JDK17新特性
YuWei Wu 11/15/2023 Java
# Switch新写法
var score = "e";
int b = 10;
switch (score) {
case "a" -> b += 1;
case "b" -> b += 2;
default -> b += 10;
}
System.out.println(b);
# 代码块
String xmlText = """
<html>
<head>Title</head>
<body>
<p>Body</p>
</body>
</html>
""";
System.out.println(xmlText);
# 不可变类
public record Cat(String name,String address) {
public void printfAll(){
System.out.println(name+address);
}
}
Cat cat = new Cat("tom", "L.A");
Cat cat1 = new Cat("tom", "L.A");
System.out.println(cat.address());
cat.printfAll();
System.out.println(cat.equals(cat1));
# 密封类
接口Run只允许Man类实现。类同理。
public sealed interface Run permits Man{
}
public final class Man implements Run{
}
# instanceof 模式匹配
以前的写法，需要强制类型转换
if(animal instanceof Cat) {
Cat cat = (Cat) animal;
cat.eat();
} else if (animal instanceof Dog) {
Dog dog = (Dog) animal;
dog.eat();
现在可以直接简写
if(animal instanceof Cat) {
cat.eat();
} else if (animal instanceof Dog) {
dog.eat();
}
