總結一下這幾節Java課的...重點!!!
阿新 • • 發佈:2017-05-03
nds test 性別 測試類 statement connect 姓名 oid nag
1.定義一個Person類,包含兩個私有的屬性(name、age)、一個含參的方法setValue(int age,String name)、一個不含參方法setValue()和一個普通方法tell()。
定義一個測試類Test,實例化一個Person類的對象,名為p;對兩個屬性賦值並輸出結果。
1 class Person 2 { 3 private int age; 4 private String name; 5 public void tell() 6 { 7 System.out.print("姓名:"+name+",年齡:"+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="張三"; 17 this.age=21; 18 } 19 } 20 public class Test 21 { 22 23 public static void main(String[] args)24 { 25 Person p = new Person(); 26 p.setValue(21,"Mary"); 27 p.tell(); 28 } 29 }
2.定義一個Student類,繼承自Person類,含有一個protected訪問權限的字符型屬性sex,定義Student類的構造方法,並覆寫父類的tell()方法,實現對三個屬性的賦值和輸出。
1 class Person 2 { 3 private int age; 4 private String name; 5 publicvoid tell() 6 { 7 System.out.print("姓名:"+name+",年齡:"+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="張三"; 17 this.age=21; 18 } 19 } 20 class Student extends 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(); 31 System.out.println(",性別:"+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.數據庫訪問的實現
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 }
這是重點!這是重點!這是重點!重要的事情說三遍!!!
總結一下這幾節Java課的...重點!!!