Java Pocket Guide, 4th Edition

Chapter 8. Java Modifiers

Modifiers, which are Java keywords, may be applied to classes, interfaces, constructors, methods, and data members.

Table 8-1 lists the Java modifiers and their applicability. Note that private and protected classes are allowed, but only as inner or nested classes. Reference Chapter 21 for accessibility details relative to Java 9.

Table 8-1. Java modifiers

Modifier	Class	Interface	Constructor	Method	Data member
Access modifiers
package-private	Yes	Yes	Yes	Yes	Yes
private	No	No	Yes	Yes	Yes
protected	No	No	Yes	Yes	Yes
public	Yes	Yes	Yes	Yes	Yes
Other modifiers
abstract	Yes	Yes	No	Yes	No
final	Yes	No	No	Yes	Yes
native	No	No	No	Yes	No
strictfp	Yes	Yes	No	Yes	No
static	No	No	No	Yes	Yes
synchronized	No	No	No	Yes	No
transient	No	No	No	No	Yes
volatile	No	No	No	No	Yes

Inner classes may also use the private or protected access modifiers. Local variables may only use one modifier: final.

Access Modifiers

Access modifiers define the access privileges of classes, interfaces, constructors, methods, and data members. Access modifiers consist of public, private, and protected. If no modifier is present, the default access of package-private is used.

Table 8-2 provides details on visibility when access modifiers are used.

Table 8-2. Access modifiers and their visibility

Modifier	Visibility
package-private	The default package-private limits access from within the package.
private	The private method is accessible from ...