没有为类型[simple type，class com ...截止日期]找到合适的构造函数：无法从JSON对象实例化

Question

我一直在努力让我的测试数据加载器在我的测试json文件中使用一个元素。我试过添加默认构造函数和各种不同的方法，但已达到我需要帮助的程度。

  

异常：失败：没有为类型[simple]找到合适的构造函数   type，class com ...截止日期]：无法从JSON对象实例化   （缺少默认构造函数或创建者，或者可能需要添加/启用   类型信息？）\ n在[来源：   sun.net.www.protocol.jar.JarURLConnection$JarURLInputStream@1d7041fb;   line：14，column：4]（通过参考链：   的java.util.ArrayList [0] - ＆GT; COM ... .core.domain.representation.AdmissionsRepresentation [\ “期限\”] - ＆GT; java.util.ArrayList中[0]）“}

json看起来像这样：

[
      {
       "id" : "d5b6754a-f8aa-49e5-8e8c-d3f7ad0df2e3",
        "rec" : 5153,
        "acc" : 1389,
        "app" : 12,
        "rate" : 66,
        "sat" : 2100,
        "act" : 31,
        "gpa" : 4.0,
        "deadlines" : [
            {
                "type" : "Priority",
                "day" : "1",
                "month" : "3"   
            },
            {
                "type" : "General",
                "day" : "15",
                "month" : "7"   
            }
        ]
      },
      {
       "id" : "d5b6754a-f8aa-49e5-8e8c-d3f7ad0df2e3",
        "rec" : 5153,
        "acc" : 1389,
        "app" : 12,
        "rate" : 66,
        "sat" : 2100,
        "act" : 31,
        "gpa" : 4.0,
        "deadlines" : [
            {
                "type" : "Priority",
                "day" : "1",
                "month" : "3"   
            },
            {
                "type" : "General",
                "day" : "15",
                "month" : "7"   
            }
        ]
      }
    ]

错误中引用的两个类的片段

public class AdmissionsRepresentation {
    private String id;
    private String created;
    private String lastModified;
    private List<Deadline> deadlines = new ArrayList<>();

  public AdmissionsRepresentation() {
    
  }

    public AdmissionsRepresentation(Admissions admissions) {
        this();
        fromDomain(admissions);
    }

    ....

    public void fromDomain(Admissions admissions) {
        setId(admissions.collegeId());

        List<Deadline> dl = admissions.deadlines();
        for (int i = 0; i < dl.size(); i++) {
            deadlines.add(dl.get(i));
        }
    }

    public Admissions toDomain() {
        ArrayList<Deadline> domainDeadlines = new ArrayList<Deadline>();
        for (int i = 0; i < deadlines.size(); i++) {
            domainDeadlines.add(deadlines.get(i));
        }

        Admissions admissions = null;
        admissions = new AdmissionsBuilder().setId(this.id)...
		.setDeadlines(domainDeadlines).build();
        return admissions;
    }


    public class Deadline implements Serializable {
        private static final long serialVersionUID = 1L;
        // private Type type;
        private String type;
        private String label;
        private String day;
        private String month;

        /*
         * public enum Type {
       
         * }
         */
        //NOTE: I have tried removing this constructor and it seems to make no difference.
        public Deadline() {

        }

        public Deadline(String type, String day, String month) {
            this.type = type;
            this.day = day;
            this.month = month;
        }

        public String getType() {
            return type;
        }

        public void setType(String type) {
            System.out.println("setting type");
            System.out.println("type: " + type.toString());
            this.type = type;
            // this.type = Type.valueOf(type);
        }
    }