代码如下：

import javax.swing.JOptionPane;
 
public class Java_1 {
    //*********Found********** 
    public static  void main(String args[]) {
        PackageData d = new PackageData();
        String output;
        output = "实例化后:\n" + d.toString();
        d.x = 77; //修改包访问的数据 
        //*********Found********** 
        d.s = "祝您成功!"; //修改包访问的数据 
        output += "\n修改数据后的访问结果:\n" + d.toString();
        //*********Found********** 
        JOptionPane.showMessageDialog(null, output,
                "对包的访问示范",
                JOptionPane.INFORMATION_MESSAGE);
        System.exit(0);
    }
}
 
class PackageData {
    int x; //访问包的实例变量 
    String s; //访问包的实例变量 
    //构造方法 
    public PackageData() {
        x = 0;
        s = "Hello";
    }
 
    public String toString() {
        return "x: " + x + " s: " + s;
    }
}