Monday, April 4, 2011

Java modifiers list with usage and meaning



Modifier Used on Meaning
abstract class

interface

method
Contains unimplemented methods and cannot be instantiated.
All interfaces are abstract. Optional in declarations

No body, only signature. The enclosing class is abstract
final class

method

field

variable
Cannot be subclassed

Cannot be overridden and dynamically looked up

Cannot change its value. static final fields are compile-time constants.

Cannot change its value.
native method Platform-dependent. No body, only signature
none(package) class

interface

member
Accessible only in its package

Accessible only in its package

Accessible only in its package
private member Accessible only in its class(which defines it).
protected member Accessible only within its package and its subclasses
public class

interface

member
Accessible anywhere

Accessible anywhere

Accessible anywhere its class is.
strictfp class

method
All methods in the class are implicitly strictfp.

All floating-point computation done is strictly conforms to the IEEE 754 standard. All values including intermediate results must be expressed as IEEE float or double values.
It is rarely used.
static class

method

field


initializer
Make an inner class top-level class

A class method, invoked through the class name.

A class field, invoked through the class name
one instance, regardless of class instances created.

Run when the class is loaded, rather than when an instance is created.
synchronized method For a static method, a lock for the class is acquired before executing the method. For a non-static method, a lock for the specific object instance is acquired.

transient field Not be serialized with the object, used with object serializations.
volatile field Accessible by unsynchronized threads, very rarely used.

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