Java Reference
In-Depth Information
A final method may not be overridden or hidden by a subclass, which makes
it amenable to compiler optimizations that are not possible for regular meth‐
ods. All private methods are implicitly final , as are all methods of any class
that is declared final .
a x
nativ The native modifier specifies that the method implementation is written in
some “native” language such as C and is provided externally to the Java pro‐
gram. Like abstract methods, native methods have no body: the curly braces
are replaced with a semicolon.
Implementing native Methods
When Java was first released, native methods were sometimes used for efficiency
reasons. That is almost never necessary today. Instead, native methods are used to
interface Java code to existing libraries written in C or C++. native methods are
implicitly platform-dependent, and the procedure for linking the implementation
with the Java class that declares the method is dependent on the implementation of
the Java virtual machine. native methods are not covered in this topic.
public, protected, private
These access modifiers specify whether and where a method can be used out‐
side of the class that defines it. These very important modifiers are explained in
Chapter 3 .
A method declared static is a class method associated with the class itself
rather than with an instance of the class (we cover this in more detail in Chap‐
ter 3 ).
The fp in this awkwardly named, rarely used modifier stands for “floating
point.” Java normally takes advantage of any extended precision available to the
runtime platform's floating-point hardware. The use of this keyword forces Java
to strictly obey the standard while running the strictfp method and only per‐
form floating-point arithmetic using 32- or 64-bit floating-point formats, even
if this makes the results less accurate.
The synchronized modifier makes a method threadsafe. Before a thread can
invoke a synchronized method, it must obtain a lock on the method's class (for
static methods) or on the relevant instance of the class (for non- static
methods). This prevents two threads from executing the method at the same
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