How is data passed to method parameters in Java?

In Java, data is passed to method parameters by value (pass-by-value). For primitive types (int, boolean, etc.), a copy of the value is passed to the method. For objects, a copy of the reference to the object is passed, meaning the object itself is not copied, but the reference to it is passed by value.

Example:

void changeValue(int x) {
    x = 10; // local copy is changed
}

void changeObject(MyObject obj) {
    obj.field = 10; // the field of the object referenced is changed
}

Thus, changes to primitive parameters inside the method do not affect the original variables, but changes to object fields do, since the object is the same.