Lesson 8 | Other modifiers |
Objective | Introduce and explain the other modifiers supported by Java. |
Java - Non Access Modifiers
Abstract
The abstract
modifier identifies abstract
classes and methods. Abstract classes declare abstract
methods and defer the implementation of these methods to their subclasses. When an abstract
method is declared, its body is replaced by a semicolon.
Final
The final
modifier is used with classes, field variables, local variables, methods, and method parameters.
It indicates that an item may not be changed. A final
class may not be subclassed. A final
variable or parameter may not have its value changed (once it has been initialized). A final
method may not be overridden.
Native
The native
modifier identifies a native
method. Native methods are written in languages other than Java and executed outside the Java virtual machine. The body of a native method is replaced by a semicolon when it is declared. Native methods may not be abstract
.
Static
The static modifier identifies a variable or method that applies to a class as a whole rather than to specific instances of a class. Static
variables are shared by all class instances.
Static methods are
invoked on the class
in which they are declared, as well as on instances of a class. Static inner classes are covered in Module 3.
Synchronized
The synchronized
modifier identifies synchronized
methods and synchronized
statements.
Transient
The transient
modifier identifies a variable that may not be serialized. A transient
variable may not be declared as final
or static
.
Volatile
The volatile
modifier is used to indicate that a variable may be modified asynchronously in a multiprocessor environment.