/*學生信息管理系統，實現學生信息：  *增加 int[] a=new int[9]  *刪除  *查找  *更改  */ import java.util.Scanner;//導入java輸入流 import java.lang.*; import java.io.*; class Student {   private static Student[] s=new Student[2];   int n=0;   private String name;   private int num;   private String classAge;      public void judge()throws IOException   {     int i;     char ch;     String str;     Scanner In=new Scanner(System.in);     if(n==0)     {       System.out.print("你還沒有錄入任何學生，是否錄入(Y/N):");       str=In.next();       ch=str.charAt(0);       while(ch!='Y'&&ch!='y'&&ch!='N'&&ch!='n')       {         System.out.print("輸入有誤，請重新輸入:");         str=In.next();         ch=str.charAt(0);       }       if(ch=='Y'||ch=='y')       {         this.add();       }       if(ch=='N'||ch=='n')       {         this.menu();       }     }   }      public void menu()throws IOException//定義菜單函數   {     int a;//定義switch語句變量     Scanner in=new Scanner(System.in);//實例化輸入流對象     System.out.println("*********學生信息管理系統功能表*********");     System.out.println("*****      1.增加       *****");     System.out.println("*****      2.顯示       *****");     System.out.println("*****      3.修改       *****");     System.out.println("*****      4.刪除       *****");     System.out.println("*****      5.查看       *****");     System.out.println("*****      0.退出       *****");     System.out.println("****************************************");     System.out.print("請選擇(0~5):");     a=in.nextInt();     while(a<0||a>5)     {       System.out.print("輸入超出范圍，請重新輸入:");       a=in.nextInt();     }     switch(a)     {       case 1:this.add();break;       case 2:this.show();break;       case 3:this.modif();break;       case 4:this.delete();break;       case 5:this.look();break;       case 0:System.exit(0);break;     }         }      public void add()throws IOException//定義增加函數   {     String str,str1,str2;     int i,num1,t=1;     char ch,ch1;     FileWriter fw=new FileWriter("F://javaFile//student.txt",true);     fw.write("       錄入的學生信息列表/r/n/r/n學號   姓名   班級/r/n");     Scanner In=new Scanner(System.in);     while(t==1)     {       System.out.print("請輸入學生學號:");       num1=In.nextInt();       for(i=0;i<n;i++)       {         while(s[i].num==num1)         {           System.out.println("已存在此學號，請重新輸入");           System.out.print("請輸入學號:");           num1=In.nextInt();         }       }       s[n].num=num1;       str2=String.valueOf(num1);       fw.write(str2+"  ");       System.out.println();       System.out.print("請輸入學生姓名:");       s[n].name=In.next();       fw.write(s[n].name+"   ");       System.out.println();       System.out.print("請輸入學生班級:");       s[n].classAge=In.next();       fw.write(s[n].classAge+"/r/n");       ++n;       fw.close();        System.out.println();       System.out.print("是否繼續添加(Y/N)");       str=In.next();       ch=str.charAt(0);       while(ch!='N'&&ch!='n'&&ch!='Y'&&ch!='y')       {         System.out.print("輸入有誤，請重新輸入:");         str=In.next();         ch=str.charAt(0);       }       if(ch=='N'||ch=='n')       {         break;       }     }     System.out.println();     System.out.print("是否返回主菜單(Y/N)");     str1=In.next();     ch1=str1.charAt(0);     while(ch1!='Y'&&ch1!='y'&&ch1!='N'&&ch1!='n')     {       System.out.print("輸入有誤，請重新輸入:");       str1=In.next();       ch1=str1.charAt(0);     }     if(ch1=='Y'||ch1=='y')     {       this.menu();     }     if(ch1=='N'||ch1=='n')     {       System.out.println("正在退出...謝謝使用!");       System.exit(0);     }   }      public void show()throws IOException   {     int i;     this.judge();       System.out.println("本次操作共錄入"+n+"位學生!");     System.out.println("你錄入的學生信息如下:");     System.out.println();     System.out.println("學號/t/t姓名/t班級");     for(i=0;i<n;i++)                 {       System.out.println(s[i].num+"    "+s[i].name+"   "+s[i].classAge);     }     System.out.println("系統返回主菜單!");     this.menu();   }      public void delete()throws IOException//刪除信息功能實現 注：本功能暫時不具備可擴展性   {     this.judge();     int j=0,t=0,k=0,num1;     char ch;     String str;     Scanner pin=new Scanner(System.in);     System.out.print("請輸入要刪除的學號:");     num1=pin.nextInt();     for(j=0;j<n;j++)     {       if(s[j].num==num1)       {         k=1;         t=j;       }     }     if(k==0)     {       System.out.println("對不起！你要刪除的學號不存在！");       System.out.println("系統將返回主菜單！");       this.menu();     }     if(k==1)     {       System.out.println("你要刪除的學生信息如下:");//打印管理員要刪除的學生信息       System.out.println("學號/t姓名/t班級");//本功能暫時不備擴展性       System.out.println(s[t].num+"   "+s[t].name+"   "+s[t].classAge);       System.out.println();       System.out.print("你確定要刪除(Y/N):");       str=pin.next();       ch=str.charAt(0);       while(ch!='Y'&&ch!='y'&&ch!='N'&&ch!='n')       {         System.out.print("輸入有誤，請重新輸入:");         str=pin.next();         ch=str.charAt(0);       }       if(ch=='N'||ch=='n')       {         System.out.println();         System.out.println("系統返回主菜單！");         this.menu();       }       if(ch=='Y'||ch=='y')       {         for(j=t;j<n-1;j++)         {           s[j]=s[j+1];         }         n--;         System.out.println("數據成功刪除!");         System.out.println("系統返回主菜單!");         this.menu();       }     }   }      public void look()throws IOException   {     FileReader fr=new FileReader("F://javaFile//student.txt");     int a;     while((a=fr.read())!=-1)     {       System.out.print((char)a);     }     fr.close();     System.out.println("系統返回主菜單！");     System.out.println();     this.menu();   }      public void modif()throws IOException   {     this.judge();     int j=0,t=0,k=0,num2,num3,moi,c=1;     char ch;     String str,str1,str2;     Scanner pin=new Scanner(System.in);     System.out.print("請輸入要修改的學號:");     num2=pin.nextInt();     for(j=0;j<n;j++)     {       if(s[j].num==num2)       {         k=1;         t=j;       }     }     if(k==0)     {       System.out.println("對不起！你要修改的學號不存在！");       System.out.println("系統將返回主菜單！");       this.menu();     }     if(k==1)     {       System.out.println("你要修改的學生信息如下:");//打印管理員要刪除的學生信息       System.out.println("學號/t姓名/t班級");//本功能暫時不備擴展性       System.out.println(s[t].num+"   "+s[t].name+"   "+s[t].classAge);       System.out.println();       System.out.print("你確定要修改(Y/N):");       str=pin.next();       ch=str.charAt(0);       while(ch!='Y'&&ch!='y'&&ch!='N'&&ch!='n')       {         System.out.print("輸入有誤，請重新輸入:");         str=pin.next();         ch=str.charAt(0);       }       if(ch=='N'||ch=='n')       {         System.out.println();         System.out.println("系統返回主菜單！");         this.menu();       }       while(c==1)       {         if(ch=='Y'||ch=='y')         {           System.out.println("****************************************");           System.out.println("*****     1.修改學號      *****");           System.out.println("*****     2.修改班級      *****");           System.out.println("*****     3.修改姓名      *****");           System.out.println("****************************************");           System.out.print("請選擇:");           moi=pin.nextInt();           switch(moi)           {             case 1:System.out.print("請輸入新的學號:");num3=pin.nextInt();s[t].num=num3;break;             case 2:System.out.print("請輸入新的班級:");str1=pin.next();s[t].classAge=str1;break;             case 3:System.out.print("請輸入新的姓名:");str2=pin.next();s[t].name=str2;break;           }           System.out.println("數據已成功修改！");         }         System.out.print("是否繼續修改(Y/N)");         str=pin.next();         ch=str.charAt(0);         System.out.println();         while(ch!='Y'&&ch!='y'&&ch!='N'&&ch!='n')         {           System.out.print("輸入有誤，請重新輸入:");           str=pin.next();           ch=str.charAt(0);         }         if(ch=='N'||ch=='n')         {           break;         }       }       }     System.out.println();     System.out.println("系統返回主菜單！");     this.menu();   }      public static void main(String[] args)throws IOException   {       Student stu=new Student();     for(int i=0;i<2;i++)     {       s[i]=new Student();     }     stu.menu();   } }