed in is 3.6.

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As a result, we produce an area that equals 8.28.

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If I step over.

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And here we can see that our function call holds on to the value 8.28, and then we can store the double

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that it retains inside of a variable.

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So if we continue to the next breakpoint, now we're calling calculate area again, this time passing

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in arguments of 1.6 and 2.4.

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Each parameter store is a value that was passed in so length stores 1.6 width stores 2.4.

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And now we're using these values to calculate an area and here we're returning the area that the function

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produced.

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Upon doing so, this function call holds on to the return value of 3.84, which we can then store in

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a double variable.

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So let's do that right now.

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I'm going to stop the runtime.

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As we hover over calculate area, it tells you that it returns a double, which we can then store in

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a double variable.

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Double area one.

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Do the same thing throughout.

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All right.

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Re visualizing the runtime.

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Here we're calling calculate area passing in values of 2.3 and 3.6.

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Stepping inside of the function, we calculate an area based on the values that were passed in stepping

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inside even more.

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Here we're returning the area that was produced by our calculate area function.

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Stepping over the function call, calculate area holds on to the return value of 8.28, and then we're

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storing that return value inside of double area one.

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Continuing to the next breakpoint.

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Now area one equals 8.28 and every time we call this function, the final result that the function produces

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gets stored in a variable.

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So area two equals 3.84 and area three is going to equal 10.92.

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And now by pressing continue, since there are no other breakpoints, the runtime finishes.

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So you learned how to return a value from a function.

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When you call a function, it's going to use the value inside of each parameter to calculate an area.

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The function returns the final result.

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The function call holds on to the return value, which we can then store inside of a variable.

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Every time I call the function, I can store the final result in a variable.