Question: 1. if you create an instance variable in a class, is the default value true or false until otherwise changed?
2. Is it good practice to have an instance variable as ex. true then change the value to false and use that variable throughout your class? Or is that something you should conceptually avoid in terms of using instance variables?

Answer: 
[JLS 4.12.5](http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.12.5)

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> * Each class variable, instance variable, or array component is initialized with a default value when it is created (§15.9, §15.10): 
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> 	+ For type `byte`, the default value is zero, that is, the value of `(byte)0`.
> 	+ For type `short`, the default value is zero, that is, the value of `(short)0`.
> 	+ For type `int`, the default value is zero, that is, `0`.
> 	+ For type `long`, the default value is zero, that is, `0L`.
> 	+ For type `float`, the default value is positive zero, that is, `0.0f`.
> 	+ For type `double`, the default value is positive zero, that is, `0.0d`.
> 	+ For type `char`, the default value is the null character, that is, `'\u0000'`.
> 	+ **For type `boolean`, the default value is `false`.**
> 	+ For all reference types (§4.3), the default value is `null`.
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> if you create an instance variable in a class, is the default value true or false until otherwise changed?
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If the member is primitive , then `false`. If it is a wrapper, then `null`

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> Is it good practice to have an instance variable as ex. true then change the value to false and use that variable throughout your class? Or is that something you should conceptually avoid in terms of using instance variables?
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Setting true or false will be depends on your class context. No issues with it at all.

For ex: You are creating an customer Object and having an instance memeber isActive. If your design allows that all customers by default active then yo are right.