static与final

1.static修饰的类或成员变量随着JVM将类加载到方法区被分配内存空间.在JVM执行过程中只实例化一次.例如

public class StaticClass {
  public static int a = 5;
}

public class Test {
  public static void main(String[] args) {
    StaticClass sc = new StaticClass();
    sc.a = 10;
    StaticClass sc2 = new StaticClass();
   
    System.out.println(sc.a);
    System.out.println(sc2.a);
    System.out.println(StaticClass.a);
  }
}

main()方法输出
10
10
10

2.final类型的变量赋值后就不能再改变