Question

我正在使用两个bean类employee和admin。我已使用employee类对象在employee类中设置变量empid。我想将该employee类对象（emp）设置为admin class.but我得到空指针异常在empid领域。

    emp.setEmpid(eid);
    ad.setCourseid(cid);
    ad.setCoursename(cname);
    ad.setParticipants(participants);
    ad.setEmployee(emp);

员工

package entity;





public class Employee 
{

    private int empid;
    private String empname;
    private String password;
    private String designation;
    private String domain;
    private String role;

    private String head;
    private String specialist;

    public int getEmpid() {
        return empid;
    }
    public void setEmpid(int empid) {
        this.empid = empid;
    }
    public String getEmpname() {
        return empname;
    }
    public void setEmpname(String empname) {
        this.empname = empname;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getDesignation() {
        return designation;
    }
    public void setDesignation(String designation) {
        this.designation = designation;
    }
    public String getDomain() {
        return domain;
    }
    public void setDomain(String domain) {
        this.domain = domain;
    }
    public String getRole() {
        return role;
    }
    public void setRole(String role) {
        this.role = role;
    }
    public String getHead() {
        return head;
    }
    public void setHead(String head) {
        this.head = head;
    }
    public String getSpecialist() {
        return specialist;
    }
    public void setSpecialist(String specialist) {
        this.specialist = specialist;
    }
}

管理

package entity;
public class Admin {

    private int courseid;
    private String coursename;
    private int participants;
    private Employee employee;

public Employee getEmployee() {
        return employee;
    }
    public void setEmployee(Employee empid) {
        this.employee = employee;
    }
public int getCourseid() {

        return courseid;
    }
    public void setCourseid(int courseid) {

        this.courseid = courseid;

    }
    public String getCoursename() {
        return coursename;
    }
    public void setCoursename(String coursename) {
        this.coursename = coursename;
    }
    public int getParticipants() {
        return participants;
    }
    public void setParticipants(int participants) {
        this.participants = participants;
    }
}

实际上我想将数据库中的empid作为外键插入，但是由于空指针异常，我不能这样做。

Answer 1

看看这里，在您的管理类中，您正在做这样的事情

public void setEmployee(Employee empid) {
        this.employee = employee;
}

这就像空任务一样，您将员工分配给没有任何效果的员工，总是将空值分配给空值，因为对象的默认值为空

就像

一样

public void setEmployee(Employee empid) {
       this.employee = empid;
}

在另一个类中设置一个类中的变量

1 个答案: