difference between Local Variable and Instant Variable
Difference between local variable and instance variable
Instance variable is declared within a class but not within a method, while a local variable is declared within a method.
Instance variable get a default value, so if they are used before initializing them, then also they compile fine. But in the case of local variable in Java, local variable in Java do not get an initial value, so if you use them in your code without initializing them, then you will get a compile time exception.