59 lines
1.8 KiB
Java
59 lines
1.8 KiB
Java
package com.inmind.generic_advance06;
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import java.util.ArrayList;
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/*
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13.泛型通配符的使用(了解)
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当我们想接收一个数据类型，它们的泛型不一致，但是方法中的操作是一致的时候，如果操作？？？？
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泛型通配符:?,它的作用是能够匹配任意的泛型类型
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*/
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public class Demo07 {
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public static void main(String[] args) {
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//创建3个人
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Person p1 = new Person("张三", 18);
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Person p2 = new Person("李四", 19);
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Person p3 = new Person("王五", 20);
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ArrayList<Person> pLists = new ArrayList<>();
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pLists.add(p1);
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pLists.add(p2);
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pLists.add(p3);
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//把集合中的对象，使用foreach遍历打印打印输出,本质是迭代器
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/*for (Person p : pLists) {
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System.out.println(p);//将p的toString的方法返回值，打印出来
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}*/
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// showPerson(pLists);
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show(pLists);
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//创建3个学生
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ArrayList<Student> sLists = new ArrayList<>();
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sLists.add(new Student("刘备", 17));
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sLists.add(new Student("关羽", 16));
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sLists.add(new Student("张飞", 15));
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/*for (Student s : sLists) {
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System.out.println(s);
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}*/
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show(sLists);
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}
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//注意：ArrayList<Object>参数类型时，泛型是没有多态！！！！
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public static void show(ArrayList<?> list){
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for (Object o : list) {
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System.out.println(o);
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}
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}
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/* public static void showPerson(ArrayList<Person> list){
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for (Person person : list) {
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System.out.println(person);
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}
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}
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public static void showStudent(ArrayList<Student> list){
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for (Student s : list) {
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System.out.println(s);
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}
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}*/
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}
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