摘要：最近，公司要求将JDK升级到Java 17，我一开始是拒绝的——“不就是个LTS版本吗？能有什么新花样？”结果，当我用上新特性后，直接删掉了50%的冗余代码！原来Java也能这么优雅！
最近，公司要求将JDK升级到Java 17，我一开始是拒绝的——“不就是个LTS版本吗？能有什么新花样？” 结果，当我用上新特性后，直接删掉了50%的冗余代码！原来Java也能这么优雅！
今天，我就带大家解锁Java 17的五大杀手级语法糖，让你写代码像写诗一样简洁！
String json = "{\n" + " \"name\": \"张三\",\n" + " \"age\": 25,\n" + " \"address\": \"北京市朝阳区\"\n" + "}";效果对比：
if (obj instanceof String) { String str = (String) obj; System.out.println(str.toUpperCase); } else if (obj instanceof Integer) { Integer num = (Integer) obj; System.out.println(num * 2); } if (obj instanceof String str) { System.out.println(str.toUpperCase); } else if (obj instanceof Integer num) { System.out.println(num * 2); } String dayType; switch (day) { case"Monday": case"Tuesday": case"Wednesday": case"Thursday": case"Friday": dayType = "工作日"; break; case"Saturday": case"Sunday": dayType = "周末"; break; default: dayType = "未知"; } String dayType = switch (day) { case "Monday", "Tuesday", "Wednesday", "Thursday", "Friday" -> "工作日"; case "Saturday", "Sunday" -> "周末"; default -> "未知"; };效果对比：
public class Animal { ... } public class Dog extends Animal { ... } public class Cat extends Animal { ... } // 非法继承 public class Unicorn extends Animal { ... } public sealed class Animal permits Dog, Cat { ... } public final class Dog extends Animal { ... } public final class Cat extends Animal { ... } // 编译错误：Unicorn不是Animal的合法子类 public class Unicorn extends Animal { ... } public class User { private final String name; private final int age; public User(String name, int age) { this.name = name; this.age = age; } public String getName { return name; } public int getAge { return age; } @Override public boolean equals(Object o) { ... } @Override public int hashCode { ... } @Override public String toString { ... } } public class OrderService { public String processOrder(Object order) { if (order instanceof OnlineOrder) { OnlineOrder onlineOrder= (OnlineOrder) order; return"处理在线订单：" + onlineOrder.getOrderId; } elseif (order instanceof OfflineOrder) { OfflineOrder offlineOrder= (OfflineOrder) order; return"处理线下订单：" + offlineOrder.getOrderId; } else { thrownew IllegalArgumentException("未知订单类型"); } } } public class OrderService { public String processOrder(Object order) { return switch (order) { case OnlineOrder onlineOrder -> "处理在线订单：" + onlineOrder.orderId; case OfflineOrder offlineOrder -> "处理线下订单：" + offlineOrder.orderId; default -> thrownew IllegalArgumentException("未知订单类型"); }; } } // 使用Records定义订单类型 public record OnlineOrder(String orderId) { } public record OfflineOrder(String orderId) { }效果对比：
• 代码量减少 60%• 逻辑更清晰来源：散文随风想
