WAP read charator form file and Display if charator if is alphabet then reverse it Case wheter it digit or Space

/*WAP read charator form file and Display
if charator if is alphabet then reverse it Case
wheter it digit or Space
*/
import java.io.*;
class Slip1
{
public static void main(String args[])throws IOException
{
int c;
try
{
FileReader fr=new FileReader("a.txt");
while((c=fr.read())!=-1)
{
if(c>=65&&c<=90)
{
c=c+32;
System.out.print((char)c);
}
else if(c>=97&&c<=122)
{
c=c-32;
System.out.print((char)c);
}
else if((char)c==' ')
{
System.out.print("Space"+' ');
}
else if(c>=48&&c<=57)
{
System.out.print("Digit"+(char)c+' ');
}
else
{
System.out.print((char)c);
}

}
fr.close();
}catch(Exception e)
{
System.out.println(e);
}
}
}
/*Output:-
a.txt
Shinde Sachinde 9767@gmail.com
RS1234
D:\javapro\file>javac Slip1.java
D:\javapro\file>java Slip1
sHINDESpace sACHINSpace Digit9 Digit7 Digit6 Digit7 @GMAIL.COM
rsDigit1 Digit2 Digit3 Digit4
*/