Java中的变量类型？

Question

Sometimes I see methods that have a parameter like public method(ObjectName variable)

Does that mean this method only accepts ClassName 's objects? For example from another class?

it might be a simple question but I am used to seeing only int's , String s etc. as parameters. I guess some methods can accept instances of other classes? How does compiler know then that the class in the parameter is valid? Does it know it from imports?

Answer 1

Basically, yes to all your questions. Some methods accept instances of classes, both others or this class. Compiler knows by imports and the other classes in the package. If you have a more specific question put some code up.

Answer 2

The formal rules can be found at http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.12.2

Basically if a method accepts class A then it can also accept any subclass of A . A can be any class, BigInteger InputStream URL etc. If a method can accepts interface B then it will also accept any class that implements B .