test 性别 测试类 statement connect 姓名 oid nag
1. 定义一个 Person 类,包含两个私有的属性(name、age)、一个含参的方法 setValue(int age,String name)、一个不含参方法 setValue() 和一个普通方法 tell()。
定义一个测试类 Test,实例化一个 Person 类的对象,名为 p;对两个属性赋值并输出结果。
- 1 class Person
- 2 {
- 3 private int age;
- 4 private String name;
- 5 public void tell()
- 6 {
- 7System.out.print("姓名:"+name+",年龄:"+age);
- 8 }
- 9 public void setValue(int age,String name)
- 10 {
- 11 this.age=age;
- 12 this.name=name;
- 13 }
- 14 public void setValue()
- 15 {
- 16 this.name="张三";
- 17 this.age=21;
- 18 }
- 19 }
- 20 public class Test
- 21 {
- 22
- 23 public static void main(String[] args)
- 24 {
- 25Person p =new Person();
- 26 p.setValue(21,"Mary");
- 27 p.tell();
- 28 }
- 29}
2. 定义一个 Student 类,继承自 Person 类,含有一个 protected 访问权限的字符型属性 sex,定义 Student 类的构造方法,并覆写父类的 tell() 方法,实现对三个属性的赋值和输出。
- 1 class Person
- 2 {
- 3 private int age;
- 4 private String name;
- 5 public void tell()
- 6 {
- 7System.out.print("姓名:"+name+",年龄:"+age);
- 8 }
- 9 public voidsetValue(int age,String name)
- 10 {
- 11 this.age=age;
- 12 this.name=name;
- 13 }
- 14 public void setValue()
- 15 {
- 16 this.name="张三";
- 17 this.age=21;
- 18 }
- 19 }
- 20 classStudentextends Person
- 21 {
- 22 protected char sex;
- 23 Student(int age,String name,char sex)
- 24 {
- 25 super.setValue(age,name);
- 26 this.sex=sex;
- 27 }
- 28 public void tell()
- 29 {
- 30 super.tell();
- 31System.out.println(",性别:"+sex);
- 32 }
- 33 }
- 34 public class Test
- 35 {
- 36
- 37 public static void main(String[] args)
- 38 {
- 39 Student s = new Student(20,"Mary",'女');
- 40 s.tell();
- 41 }
- 42}
3. 数据库访问的实现
- 1 import java.sql.Statement;
- 2 import java.sql.Connection;
- 3 import java.sql.ResultSet;
- 4 import java.sql.DriverManager;
- 5 import java.sql.SQLException;
- 6 7 public class MySQL 8 {
- 9 public static void main(String[] args) {
- 10 Connection conn = null;
- 11 Statement stmt = null;
- 12 ResultSet rs = null;
- 13
- try 14 {
- 15 Class.forName("com.mysql.jdbc.Driver");
- 16 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/studentInfo", "root", "123456");
- 17 stmt = conn.createStatement();
- 18 rs = stmt.executeQuery("select * from student");
- 19
- while (rs.next()) 20 {
- 21 String no = rs.getString(1);
- 22 String name = rs.getString("sName");
- 23 String sex = rs.getString(3);
- 24 int age = rs.getInt(4);
- 25 String dept = rs.getString("dept");
- 26 System.out.println(no + "__" + name + "__" + sex + " " + age + " " + dept + "__");
- 27
- }
- 28
- }
- 29
- catch(Exception e) 30 {
- 31 e.printStackTrace();
- 32
- }
- 33
- finally 34 {
- 35
- try 36 {
- 37
- if (rs != null) rs.close();
- 38
- if (stmt != null) stmt.close();
- 39
- if (conn != null) conn.close();
- 40
- }
- 41
- catch(SQLException e) 42 {
- 43 e.printStackTrace();
- 44
- }
- 45
- }
- 46
- }
- 47
- }
这是重点!这是重点!这是重点!重要的事情说三遍!!!
总结一下这几节 Java 课的... 重点!!!
来源: http://www.bubuko.com/infodetail-2052054.html