十二 java面向对象程序设计(类的继承)
/**
* 类的继承
*/
class Person
{
private String name;
private int age;
public String setName(String name){this.name = name;return name;}
public int setAge(int age){this.age = age;return age;}
public void getInfo()
{
System.out.println("name = " + name + ", age = " + age);
}
}
/*
class Student //Student类重复定义了Person类的方法和成员变量
{
private String name;
private int age;
public String setName(String name){this.name = name;return name;}
public int setAge(int age){this.age = age;return age;}
public void getInfo()
{
System.out.println("name = " + name + ", age = " + age);
}
private String school;
public String setSchool(String school){this.school = school; return school;}
public void study()
{
System.out.println("study in " + school);
}
}
*/
/**
* 1,通过继承可以简化类的定义 。
*/
class Student extends Person //通过继承,这些重复的定义将被省略.
{
private String school;
public String setSchool(String school){this.school = school; return school;}
public void study()
{
System.out.println("study in " + school);
}
public static void main(String[] args)
{
Person p1 = new Person();
p1.setName("unknown");p1.setAge(0);
//p1.setSchool("unknown");错误,父类不能访问子类的成员.
p1.getInfo();
//p1.study();错误,父类不能访问子类的成员.
Person p2 = new Student();
p2.setName("mike");
p2.setAge(23);
((Student)p2).setSchool("Cambridge");
p2.getInfo();
((Student)p2).study();
//父类的对象可以向下转型.
Student s1 = new Student();
s1.setName("jackson");
因为项目有个需求，要求能够在某个预定时间对特定报表进行自动打印。报表的形式主要是excel。如果是c++或者c#什么的，简直是小菜一碟。可惜，偏偏是java实现。并且，这又不同于常见的页面手工打印，可以通过javascript调用打印机来实现。于是乎，开始摸索如何实现该功能。
首� ......
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
public class test {
public static void main(String[] args) {
ArrayList<ArrayList<Integer>> list = getArrays(1, 20, 30);
Iterator<ArrayList<Integer>> iter = list.itera ......
