泛型类、泛型方法、泛型接口

src/chapter6/Example22.java

@@ -1,4 +1,33 @@
 package chapter6;
 
-public class Example22 {
+// T 标识一个不确定的类型
+class Score<T> {
+    private String studentName;     // 学生姓名
+    private String subject;         // 课程名称
+    private T value;                // 成绩值（可以是任意类型）
+
+    // 构造方法
+    public Score(String studentName, String subject, T value) {
+        this.studentName = studentName;
+        this.subject = subject;
+        this.value = value;
+    }
+
+    public String toString() {
+        return studentName + "的" + subject + "成绩是" + value;
+    }
+}
+
+public class Example22 {
+    public static void main(String[] args) {
+        // 创建三个成绩对象，分别存储小明的数学、英语、军事理论成绩
+        Score<Integer> s1 = new Score<Integer>("小明", "数学", 100);
+        Score<String> s2 = new Score<String>("小明", "英语", "A");
+        Score<String> s3 = new Score<String>("小明", "军事理论", "合格");
+
+        // 打印三门课程的成绩
+        System.out.println(s1);
+        System.out.println(s2);
+        System.out.println(s3);
+    }
 }

src/chapter6/Example23.java

@@ -1,4 +1,29 @@
 package chapter6;
 
+
+import java.util.ArrayList;
+import java.util.Iterator;
+
+
 public class Example23 {
+    public static void main(String[] args) {
+        // 存放字符串的集合
+        ArrayList<String> names = new ArrayList<String>();
+        names.add("张三");  // √ 正确
+
+        Iterator it1 = names.iterator();
+        while (it1.hasNext()) {
+            String name = (String) it1.next();
+            System.out.println(name);
+        }
+
+        ArrayList students = new ArrayList();
+        names.add("张三");
+
+        Iterator it2 = students.iterator();
+        while (it2.hasNext()) {
+            String student = (String) it2.next();
+            System.out.println(student);
+        }
+    }
 }

src/chapter6/Example24.java

@@ -1,4 +1,36 @@
 package chapter6;
 
+
+
 public class Example24 {
+    // 泛型方法：验证订单信息
+    public static  <T> boolean verify(T info) {
+        System.out.println("正在验证: " + info);
+
+        if (info instanceof String) {
+            // 验证订单号
+            String orderNo = (String) info;
+            return orderNo.length() == 10;  // 假设订单号必须是10位
+        }
+        else if (info instanceof Double || info instanceof Integer) {
+            // 验证订单金额
+            double amount = Double.parseDouble(info.toString());
+            return amount > 0;  // 金额必须大于0
+        }
+        return false;
+    }
+
+    public static void main(String[] args) {
+        // 验证订单号
+        boolean isValidOrderNo = verify("A123456789");
+        System.out.println("订单号是否合法: " + isValidOrderNo);
+
+        // 验证订单金额
+        boolean isValidAmount = verify(99.9);
+        System.out.println("订单金额是否合法: " + isValidAmount);
+
+        // 验证负数金额
+        boolean isValidNegative = verify(-10.0);
+        System.out.println("负数金额是否合法: " + isValidNegative);
+    }
 }

src/chapter6/Example25.java

@@ -1,4 +1,59 @@
 package chapter6;
 
-public class Example25 {
+// 定义支付接口（泛型接口）
+interface Payment<T> {
+    boolean pay(T amount);    // 支付方法
+    T getBalance();           // 获取余额
+}
+
+// 方式一：明确类型的接口实现 - 支付宝支付
+class AliPay implements Payment<Double> {
+    private Double balance = 1000.0;
+
+    @Override
+    public boolean pay(Double amount) {
+        if (balance >= amount) {
+            balance -= amount;
+            System.out.println("支付成功：" + amount + "元");
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public Double getBalance() {
+        return balance;
+    }
+}
+
+// 方式二：泛型类型的接口实现 - 校园卡支付
+class CampusCard<T> implements Payment<T> {
+    private T balance;
+
+    public CampusCard(T balance) {
+        this.balance = balance;
+    }
+
+    @Override
+    public boolean pay(T amount) {
+        System.out.println("支付积分：" + amount);
+        return true;
+    }
+
+    @Override
+    public T getBalance() {
+        return balance;
+    }
+}
+
+public class Example25 {
+    public static void main(String[] args) {
+        // 测试支付宝支付
+        AliPay aliPay = new AliPay();
+        aliPay.pay(100.0);
+
+        // 测试校园卡支付
+        CampusCard<Integer> campusCard = new CampusCard<>(500);
+        campusCard.pay(100);
+    }
 }