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Learn Java: Manipulating Variables
final Keyword

Throughout this lesson, we’ve discussed the different ways we can manipulate a variable; however, what do we do with a variable that should never change its value?

For example, the year we were born will always stay the same. There’s no way we can change that information. A value like this in our code should be unchangeable.

To declare a variable with a value that cannot be manipulated, we need to use the final keyword. To use the final keyword, prepend final to a variable declaration like so:

final int yearBorn = 1968;

When we declare a variable using final, the value cannot be changed; any attempts at doing so will cause an error to occur:

error: cannot assign a value to final variable yearBorn

Instructions

1.

Create an unchangeable double variable called pi and set its value to 3.14.

Print the value of pi.

2.

On a new line, try to change the value of pi.

What happens when the program is run?

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