Java做一个增删改查
时间: 2023-10-05 09:04:15 浏览: 112
好的,下面是一个简单的Java增删改查示例:
首先,我们需要创建一个实体类,假设我们要操作一个学生对象,那么可以创建一个名为Student的类:
```java
public class Student {
private int id;
private String name;
private int age;
private String gender;
// 构造方法
public Student(int id, String name, int age, String gender) {
this.id = id;
this.name = name;
this.age = age;
this.gender = gender;
}
// getter和setter方法
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
}
```
接下来,我们需要创建一个DAO(数据访问对象)类,该类中定义了增删改查的方法:
```java
import java.util.ArrayList;
import java.util.List;
public class StudentDAO {
private List<Student> students = new ArrayList<>();
// 添加学生
public void addStudent(Student s) {
students.add(s);
}
// 根据ID删除学生
public void deleteStudent(int id) {
for (Student s : students) {
if (s.getId() == id) {
students.remove(s);
break;
}
}
}
// 修改学生信息
public void updateStudent(Student s) {
for (Student student : students) {
if (student.getId() == s.getId()) {
student.setName(s.getName());
student.setAge(s.getAge());
student.setGender(s.getGender());
break;
}
}
}
// 根据ID查询学生
public Student getStudentById(int id) {
for (Student s : students) {
if (s.getId() == id) {
return s;
}
}
return null;
}
// 查询所有学生
public List<Student> getAllStudents() {
return students;
}
}
```
最后,我们可以在主函数中测试这些方法:
```java
public class Main {
public static void main(String[] args) {
StudentDAO dao = new StudentDAO();
// 添加学生
dao.addStudent(new Student(1, "张三", 18, "男"));
dao.addStudent(new Student(2, "李四", 19, "女"));
dao.addStudent(new Student(3, "王五", 20, "男"));
// 查询所有学生
List<Student> students = dao.getAllStudents();
for (Student s : students) {
System.out.println(s.getId() + " " + s.getName() + " " + s.getAge() + " " + s.getGender());
}
// 根据ID查询学生
Student s = dao.getStudentById(2);
if (s != null) {
System.out.println(s.getId() + " " + s.getName() + " " + s.getAge() + " " + s.getGender());
}
// 修改学生信息
Student updatedStudent = new Student(2, "王麻子", 20, "男");
dao.updateStudent(updatedStudent);
// 删除学生
dao.deleteStudent(1);
}
}
```
通过上述代码,我们就可以实现一个简单的Java增删改查功能了。