android 无法为Product.class调用无参数构造函数

6ovsh4lw 于 2023-04-10 发布在 Android

关注(0)|答案(3)|浏览(80)

我正在使用GSON和Volley库在我的Android应用程序中联网，但在使用Gson将Json响应转换为Model类时，我得到了以下错误：

88-2006/ E/Volley﹕ [121] NetworkDispatcher.run: Unhandled exception java.lang.RuntimeException: Unable to invoke no-args constructor for class [Lcom.example.model.Product;. Register an InstanceCreator with Gson for this type may fix this problem.
    java.lang.RuntimeException: Unable to invoke no-args constructor for class [Lcom.example.model.Product;. Register an InstanceCreator with Gson for this type may fix this problem.

以下是我正在使用的POJO类：Product.java

public class Product {

    private String status;

    private List<Result> results = new ArrayList<Result>();

    private Pagination pagination;
    public Product(){}

    // getters and setters
}

Pagination.java

public class Pagination {

    private String first;

    private String previous;

    private String next;

    private String last;
    public Pagination(){}
}

Result.java

public class Result {

    private String id;

    private Properties properties;
    public Result{}

}
Properties.java

public class Properties {

    private String qbcode;

    private String name;

    private String purchasedate;

    private String vendor;

    private String thumbnail;
    public Properties(){}
}

我已经通过了现有的问题，这是一样的，作为每一个答案，我发现我添加了无参数构造函数的所有类，但我仍然得到的错误，请帮助我解决这个问题
JSON字符串：

{
  "status" : "OK",
  "results" : [ {
    "id" : "IzIzOjE=",
    "properties" : {
      "qbcode" : "IN-1-1",
      "name" : "Test Name",
      "purchasedate" : "2015-05-21",
      "vendor" : "Test Vendor",
      "thumbnail" : "http://en.wikipedia.org/static/images/project-logos/enwiki.png"
    }
  }, {
    "id" : "IzIzOjI=",
    "properties" : {
      "qbcode" : "IN-1-2",
      "name" : "Test Name",
      "purchasedate" : "2015-05-21",
      "vendor" : "Test Vendor",
      "thumbnail" : "http://en.wikipedia.org/static/images/project-logos/enwiki.png"
    }
  }, {
    "id" : "IzIzOjM=",
    "properties" : {
      "qbcode" : "IN-1-3",
      "name" : "Test Name",
      "purchasedate" : "2015-05-21",
      "vendor" : "Test Vendor",
      "thumbnail" : "http://en.wikipedia.org/static/images/project-logos/enwiki.png"
    }
  },{
    "id" : "IzIzOjU=",
    "properties" : {
      "qbcode" : "IN-1-5",
      "name" : "Test Name",
      "purchasedate" : "2015-05-21",
      "vendor" : "Test Vendor",
      "thumbnail" : "http://en.wikipedia.org/static/images/project-logos/enwiki.png"
    }
  } ],
  "pagination" : {
    "first" : "/list?size=20",
    "previous" : "/list?start=IzIzOjE=&size=20",
    "next" : "/list?start=IzIzOjQx&size=20",
    "last" : "/list?start=IzIzOjYx&size=20"
  }
}

android

来源：https://stackoverflow.com/questions/30371096/unable-to-invoke-no-args-constructor-for-product-class

3条答案

按热度按时间

3z6pesqy1#

为所有类添加默认构造函数。示例：

public class Product{

    public Product(){
    }

}

赞(0）回复(0）举报 2023-04-10

uurity8g2#

问题解决了，我做了一个愚蠢的调用Gson，因为我获得了一个包含其他类列表的Product类（Result.class等），但我发送Product[].class到Gson转换，因此它抛出异常。

赞(0）回复(0）举报 2023-04-10

ilmyapht3#

您的模型具有私有属性，您必须为相同的属性创建setter或创建具有所有参数的构造函数，如下所示：

public class Product {

    private String status;
    private List<Result> results = new ArrayList<Result>();
    private Pagination pagination;

    public void setStatus(String status) {
        this.status = status;
    }

    public void setResults(List<Result> results) {
        this.results = results;
    }

    public void setPagination(Pagination pagination) {
        this.pagination = pagination;
    }
}

或

public class Product {

    private String status;
    private List<Result> results = new ArrayList<Result>();
    private Pagination pagination;

    public Product(String status, List<Result> results, Pagination pagination) {
        this.status = status;
        this.results = results;
        this.pagination = pagination;
    }

}

赞(0）回复(0）举报 2023-04-10

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android 无法为Product.class调用无参数构造函数

3条答案

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