从数据库中获取数据时，我在控制台中得到奇怪的输出

Question

我正在尝试获取一些数据，我正在使用 H2 数据库。型号是

@Entity
public class Employee {
    
    @Id
    private long empid;
    private String empname;
    private Date empdoj;
    private double emptotalsalary;
    private String emptype;

服务class是我使用方法的地方

@Autowired
EmployeeRepository repo;
public int countAllEmployees() {
        return (int)repo.count();
    }
    
    public List<Employee> getPermanentEmployees(String employeetype){
        Employee filter = new Employee();
        filter.setEmptype(employeetype);
        Example<Employee> example = Example.of(filter);
        List<Employee> emplist = (List<Employee>)repo.findAll();
        return emplist;
    }
    
    
    public List<Employee> getEmployeeNames(){
        Employee filter  = new Employee();
        filter.setEmpname("tha");
        ExampleMatcher matcher = ExampleMatcher.matching().withStringMatcher(StringMatcher.CONTAINING).withIgnoreCase();
        Example<Employee> example = Example.of(filter,matcher);
        return (List<Employee>)repo.findAll();
    }

在控制台中我得到这个输出

Employee Count
5
Get List of permanent Employees
[com.example.demo.Employee@416c1b0, com.example.demo.Employee@a302f30, com.example.demo.Employee@4af44f2a, com.example.demo.Employee@47994b51, com.example.demo.Employee@143fe09c]
Get List of all Employees Ending with Tha
com.example.demo.Employee@416c1b0
com.example.demo.Employee@a302f30
com.example.demo.Employee@4af44f2a
com.example.demo.Employee@47994b51
com.example.demo.Employee@143fe09c

我不明白为什么这是 coming.please 帮助。

Answer 1

我想你的意思是像 com.example.demo.Employee@143fe09c

这样的文字很奇怪

在您的代码中的某处，您正在打印员工记录。例如：System.out.println(employee) System.out.println 使用对象的 toString() 方法来打印对象。由于您没有在 Employee class 中提供它，因此它使用 Employee 的 superclass 中的 toString 方法，即 Object.

如文档中所述，它打印 classname 后跟 @ 和哈希。 https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#toString--

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
 getClass().getName() + '@' + Integer.toHexString(hashCode())

只需覆盖 Employee class 中的 toString 方法即可生成 Employee 对象的文本表示。您的 IDE 已经提供了生成此方法的好方法。

    @Override
    public String toString() {
        return "Employee{" + "empid=" + empid +
                ", empname=" + empname + "'" +
                '}';
    }

从数据库中获取数据时，我在控制台中得到奇怪的输出

I am getting Weird output in console when fetching Data from Database

h2

spring-data-jpa