学步园

package com.shengsiyuan.a.b.c.d.e.f.g.h.i.j.k;
            public class PackageTest

         {
               public static void main(String[] args)
                    {
                   System.out.println("hello world");
                  }
       }

//调用是 用 javac.PackageTest.java

 //然后用 javac  -d . PackageTest.java

//执行用 java com.shengsiyuan.a.b.c.d.e.f.g.h.i.j.k.PackageTest
.