No primary or default constructor found for interface java.util.List]

spring报错：

2021-12-01 09:51:41.548 ERROR 3884 --- [nio-8080-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: No primary or default constructor found for interface java.util.List] with root cause

java.lang.NoSuchMethodException: java.util.List.()
	at java.lang.Class.getConstructor0(Class.java:3082) ~[na:1.8.0_162]
	at java.lang.Class.getDeclaredConstructor(Class.java:2178) ~[na:1.8.0_162]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.35.jar:9.0.35]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.35.jar:9.0.35]

先直接说原因：

    @PostMapping("/test/param/list")
    public void testParamList(@RequestParam(value = "param") List param) {
        System.out.println(param);
    }

方法上少了注解@RequestParam(value = "param")

但是如果参数使用数组形式，就不用加这个注解了，如：

    @PostMapping("/test/param/list")
    public void testParamList(String[] param) {
        System.out.println(param);
    }

测试代码示例：
HTML：

    
    




  

    param1: 

    param2: 

    param3: 

    提交
  

java代码：

@RestController
@RequestMapping("/DemoController")
public class DemoController {
    @PostMapping("/test/param/list")
    public void testParamList(@RequestParam(value = "param") List param) {
        System.out.println(param);
    }
}

如果不加注解@RequestParam(value = "param")，就会报No primary or default constructor found for interface java.util.List]