Modifiers

 

8. Modifiers

8.1. Access modifiers

There are three access modifiers keywords available in Java: * public * protected * private

There are four access levels: public,protected, default and private.

They define how the corresponding element is visible to other components.

If something is declared public, e.g., classes or methods can be freely created or called by other Java objects. If something is declared private, e.g., a method, it can only be accessed within the class in which it is declared.

The access levels protected and defaultare similar. A protected class can be accessed from the package and sub-classes outside the package, while adefault class can get accessed only via the same package.

The following table describes the visibility:

Table 1. Access Level

Modifier	Class	Package	Subclass	World
public	Y	Y	Y	Y
protected	Y	Y	Y	N
no modifier	Y	Y	N	N
private	Y	N	N	N

8.2. Other modifiers

final methods: cannot be overwritten in a subclass abstract method: no method body

synchronized method: thread safe, can be final and have any access control

native methods: platform dependent code, apply only to methods

strictfp: class or method