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2010-05-31T17:44:27Z

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== Define the static member ==

<OL><LI>You can use the keyword static in front of a field or method declaration.</LI><LI>The static keyword may come before or after the access modifier.</LI></OL>
These two are correct:



<source lang="java">
public static int a;
static public int b;</source>



<OL><LI>From inside a static method, you cannot call instance methods or instance fields because they only exist after you create an object.</LI><LI>You can access other static methods or fields from a static method.</LI><LI>You can only declare a static variable in a class level.</LI><LI>You cannot declare local static variables even if the method is static.</LI></OL>

== Demonstrates Static nested Classes ==



<source lang="java">
/*
* file: StaticNestedClassDemo.java
* package: oreilly.hcj.nested
*
* This software is granted under the terms of the Common Public License,
* CPL, which may be found at the following URL:
* http://www-124.ibm.ru/developerworks/oss/CPLv1.0.htm
*
* Copyright(c) 2003-2005 by the authors indicated in the @author tags.
* All Rights are Reserved by the various authors.
*
########## DO NOT EDIT ABOVE THIS LINE ########## */
/**
* Demonstrates Static nested Classes.
*
* @author
* @version $Revision: 1.5 $
*/
private static class SomeOtherClass {
/**
* a demo method.
*/
public void someMethod() {
System.out.println("Protect me!");
}
}
}
/* ########## End of File ########## */</source>



== Demonstrate static variables, methods, and blocks. ==



<source lang="java">
class UseStatic {
static int a = 3;
static int b;

static void meth(int x) {
System.out.println("x = " + x);
System.out.println("a = " + a);
System.out.println("b = " + b);
}

static {
System.out.println("Static block initialized.");
b = a * 4;
}

public static void main(String args[]) {
meth(42);
}
}</source>



== Initializer for final static field ==



<source lang="java">
public class ClassInitializer7
{
final static int classField;
static
{
classField = 29;
}
public static void main (String [] args)
{
System.out.println (classField);
}
}</source>



== Inside main( ), the static method callme( ) and the static variable b are accessed outside of their class. ==



<source lang="java">
class StaticDemo {
static int a = 42;
static int b = 99;
static void callme() {
System.out.println("a = " + a);
}
}

class StaticByName {
public static void main(String args[]) {
StaticDemo.callme();
System.out.println("b = " + StaticDemo.b);
}
}</source>



== Reference inner static class ==



<source lang="java">
class MyClassesDemo {
public static void main(String[] args) {
MyClass tlc = new MyClass();
MyClass.NestedMyClass ntlc;
ntlc = new MyClass.NestedMyClass();
}
}
class MyClass {
private int i;
private static String name = "MyClass";
{
System.out.println("Assigning 1 to i");
i = 1;
}
static class NestedMyClass {
int j;
{
System.out.println("Assigning 2 to j");
j = 2;
System.out.println(name);
}
}
}</source>



== reference static field after declaration ==



<source lang="java">
public class ClassInitializer3 {
static int classField1 = 1;
static int classField2 = 1 + classField1;
public static void main(String[] args) {
System.out.println(classField1);
System.out.println(classField2);
}
}</source>



== Static field, constructor and exception ==



<source lang="java">
public class Main {
static Bar bar;
static {
try {
bar = new Bar();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] argv) {
System.out.println(bar);
}
}
class Bar {
public Bar() throws Exception {
}
public String toString() {
return "Bar";
}
}</source>



== Static Members ==

<OL><LI>Static members are not tied to class instances.</LI><LI>Static members can be called without having an instance.</LI></OL>
The out field in java.lang.System is static.



<source lang="java">
public class MainClass {
public static void main() {
System.out.println("123");
}
}</source>



the method main(the entry point to a class) is static because it must be called before any object is created.

== static section Initializer and logic ==



<source lang="java">
public class ClassInitializer6 {
static int classField = 3;
static {
System.out.println(" : " + classField);
classField = 1;
for (int i = 2; i < 6; i++)
classField *= i;
}
static {
System.out.println(" = " + classField);
}
public static void main(String[] args) {
System.out.println(classField);
}
}</source>



== static section of Initializer ==



<source lang="java">
public class ClassInitializer5 {
static String tz;
static {
java.util.Properties p = System.getProperties();
p.list(System.out);
tz = p.getProperty("user.timezone");
if (tz.equals(""))
tz = "Default";
}
public static void main(String[] args) {
System.out.println("timezone = " + tz);
}
}</source>

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