实训JAVA语言设计——类设计训练-CFANZ编程社区

1.三角形类:
   
import java.awt.*; 
   

   
import java.applet.*; 
   

   
class rectangles  //定义 rectangles类
   
{ 
   
      
   
public int Width; 
   
    
   
public int Height; 
   
    
   
public rectangles(int CWidth, int CHeight) //构造方法 
   
{     
   
Width=CWidth; 
   
       
   
Height=CHeight; 
   
    
   
}//构造方法定义毕
   
    
   
public void Showrectangle(Graphics g,int x,int y) 
   
   {  
   
g.drawString("Width:"+Width,x,y); 
   
      
   
g.drawString("Height:"+Height,x,y+20); 
   
  
   
g.drawString("Area:"+Height*Width,x,y+40); 
   
   
   
} 
   

   
} // dogs类定义毕 
   
public class c4_1  extends Applet 
   
{ 
   
     
   
public  void paint(Graphics g) 
   
    
   
{   
   
rectangles myrect=new rectangles(20,30); 
   
          
   
       
   
myrect.Showrectangle(g,25,120); 
   
    
   
} 
   
}  
   
//html文件:
   

   
<html><head><title>applet program</title></head><body><applet code="a.class" 
   
Width=200 height=250></applet></body></html> 
   

   

   

   

   

   

   

   
2.学生信息
   
import java.awt.*; 
   

   
import java.applet. *; 
   

   
class students //定义students类
   

   
{  
   
         
   
//以下三行定义students类的数据成员
   
    
   
public String stu_NO ; 
   
    
   
public String stu_name; 
   
   
   
public int grade1;  
   
public int grade2; 
   
//以下六行是students类的成员方法Showstudent( )的定义
   
    
   
public void Showstudent(Graphics g,int x,int y) 
   
    
   
{ 
   
     
   
g.drawString("stu_N.O:"+stu_NO,x,y); 
   
      
   
g.drawString("stu_name:"+stu_name,x,y+20); 
   
      
   
g.drawString("totalgrade:"+(grade1+grade2),x,y+40); 
   
  
   
 }  
   
//成员方法Showstudent( )定义完成
   
}// students类定义毕 
   
public class c4_2  extends Applet 
   
{ 
   
    
   
public  void paint(Graphics g) 
   
    
   
{ 
   
       
   
//以下为创建对象
   
       
   
students liuxing;  //声明了一个名为liuxing的对象，它属于students类
   
       
   
liuxing=new students( );  //建立lixing对象，为它分配存储空间
   
       
   
students hanfeng=new students( );//声明hanfeng对象的同时建立该对象
   
students yingwei=new students( );//声明yingwei对象的同时建立该对象
   
  
   
students zhaoke=new students( );//声明zhaoke对象的同时建立该对象
   
  
   
students lishu=new students( );//声明lishu对象的同时建立该对象
   
  
   
       
   
//以下几行引用对象的数据成员，将一组值赋给对象的数据成员
   
       
   
liuxing.stu_name="liuxing"; 
   
       
   
liuxing.stu_NO="10010"; 
   
liuxing.grade1=95; 
   
liuxing.grade2=94;  
   
hanfeng.stu_name="hanfeng"; 
   
       
   
hanfeng.stu_NO="10011"; 
   
hanfeng.grade1=85; 
   
hanfeng.grade2=92;  
   
yingwei.stu_name="yingwei"; 
   
       
   
yingwei.stu_NO="10012"; 
   
yingwei.grade1=68; 
   
yingwei.grade2=84;  
   
zhaoke.stu_name="zhaoke"; 
   
       
   
zhaoke.stu_NO="10013"; 
   
zhaoke.grade1=75; 
   
zhaoke.grade2=77;  
   
lishu.stu_name="lishu"; 
   
       
   
lishu.stu_NO="10014"; 
   
lishu.grade1=89; 
   
lishu.grade2=91;       
   
//以下两行引用对象的成员方法
   
       
   
liuxing.Showstudent(g,25,25); 
   
       
   
hanfeng.Showstudent(g,200,25); 
   
yingwei.Showstudent(g,25,120); 
   
zhaoke.Showstudent(g,200,120); 
   
lishu.Showstudent(g,25,240);   } }  
   

   
3.用构造方法写:
   
import java.awt.*; 
   

   
import java.applet.*; 
   
class students  //定义 students类
   
{ 
   
    
   
public String stu_NO ; 
   
    
   
public String stu_name; 
   
   
   
public int grade1;  
   
public int grade2; 
   
public students(String Cstu_NO,String Cstu_name,int Cgrade1,int Cgrade2)   //构造方法 
   
{    
   
stu_NO=Cstu_NO; 
   
      
   
stu_name=Cstu_name; 
   
       
   
grade1=Cgrade1; 
   
  
   
grade2=Cgrade2;   
   
}//构造方法定义毕
   
    
   
public void Showstudent(Graphics g,int x,int y) 
   
    
   
{   
   
g.drawString("stu_NO:"+stu_NO,x,y); 
   
      
   
g.drawString("stu_name:"+stu_name,x,y+20); 
   
      
   
g.drawString("totalgrade:"+(grade1+grade2),x,y+40); 
   
    
   
} 
   

   
} // dogs类定义毕 
   
public class c4_3  extends Applet 
   
{ 
   
     
   
public  void paint(Graphics g) 
   
    
   
{   
   
students liuxing=new students("10010","liuxing",95,94); 
   
       
   
students hanfeng=new students("10011","handeng",85,92); 
   
students yingwei=new students("10012","yingwei",68,84); 
   
  
   
students zhaoke=new students("10013","zhaoke",75,77); 
   
  
   
students lishu=new students("10014","lishu",89,91); 
   

   
liuxing.Showstudent(g,25,25); 
   
       
   
hanfeng.Showstudent(g,200,25); 
   
yingwei.Showstudent(g,25,120); 
   
zhaoke.Showstudent(g,200,120); 
   
lishu.Showstudent(g,25,240);  
   
} 
   
}  
   

   
4. 用pulic类来定义一个无修饰符的static,final类!
   
import java.awt.*; 
   
import java.applet.*; 
   

   
class pp{    
   
static int n=33;     
   
final int nn;   //声明nn,但没有赋初值
   
      
   
final int k=55; //声明k并赋初值40
   
      
   
pp( ) 
   
     
   
{  nn= ++n; }//在构造方法中给nn赋值
   
}  
   
public class c4_4 extends Applet 
   
{ 
   
     
   
public void paint(Graphics g) 
   
    {   
   
pp m1=new pp( );  //创建对象m1，使其静态数据成员nn的值为21
   
         
   
pp m2=new pp( );  //创建对象m2，使其静态数据成员nn的值为22
   
         
   
// m1.nn=90; //这是一个错误的赋值语句，因为nn是标识符常量
   
        
   
g.drawString("m2.nn="+m2.nn,20,30); 
   
        
   
g.drawString("m2.k="+m2.k,20,50); 
   
        
   
g.drawString("m1.nn="+m1.nn,20,70); 
   
        
   
g.drawString("m1.k="+m1.k,20,90); 
   
g.drawString("m1.nn="+m1.nn,20,110);g.drawString("m2.k="+m2.k,20,130);