Student marks details

import java.io.*;
class stud
{
int no;
int r_no;
String nm;
String sub[]=new String[5];
int subm[]=new int[5];
float per;
int sn;
String grd;
stud(){}
void disp()
{
System.out.print(r_no+"\t"+nm+"\t");
for(int j=0;j<3;j++)
{
System.out.print(subm[j]+"\t");
}
for(int j=0;j<3;j++)
{
System.out.print(grd+"\t");
}
System.out.println(per);
}
}
class Main
{
public static void main(String args[])
{
try
{
DataInputStream ds=new DataInputStream(System.in);

int ch=1;

stud s1[]=new stud[10];

while(ch!=0)
{
System.out.println("\n1.Student Entry ");
System.out.println("2.Student Deatil");
System.out.println("3.Student search ");
System.out.println("4.subject wise ");
System.out.println("0.EXIT ");
System.out.print("\n Enter Your Choice : ");
String s=ds.readLine();
ch=Integer.parseInt(s);
switch(ch)
{
case 1:
System.out.print("Enter no of Students ");
s=ds.readLine();
int n=Integer.parseInt(s);
System.out.print("Enter no of Subjects ");
s=ds.readLine();
int sn=Integer.parseInt(s);
int ans=0;
for(int i=0;i
{
s1[i]=new stud();
System.out.print("Enter stud Roll_no : ");
s=ds.readLine();
s1[i].r_no=Integer.parseInt(s);
s1[i].no=n; //important
System.out.print(s1[i].r_no + ". Enter Name : ");
s1[i].nm=ds.readLine();
}
for(int j=0;j
{
System.out.println("Enter Sub name : ");
s1[0].sub[j]=ds.readLine();
}
for(int i=0;i
{
System.out.println("Enter Marks for"+s1[i].r_no+": ");
for(int j=0;j
{
System.out.print(s1[0].sub[j]+" Marks : ");
s=ds.readLine();
s1[i].subm[j]=Integer.parseInt(s);
ans+=s1[i].subm[j];
}
s1[i].per=(float)ans/sn;
ans=0;
}
s1[0].sn=sn;
break;
case 2:
System.out.println("R_no Name "+s1[0].sub[0]+"\t"+s1[0].sub[1]+"\t"+s1[0].sub[2]+"\t"+"Grade percantage");
System.out.println("-----------------------------------------------------------------");
for(int i=0;i
{
s1[i].disp();
}

break;
case 3:
System.out.print("Enter the r_no for search ");
s=ds.readLine();
boolean b=true;
int search=Integer.parseInt(s);
for(int i=0;i
{
if(search==s1[i].r_no)
{
s1[i].disp();
b=false;
}
}
if(b) System.out.println("Match not found\n");
break;
case 4:
System.out.print("Enter the sub_name : ");
String srch=ds.readLine();
b=false;
for(int j=0;j
{
if(srch==s1[0].sub[j])
{
b=true;

for(int i=0;i
{
System.out.print("E");
if((s1[i].subm[j])>=85)
{
s1[i].grd="AA";
}
if((s1[i].subm[j])>=70)
{
s1[i].grd="AB";
}
if((s1[i].subm[j])>=60)
{
s1[i].grd="BC";
}
if((s1[i].subm[j])>=50)
{
s1[i].grd="CC";
}
}
break;
}
}
for(int i=0;i
{
s1[i].disp();
}
if(b) System.out.println("Match not found\n");
break;
case 0:
break;
}
}
}
catch(IOException e)
{
System.out.println(e);
}
}
}