疑問 - 如何改成抽象類別

[snoopy]

雖然我不知道為什麼你要這要做
不過很好改

interface Data 
{    
   public void showData();    
} 
interface Test 
{ 
   public void showScore(); 
   public double calcu(); 
} 
abstract class CStu implements Data,Test 
{ 
   protected String id;    // 學號 
   protected String name;  // 姓名  
   protected int mid;      // 期中考成績 
   protected int finl;     // 期末考成績 
   protected int common;   // 平時成績 
        
   public CStu(String s1,String s2,int m,int f,int c) 
   { 
      id=s1; 
      name=s2; 
      mid=m; 
      finl=f;    
      common=c;    
   } 
   public void show() 
   { 
      showData(); 
      showScore(); 
   } 
   public void showScore() 
   { 
      System.out.println("期中考成績:"+mid); 
      System.out.println("期末考成績:"+finl); 
      System.out.println("平時成績:"+common); 
      System.out.println("學期成績:"+calcu()); 
   } 
   public void showData() 
   { 
      System.out.println("學號:"+id); 
      System.out.println("姓名:"+name); 
   } 
   public double calcu() 
   { 
      return (mid*0.3+finl*0.3+common*0.4);       
   } 
} 

class SubClass extends CStu{
	public SubClass(String s1,String s2,int m,int f,int c){
		super(s1,s2,m,f,c);
	}
}

public class App 
{ 
   public static void main(String args[]) 
   { 
      CStu stu=new SubClass("940001","Fiona",90,92,85); 
      stu.show(); 
   } 
}