java.lang.ClassCastException : java. lang.String 无法转换为 [Ljava.lang.Object; - 使用 hibernate 从数据库中获取查询

Question

这个问题已经有答案了:

java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.Object (3 个回答)

已关闭 7 年前。

我正在尝试从数据库中获取不同的记录。这是我的尝试

@SuppressWarnings("unchecked")
    @Override
    public List<Employee> getAllEmployees(String employeeName) { 
    String query = "SELECT DISTINCT e.name FROM Employees e WHERE e.name like '%"+ employeeName +"%'";
        List<Object[]> employeeObjects = hibernateUtil.fetchAll(query);
        List<Employee> employees = new ArrayList<Employee>();
        for(Object[] employeeObject: employeeObjects) {
            Employee employee = new Employee();
            long id = ((BigInteger) employeeObject[0]).longValue();         
            int age = (int) employeeObject[1];
            String name = (String) employeeObject[2];
            float salary = (float) employeeObject[3];
            employee.setId(id);
            employee.setName(name);
            employee.setAge(age);
            employee.setSalary(salary);
            employees.add(employee);
        }
        System.out.println(employees);
        return employees;
    }

这是发生错误的行

for(Object[] employeeObject: employeeObjects) { //line 65

当我尝试搜索记录时出现此错误

java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.Object;
    com.ranga.dao.impl.EmployeeDAOImpl.getAllEmployees(EmployeeDAOImpl.java:65)
    com.ranga.service.impl.EmployeeServiceImpl.getAllEmployees(EmployeeServiceImpl.java:48)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:497)
    org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
    org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
    com.sun.proxy.$Proxy23.getAllEmployees(Unknown Source)
    com.ranga.controller.EmployeeController.searchEmployee(EmployeeController.java:73)

请问哪里出了问题？

Answer 1

您的查询是:

SELECT DISTINCT e.name FROM Employees e WHERE e.name like '%"+ employeeName +"%'

_{(未参数化。糟糕。非常糟糕。顽皮的开发人员!)}

因此您选择唯一的 e.name来自Employees - 这意味着你会得到一些名字。

因此我怀疑hibernateUtil.fetchAll返回 List<String> .

你会:

List<Object[]> employeeObjects = hibernateUtil.fetchAll(query);

我怀疑这是来自 List<?> 的不安全转换或List (原始)。

然后你就这样做

for(Object[] employeeObject: employeeObjects) {
...
}

此时，Java 会将项目转换到 List 中。到所需的类型，即 Object[] 。因此你的错误。