Java中静态变量的适用场景

Java类中的静态变量在程序运行期间，其内存空间对所有该类的对象实例而言是共享的，有些时候可以认为是全局变量。因此在某些时候为了节省系统内存开销、共享资源，可以将类中的一些变量声明为静态变量，通过下面的例子，你可以发现合理应用静态变量带来的好处：

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Java代码

public class WeekA{
static class Data {
private int week;
private String name;
Data(int i, String s) {
week= i;
name = s;
}
}
Data weeks[] = {
new Data(1, "Monday"), new Data(2, "Tuesay"), new Data(3, "Wednesday"), new Data(4, "Thursday"), new Data(5, "Friday"), new Data(6, "Saturday"), new Data(7, "Sunday")
};
public static void main(String args[]) {
final int N = 10000;
WeekA weekinstance;
for (int i = 1; i <= N; i++){
weekinstance = new WeekA ();
}
}
}
public class WeekA{
static class Data {
private int week;
private String name;
Data(int i, String s) {
week= i;
name = s;
}
}
Data weeks[] = {
new Data(1, "Monday"), new Data(2, "Tuesay"), new Data(3, "Wednesday"), new Data(4, "Thursday"), new Data(5, "Friday"), new Data(6, "Saturday"), new Data(7, "Sunday")
};
public static void main(String args[]) {
final int N = 10000;
WeekA weekinstance;
for (int i = 1; i <= N; i++){
weekinstance = new WeekA ();
}
}
}

在上面这段代码中，没有将Data weeks声明为静态变量，因此当创建WeekA对象时将会得到10 000个weeks对象的副本，这些对象被保存在内存中，但是weeks对象中的数据却从来没有被更改过，而且十分稳定。因此，如果能使所有对象共享该数据对象是个不错的解决办法，请看下面的代码：
Java代码

public class WeekB{
static class Data {
private int week;
private String name;
Data(int i, String s) {
week= i;
name = s;
}
}
static Data weeks[] = {
new Data(1, "Monday"), new Data(2, "Tuesay"), new Data(3, "Wednesday"), new Data(4, "Thursday"), new Data(5, "Friday"), new Data(6, "Saturday"), new Data(7, "Sunday")
};
public static void main(String args[]) {
final int N = 10000;
WeekB weekinstance;
for (int i = 1; i <= N; i++){
weekinstance = new WeekB ();
}
}
}
public class WeekB{
static class Data {
private int week;
private String name;
Data(int i, String s) {
week= i;
name = s;
}
}
static Data weeks[] = {
new Data(1, "Monday"), new Data(2, "Tuesay"), new Data(3, "Wednesday"), new Data(4, "Thursday"), new Data(5, "Friday"), new Data(6, "Saturday"), new Data(7, "Sunday")
};
public static void main(String args[]) {
final int N = 10000;
WeekB weekinstance;
for (int i = 1; i <= N; i++){
weekinstance = new WeekB ();
}
}
}