//main.java
import 包.*;
import java.util.*;
public class Main
{
	public static void main(String[] args)
	{
		Scanner in=new Scanner(System.in);
		StuGroup group=new StuGroup(20);  //group可以容納20個(gè)學(xué)生
		int num;  //實(shí)際輸入的學(xué)生信息
		System.out.println("要?jiǎng)?chuàng)建本科生信息表還是研究生信息表？\nA.本科生\tB.研究生");
		Scanner reader = new Scanner(System.in);
		char choice = reader.next().charAt(0);//charAt(index)用于返回索引處的字符
		switch(choice)
		{
			case 'A':
			case 'a':
			System.out.println("請問要輸入多少個(gè)本科生的信息？");
			num = reader.nextInt();
			Student stuB[] = new Undergraduate[num];//stuB[]對象數(shù)組是子類Undergraduate對象的上轉(zhuǎn)型對象
			for(int i=0;i<num;i++)
			{
				System.out.println("請輸入第"+(i+1)+"位學(xué)生的學(xué)號(hào)，姓名，數(shù)學(xué)、計(jì)算機(jī)成績");
				stuB[i] = new Undergraduate(reader.nextInt(), reader.next(),reader.nextDouble(), reader.nextDouble());//從鍵盤輸入學(xué)生信息，并賦值給學(xué)生
				group.addStu(stuB[i]);//參數(shù)為引用類型
			}
			System.out.println("輸入的本科生信息為：");
			group.print();
			group.addStu(new Undergraduate(1312,"shgd",99,98.5));
			group.addStu(new Undergraduate(1316,"ddsa",89,88.5));
			System.out.println("添加后所有本科生的信息為：");
			group.print();
			break;
		case 'B':
		case 'b':
			System.out.println("請問要輸入多少個(gè)研究生的信息？");
			num = reader.nextInt();
			 Student[] stuY = new Postgraduate[num];//stuY[]對象數(shù)組是子類Postgraduate對象的上轉(zhuǎn)型對象
			for(int i=0;i<num;i++)
			{
				System.out.println("請輸入第"+(i+1)+"位學(xué)生的學(xué)號(hào)，姓名，數(shù)學(xué)、計(jì)算機(jī)成績，導(dǎo)師和研究方向，以空格隔開");
				stuY[i] = new Postgraduate(reader.nextInt(), reader.next(),reader.nextDouble(), reader.nextDouble(),reader.next(),reader.next());
				group.addStu(stuY[i]);
			}
			System.out.println("輸入的研究生信息為：");
			group.print();
			group.addStu(new Postgraduate(1312,"shgd",99,98.5,"xyy","os"));
			group.addStu(new Postgraduate(1316,"ddsa",89,88.5,"wcl","rgzn"));
			System.out.println("添加后所有研究生信息為：");
			group.print();
			break;
		default:
			System.out.println("輸入錯(cuò)誤！??！");
			break;
		}
		System.out.println("刪除第幾個(gè)同學(xué)？");
		group.removeStu(reader.nextInt());
		System.out.println("最新的學(xué)生信息為：");
		group.print();
		group.sort(1);
		group.print();//按照數(shù)學(xué)成績排序后輸出
		group.sort(2);
		group.print();//按照計(jì)算機(jī)成績排序后輸出
		in.close();
	}
}

//Mygroup.java
package 包;
//接口MyGroup的聲明。
interface Mygroup
{
	boolean addStu(Student x);
	Student removeStu(int index);
	void sort(int x);
}

//Student.java
package 包;
public abstract class Student 
{
    //抽象學(xué)生類的屬性有學(xué)號(hào)（int）,姓名（String）,數(shù)學(xué)成績（double），計(jì)算機(jī)成績（double）
	int num;
	String name;
	double mathScore;
	double computerScore;
    //【構(gòu)造方法】 
	Student(int num,String name,double mathScore,double computerScore)
	{
		this.num = num;
		this.name = name;
		this.mathScore = mathScore;
		this.computerScore = computerScore;
	}
	public void getNum(int num) 
	{
		this.num = num;
	}
	public int setNum()
	{
		return this.num;
	}
	public void getName(String name) 
	{
		this.name = name;
	}
	public String setName()
	{
		return this.name;
	}
	public void getMathScore(double mathScore)
	{
		this.mathScore = mathScore;
	}
	public double setMathScore()
	{
		return this.mathScore;
	}
	public void getComputerScore(double computerScore)
	{
		this.computerScore =computerScore;
	}
	public double setComputerScore()
	{
		return this.computerScore;
	}
   abstract void print(); //抽象方法，子類要實(shí)現(xiàn)這個(gè)方法，也就是輸出學(xué)生的信息
}

//Postgraduate.java
package 包;
//創(chuàng)建源程序Postgraduate.java，其中的類Postgraduate繼承源程序Student.java中的抽象類Student，實(shí)現(xiàn)其中的抽象方法print( )，并且，在父類的基礎(chǔ)上增加兩個(gè)新的屬性：導(dǎo)師和研究方向。
public class Postgraduate extends Student{
	
	String teacher;
	String direction;
	public Postgraduate(int num, String name, double mathScore, double computerScore,String teacher,String direction) 
	{
		super(num, name, mathScore, computerScore);//子類使用super調(diào)用父類的構(gòu)造方法
		this.teacher = teacher;
		this.direction = direction;
	}
	void getTeacher(String teacher)
	{
		this.teacher =teacher;
	}
	String setTeacher()
	{
		return this.teacher;
	}
	void getDirection(String direction)
	{
		this.direction =direction;
	}
	String setDirection()
	{
		return this.direction;
	}
	void print( )//子類實(shí)現(xiàn)抽象類的方法
	{
		System.out.println("研究生學(xué)生信息為："+"學(xué)號(hào)："+setNum()+",姓名："+setName()+",數(shù)學(xué)成績："+setMathScore()+",計(jì)算機(jī)成績："+setComputerScore()+"導(dǎo)師："+setTeacher()+",研究方向："+setDirection());
	}

}

//Undergraduate.java
package 包;
//創(chuàng)建源程序Undergraduate.java，其中的類Undergraduate繼承源程序Student.java中的抽象類Student，實(shí)現(xiàn)其中的抽象方法print( )。
public class Undergraduate extends Student{
	public Undergraduate(int num, String name, double mathScore, double computerScore) {
		super(num, name, mathScore, computerScore);//子類使用super調(diào)用父類的構(gòu)造方法
	}
	 void print() 
	 {
		System.out.println("本科生信息："+"學(xué)號(hào)："+setNum()+" ,姓名："+setName()+" ,數(shù)學(xué)成績："+setMathScore()+" ,計(jì)算機(jī)成績："+setComputerScore());
	}
}

//StuGroup.java
package 包;

public class StuGroup implements Mygroup
{
	 private Student[] stu;
	 private int length;   //實(shí)際容量
	
	 public StuGroup(int len)
	{
		  stu = new Student[len];
	}
	
	private boolean isOverflow()    //輔助方法，判斷數(shù)組是否溢出
	{
		if(this.length<stu.length)
			return false;
		else
			return true;
	}
	
	public boolean isEmpty()    //判斷數(shù)組是否為空
	{
		return this.length==0;
	}
	
	public boolean addStu(Student x)  //添加學(xué)生信息
	{
		if(isOverflow())
			return false;
		stu[length++]=x;
		return true;
	}
	
	public  Student removeStu(int index)  //刪除指定位置的學(xué)生信息
	{
		if(isEmpty())
		{
			System.out.println("學(xué)生表空的~~~刪除失敗~~~~");
			return null;
		}
		Student temp=stu[index-1];
		for(int i=index-1;i<this.length-1;i++)
		{
			stu[i]=stu[i+1];
		}
		this.length--;
		return temp;
	}
	
	
	 public void sort(int x)   //按照成績排序，參數(shù)1按數(shù)學(xué)排序，參數(shù)2按計(jì)算機(jī)排序
	{
		if(x==1)
		{
			for(int i =0;i<length-1;i++)
				for(int j =0;j<length-i-1;j++)//冒泡排序
				{
					if(stu[j].setMathScore()<stu[j+1].setMathScore())
					{
						Student temp;//聲明一個(gè)對象（引用），用于交換
						temp =stu[j+1];
						stu[j+1] = stu[j];
						stu[j] = temp;
					}
				}
			System.out.println("按數(shù)學(xué)成績降序排列為：");
	
	     }
		else if(x==2)
		{
			for(int i =0;i<length-1;i++)
				for(int j =0;j<length-i-1;j++)
				{
					if(stu[j].setComputerScore()<stu[j+1].setComputerScore())
					{
						Student temp;
						temp =stu[j+1];
						stu[j+1] = stu[j];
						stu[j] = temp;
					}
				}
			System.out.println("按計(jì)算機(jī)成績降序排名：");
		}
     }	
	public void print()
	{
		                 
		for(int i =0;i<length;i++)
			stu[i].print();//調(diào)用Student子類的print（）方法
	}
		
}