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What is the purpose of having a private variable with the appropriate setter method?

When I have a setter method for a private variable in java, what is the purpose of making the variable private?

We have private variables to prevent the user from directly accessing the state of the instance. But sometimes we have the appropriate setter and getter methods for accessing and changing the state of a private variable. If so, why do we make the variable private? Instead, can we just have a public variable?

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The rationale is that you are hiding the implementation. When you call

setX(23);

your corresponding variable xis hidden from client classes and cannot be directly detected or modified.

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This is a simple example, so the number of wheels is directly related to the number of tires, so we can set this when you use the setter methods, and we also want to know when the car was last updated, basically it allows you to perform other tasks that depend on from changing a variable.

The reason you make the variable private is because you have to use setter methods when accessing the variable from outside the class.

Hope this helps.

Thanks, Will

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