s-day02-泛型通配符的使用(了解)

2026-07-31 11:45:48 +08:00
parent 6bdf2742a2
commit 7e9ae0104d
3 changed files with 74 additions and 0 deletions
@@ -0,0 +1,33 @@
+package com.inmind.generic_tpf08;
+
+import java.util.ArrayList;
+
+/*
+13.泛型通配符的使用(了解) ?
+当我们要接受一个数据类型，它的泛型不一致，要使用泛型通配符，匹配？
+ */
+public class Demo10 {
+    public static void main(String[] args) {
+        //创建人和学生的2个集合
+        ArrayList<Person> list1 = new ArrayList<>();
+        list1.add(new Person("小王1", 18));
+        list1.add(new Person("小王2", 18));
+        //遍历打印集合中的内容
+        showList(list1);
+
+        ArrayList<Student> list2 = new ArrayList<>();
+        list2.add(new Student("小王3", 18));
+        list2.add(new Student("小王4", 18));
+        //遍历打印集合中的内容
+        showList(list2);
+    }
+
+    /*
+        ArrayList<Object> 这样写的话是错的，泛型是没有多态的
+     */
+    public static void showList(ArrayList<?> list){
+        for (Object o : list) {
+            System.out.println(o);
+        }
+    }
+}
@@ -0,0 +1,22 @@
+package com.inmind.generic_tpf08;
+
+public class Person {
+    String name;
+    int age;
+
+    public Person() {
+    }
+
+    public Person(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "Person{" +
+                "name='" + name + '\'' +
+                ", age=" + age +
+                '}';
+    }
+}
@@ -0,0 +1,19 @@
+package com.inmind.generic_tpf08;
+
+public class Student extends Person{
+
+    public Student() {
+    }
+
+    public Student(String name, int age) {
+        super(name, age);
+    }
+
+    @Override
+    public String toString() {
+        return "Student{" +
+                "age=" + age +
+                ", name='" + name + '\'' +
+                '}';
+    }
+}