Java Modifiers

Java Modifiers Matrix Table

There are few sets of modifers in Java Langauge:  Class Modifiers, Field Modifiers, Method Modifiers, Constructor Modifiers,   Interface Modifiers, and Member Class (inner class) Modifiers. The following table shows which modifier to which element can be applied.

element	Field	Method	Constructor	Class		Interface
modifier				top level (outer)	nested (inner)	top level (outer)	nested (inner)
abstract	no	yes	no	yes	yes	yes	yes
final	yes	yes	no	yes	yes	no	no
native	no	yes	no	no	no	no	no
private	yes	yes	yes	no	yes	no	yes
protected	yes	yes	yes	no	yes	no	yes
public	yes	yes	yes	yes	yes	yes	yes
static	yes	yes	no	no	yes	no	yes
synchronized	no	yes	no	no	no	no	no
transient	yes	no	no	no	no	no	no
volatile	yes	no	no	no	no	no	no
strictfp	no	yes	no	yes	yes	yes	yes

Rules

• The same modifier can not appear more than once in any declarations.

Rules for Class Modifiers

• The access modifier public pertains only to top level classes and to member classes;
• The access modifiers protected and private pertain only to member classes within a directly enclosing class declaration;
• The access modifier static pertains only to member classes;
• A class that contains abstract method(s) must be declared abstract;
• The class cannot be declared abstract and final simultaneously;
• The class can be declared final if its definition is complete and no subclasses are desired or required;
• The effect of the strictfp modifier is to make all float or double expressions within the class declaration be explicitly FP-strict;

Rules for Constructor Modifiers

• A constructor cannot be abstract, static, final, native, strictfp, or synchronized;
• The constructor declaration can contain only one of the access modifiers  public, protected, and private;
• If no access modifier is specified for the constructor of an enum type, the constructor is private;

Rules for Method Modifiers

• The method declaration can contain only one of the access modifiers public, protected and private;
• The abstract methods cannot be declared private, static, final, native, strictfp or synchronized;
• The methods cannot be declared native and strictfp simultaneously;
• The abstract and native methods have no body;

Rules for Field Modifiers 

• final fields cannot be volatile;

Rules for Interface Modifiers

• The access modifier public pertains only to top level interfaces and to member interfaces;
• The access modifiers protected and private pertain only to member interfaces within a directly enclosing class declaration;
• The access modifier static pertains only to member interfaces;
• Every interface is implicitly abstract; The top level interface is public and abstract;
• The effect of the strictfp modifier is to make all float or double expressions within the interface declaration be explicitly FP-strict;