Question

我有json字符串，我想从该字符串中获取数据..

jsonString 数据就像

[{"Eid":"1","name":"Rahim"},{"Eid":"2","name":"Karim"}]

我试过下面的代码

员工类

public class Employee {
    private String Eid;
    private String name;
//setters and getters

Employee(){};//constructor
Employee(String Eid,String name){}//constructor


}

主要课程

try{

JSONArray jsonarray = new JSONArray(jsonString);

Gson gson = new Gson();

Employee employee = new Employee();

employee=  gson.fromJson(jsonarray.toString(), Employee.class);

//display every employee details
logger.info(employee);

 }
 catch (Exception e) {

logger.error("Employee save > Error: " + e.getMessage());

}

但是得到错误：

Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2

Answer 1

请尝试以下代码：

Employee[] employeeArray=  gson.fromJson(jsonarray.toString(), Employee[].class);

// iterate on employeeArray
for(Employee employee :employeeArray){
   // here you can do your task on employee object 
 }

Answer 2

您正在阅读员工记录集而不是单个员工集。所以你应该使用ArrayList或任何List类

修改下面的代码（我已经测试过相同的工作正常）

try{ 
  //we dont need json array .. just use the json string
  Gson gson = new Gson();
  Employee employee = new Employee();
  List<Employee> employeeList = gson.fromJson(jsonString, ArrayList.class);    
  //display every employee list details
  logger.info("employeeList : " + employeeList.size()); 
 }

[output] employeeList : 2

演示： Test.java

public class Test {
    public static void main(String[] args) {
        try {
            String json = "[{\"Eid\":\"1\",\"name\":\"Rahim\"},{\"Eid\":\"2\",\"name\":\"Karim\"}]";
            System.out.println(json);
            Gson gson = new Gson();
            List<Employee> employeeList =  gson.fromJson(json, ArrayList.class);
            System.out.println(employeeList.size());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Employee.java

public class Employee implements java.io.Serializable {
    private String Eid;
    private String name;

    public String getEid() {
        return Eid;
    }

    public void setEid(String eid) {
        Eid = eid;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

gson.fromJson(json, ArrayList.class);此行将从JSON准备一份员工对象列表，并在将列表分配给Employee类型[List<Employee> employeeList=gson.fromJson(json, ArrayList.class);]时，它会将对象类型转换为员工类类型。

从json数组中获取列表

2 个答案: