import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.lang.*;

public class Students extends Applet implements ActionListener
{
	Vector StuInf=new Vector();
	StudentInf SI;
	String xm;
	String bj;
	int i,j,xh,cj;
	static int mid;
	Label prompt1=new Label("學生成績管理系統");
	Label prompt2=new Label("			用戶:");
	Label prompt3=new Label("			密碼:");
	Label prompt4=new Label("			班級:");
	Label prompt5=new Label("			成績:");
	TextField input1=new TextField(8);
	TextField input2=new TextField(8);
	TextField input3=new TextField(8);
	TextField input4=new TextField(8);
	Button btn1=new Button("登錄");
	Button btn2=new Button("增加");
	Button btn3=new Button("修改");
	Button btn4=new Button("刪除");
	
	public void init()
	{
		setLayout(new GridLayout(6,3));
		add(new Label());
		add(prompt1);
		add(new Label());
		add(prompt2);
		add(input1);
		add(new Label());
		add(prompt3);
		add(input2);
		add(btn1);
		add(prompt4);
		add(input3);
		add(new Label());
		add(prompt5);
		add(input4);
		add(new Label());
		add(btn2);
		add(btn3);
		add(btn4);
		prompt4.setVisible(false);
		prompt5.setVisible(false);
		input3.setVisible(false);
		input4.setVisible(false);
		btn2.setVisible(false);
		btn3.setVisible(false);
		btn4.setVisible(false);
		btn1.addActionListener(this);
		btn2.addActionListener(this);
		btn3.addActionListener(this);
		btn4.addActionListener(this);
	}
	public void actionPerformed(ActionEvent e)
	{
		if(e.getActionCommand()=="登錄")
		{
			String a,b;
			a=input1.getText();
			b=input2.getText();
			input1.setText("");
			if((a.equals("12")==true)&&(b.equals("12")==true))
			{
				prompt2.setText("			姓名:");
				prompt3.setText("			學號:");	
				prompt4.setVisible(true);
				prompt5.setVisible(true);
				input3.setVisible(true);
				input4.setVisible(true);
				btn2.setVisible(true);
				btn3.setVisible(true);
				btn4.setVisible(true);
				btn3.setEnabled(false);
				btn4.setEnabled(false);
				btn1.setLabel("查詢");
				input1.setText("登錄成功");
				input1.selectAll();
			}
			else
			input2.setText("用戶名或密碼錯");
		}
		if(e.getActionCommand()=="增加")
		{
			boolean scucss=true;
			try
			{
				XingMing();
			}
			catch(EmptyException as)
			{
				input1.setText("姓名不能為空");
				scucss=false;
			}
			try
			{
				xh=Integer.parseInt(input2.getText());
			}
			catch(NumberFormatException m)
			{
				input2.setText("學號為空或格式錯");
				scucss=false;
			}	
			bj=input3.getText();
			try
			{
				ChengJi();
			}
			catch(EmptyException as)
			{
				cj=-1;
			}
			catch(OverException dd)
			{
				input4.setText("應在0-100間");
				scucss=false;
			}
			catch(NumberFormatException cm)
			{
				input4.setText("成績應為數據");
				scucss=false;		
			}
			if(scucss==true)
			{
			SI=new StudentInf(xm,xh,bj,cj);
			Insert(SI);
			}
		}
		if(e.getActionCommand()=="修改")
		{
			xm=input1.getText();
			xh=Integer.parseInt(input2.getText());
			bj=input3.getText();
			cj=Integer.parseInt(input4.getText());
			SI=new StudentInf(xm,xh,bj,cj);
			StuInf.setElementAt(SI, mid);
			btn3.setEnabled(false);
		}
		if(e.getActionCommand()=="刪除")
		{
			StuInf.removeElementAt(mid); 
			btn4.setEnabled(false);
			input1.setText("刪除成功");
			input2.setText("");
			input3.setText("");
			input4.setText("");
		}
		if(e.getActionCommand()=="查詢")
		{
			boolean right=true;
			try
			{
				xh=Integer.parseInt(input2.getText());
			}
			catch(NumberFormatException m)
			{
				input2.setText("學號為空或格式錯");
				right=false;
			}	
			if(right==true)
			{
				search(xh);
				btn3.setEnabled(true);
				btn4.setEnabled(true);
			}
		}
		
	}
	//查找方法
	public void search(int k)
	{
			boolean  exist=false;
			int low=0;
			int high=StuInf.size()-1;
			while(low<=high)
			{
				mid=(high+low)/2;
				StudentInf a1=(StudentInf) StuInf.elementAt(mid);
				if(a1.getStuNo()==k)
				{
					SI=(StudentInf) StuInf.elementAt(mid);
					String x = String.valueOf(SI.getStuNo());
					exist=true;
					input1.setText(SI.getname());
					input1.selectAll();
					input2.setText("0"+x);
					input3.setText(SI.getClassNo());
					if(SI.getLevel()==-1)
						input4.setText("未參加考試");
					else
					{
						String y = String.valueOf(SI.getLevel());
						input4.setText(y);
					}
					break;
				}
				else if(a1.getStuNo()<k)
				low=mid+1;
				else
				high=mid-1;	
			}
			if(exist==false)
			{
				input1.setText("無此學號學生信息");
				input1.selectAll();
			}
	}
//添加方法
	public void Insert(StudentInf q)
	{
		int i=0;
		
		if(StuInf.isEmpty()==true) 
			{
				StuInf.addElement(q);
				input1.setText("");
				input2.setText("");
				input3.setText("");
				input4.setText("");
			}
		else
		{
			StudentInf xh;
			xh=(StudentInf) StuInf.firstElement();
			while(xh.getStuNo()<q.getStuNo())
			{
				i++;
				if(i<StuInf.size())
				xh=(StudentInf) StuInf.elementAt(i);
				else 
				break;
			}			
			if(xh.getStuNo()==q.getStuNo())
			{
				input2.setText("此學生信息已存在");
				input2.requestFocus();
				input2.selectAll();
			}
			else 
			{
				StuInf.insertElementAt(q,i);		
				input1.setText("");
				input2.setText("");
				input3.setText("");
				input4.setText("");
			}
		}		
	}
	
	//異常類
	class OverException extends Exception
	{
		String over;
	}	
	class EmptyException extends Exception
	{
		String empty;
	}
	void XingMing() throws EmptyException
	{
		if((input1.getText()).equals(""))
			throw (new EmptyException());
		else
			xm=input1.getText();
	}
	void ChengJi() throws OverException,EmptyException 
	{
		if((input4.getText()).equals(""))
		throw(new EmptyException());
		else
		cj=Integer.parseInt(input4.getText());
		if(cj<0||cj>100)
		throw (new  OverException());
	}
	
	//學生信息類
	public class StudentInf
	{
		private String name;
		private int StuNo;
		private String ClassNo;
		private int Level;
		StudentInf(String xingming,int xuehao,String banji,int chengji)
		{
			name=xingming;
			StuNo=xuehao;
			ClassNo=banji;
			Level=chengji;
		}
		public int getStuNo()
		{
			return StuNo;
		}
		public String getname()
		{
			return name;
		}
		public String getClassNo()
		{
			return ClassNo;
		}
		public int getLevel()
		{
			return Level;
		}
	}

}