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You can update the value inside a variable.

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You saw that defining a variable and storing a value is pretty simple.

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You need to write the type of value we can store, this variable in particular can only store integer

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values.

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You also need to write the variable name and the value that you want to store.

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So available stores information about your app, but as time passes, things change and you need to

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update that information.

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That's why in this video, you're going to learn to update the value inside a variable.

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First thing I need you to do is create a new class by yourself inside the section to project make a

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new file named Buster Java and then make sure the bus class has the main method.

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Take a couple of seconds to do that.

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All right, how do you update variables if you want to update a variable, it's fairly simple.

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Each have to set it equal to a new value and the value inside changes every time you update it.

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I prepared a fun example so that we can learn more about this, you, the Java prodigy, you found a

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job at the Ministry of Transportation in the ministry wants you to build a Java program, the programming

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you to print, how many passengers are inside a bus, and then you need to print the number of passengers

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at every stop.

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So I'm going to assume you ready set the class up and before we start our code, you'll notice that

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the terminal output is pretty cluttered.

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You could just close the terminal, open a new terminal, but that's pretty lame if you ask me.

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We can instead clear the terminal output by writing.

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Clear.

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Nice, this command is very useful, and I'm going to add it to your cheat sheet.

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OK, so the bus driver is starting his shift.

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He boarded the bus and naturally the bus is empty and he starts with zero passengers and passengers

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is equal to zero.

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Don't forget your semicolon.

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All right, his first stop is the river station, let's say there he picks up nine passengers.

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So we need to update the number of passengers by nine passengers.

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Is equal to passengers.

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Plus nine.

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Then after you update the number of passengers, you can print the new value system, dot out dot print

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line passengers.

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All right, compiling the code, Java Sea Bass Java and running it.

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Clearly now there are nine passengers in the second line, you said passengers equal to itself, zero

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plus nine, and now it stores a value of nine.

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Now the bus driver is approaching the Sugar Mountain sweetshop in, your passengers go crazy for sweets.

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So there he drops off five passengers.

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Once again, you need to update the number of passengers that is passengers is equal to passengers minus

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five.

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And after you update the value print system, dot, dot, dot, print line passengers.

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And using the up key, go ahead and compile the code.

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All right, we started with zero passengers.

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The bus driver picked up nine and dropped off five.

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So the pattern follows four subtraction, the computer sets the value of passengers equal to itself,

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nine minus five.

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Now, there are four passengers in the bus and let's say the last stop is the post office and they're

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the bus driver drops off the remaining passengers.

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So passengers equal to passengers minus four.

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And we're going to print the value system, dot, dot, dot, print line passengers.

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Recompile your code and run it.

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And everything works out as expected.

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Your application updates information at every stop.

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The bus starts with zero passengers, picks up nine.

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Drops out five.

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And drops the rest.

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This is a pretty common way of updating integer variables, but there is an easier way.

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And it's known as the plus equals operator, the plus equals operator updates a variable by adding the

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value on the right.

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So you can replace the first update with the plus equals operator passengers plus equals nine.

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And if you ask me, this looks a lot better.

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Let's see if it works.

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And indeed, it does.

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Passenger starts at zero and the plus equals operator updates the variable by adding nine fairly intuitive.

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Now, what about these updates?

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Well, there's also the minus equals operator.

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This one, as you'll probably guess, it's tracks the value on the rights.

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So you can replace the remaining updates with the minus equals operator.

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Recompile the code.

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And everything works as expected.

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In both cases, it appears the variable by subtracting the value on the right.

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And in this lesson, you learn to update the value inside a variable, you built a Java program that

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updates the number of passengers when the bus picks up or drops passengers off plus equals and minus

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equal to update the variable using the value on the right.

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And that is all.