The extended for statement causes ClassCastException.

Asked 2 months ago, Updated 2 months ago, 3 views

ClassCastException occurs in the extended for statement.How do I fix the Id of each Student object to the console so that there are no errors?Thank you.

 ■ Test class
@ Controller    
public class test {

    @RequestMapping(value="/login", method=RequestMethod.GET)
    public String login(@RequestParam(value="name", required=false, defaultValue="World") String name, Model model) {


        RestTemplate restTemplate = new RestTemplate();
        @SuppressWarnings ("unchecked")
        List<Student>aiu=restTemplate.getForObject("http://localhost:9292/student?userId=00002", List.class);

        for (Student a:aiu) {
            System.out.println(a.getId());

        }
        return "login";
    }
}

■ Student Class
public class Student {
    private String id;
    private String name;
    private String score;
    public String getId() {
        return id;
    }
    public void setId(String id){
        this.id=id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name){
        this.name = name;
    }
    public String getScore() {
        return score;
    }
    public void setScore(String score){
        This.score=score;
    }
}

■ StudentController Class
@RestController
public class StudentController {

    @RequestMapping(value="/student", method=RequestMethod.GET)

    publicList<Student>get(@RequestParamStringuserId){

        List<Student>a=new ArrayList<Student>();

        Student aa = new Student();
        aa.setId("0001");
        aa.setName("Ando");
        aa.setScore("30");

        Student ab = new Student();
        ab.setId("0002");
        ab.setName("Tanaka");
        ab.setScore("48");

        a.add(aa);
        a.add(ab);

        return a;
    }
}

spring-boot java8

2022-09-30 14:30

1 Answers

The code below does not specify a list type, so
I think the element will be Object and ClassCastException will occur.

List<Student>aiu=restTemplate.getForObject("...", List.class);

If you receive it in a Student array as follows,
ClassCastException will no longer occur.

ResponseEntity<Student[]>responseEntity= 
    restTemplate.getForEntity(url, Student[].class);
Student [] aiu=responseEntity.getBody();


2022-09-30 14:30

If you have any answers or tips


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