java 泛型综合例子

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除了用到了泛型，还用到了<T extends Info>来设定上限。看实例：

interface Info{//只有此接口的子类才能表示人的信息}class Person<T extends Info>{           //为参数T设置一个上限，必须是Info或Info的子类。private T info;    /*构造函数*/public Person(T info){this.info=info;}public void setInfo(T info){this.info=info;}public T getInfo(){return this.info;}public String toString(T info){return this.info.toString();}}class Contact implements Info{           //表明Contact是Info的子类，他可以使用在Person中private String address;private String telphone;private String zipcode;/*构造函数*/public Contact(String address,String telphone,String zipcode){this.address=address;this.telphone=telphone;this.zipcode=zipcode;}public void setAddress(String address){this.address=address;}public String getAddress(){return this.address;}public void setTelphone(String telphone){this.telphone=telphone;}public String getTelphone(){return this.telphone;}public void setZipcode(String zipcode){this.zipcode=zipcode;}public String getZipcode(){return this.zipcode;}public String toString(){return "联系方式：" + "\n" +"\t|- 联系电话：" + this.telphone + "\n" + "\t|- 联系地址：" + this.address + "\n" + "\t|- 邮政编码：" + this.zipcode ;}}class Introduction implements Info{private String name;private String sex;private int age;/*构造函数*/public Introduction(String name,String sex,int age){this.name=name;this.sex=sex;this.age=age;}public void setName(String name){this.name=name;}public String getName(){return this.name;}public void setSex(String sex){this.sex=sex;}public String getSex(){return this.sex;}public void setAge(int age){this.age=age;}public int getAge(){return this.age;}public String toString(){return "基本信息：" + "\n" +"\t|- 姓名：" + this.name + "\n" + "\t|- 性别：" + this.sex + "\n" + "\t|- 年龄：" + this.age ;}}public class ExampleFanxing{public static void main(String[] args){Person<Contact> p=null;Person<Introduction> p1=null;Contact c = new Contact("110","北三环东路","100029");Introduction i= new Introduction("武开英","男",22);p = new Person<Contact>(c);p1=new Person<Introduction>(i);System.out.print(p.getInfo().toString());System.out.print(p1.getInfo().toString());}}

class Person<T extends Info>{}表明了Person类的上限，只能是Info或Info的子类。类Contact和Introduction继承了接口Info，满足条件。

如果去掉Contact类中的implements Info会出现如下错误：

E:\JAVA\NotePadJava\Demo1>javac ExampleFanxing.java
ExampleFanxing.java:100: 错误: 类型参数Contact不在类型变量T的范围内
Person<Contact> p=null;
^
其中, T是类型变量:
T扩展已在类 Person中声明的Info
ExampleFanxing.java:104: 错误: 类型参数Contact不在类型变量T的范围内
p = new Person<Contact>(c);
^
其中, T是类型变量:
T扩展已在类 Person中声明的Info
2 个错误

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