try catch blocks not able to figure out catch java - try-catch

Question

SORRY ABOUT FORMATTING. i am trying to determine if the grade is a passing, failing, or invalid grade. however i can't figure out how to catch the error.
EDIT: 70-100 OR "s" or "S" = pass; 0-69 OR u or U = retake; everything else = invalid.
This is my code:
import java.util.*;
public class Demo
{
public static void main(String [] args)
{
Scanner kb = new Scanner(System.in);
String total="";
System.out.println("enter grade");
total = kb.nextLine();
System.out.println(evaluateGrade(total));
}
public static String evaluateGrade(String expr)
{
String result ="";
boolean invalid = false;
int grade = Integer.parseInt(expr);
try{
if((grade <100 && grade >=70) || (expr.equalsIgnoreCase("s"))
{
result ="pass";
}
else if((grade <70 && grade >0)|| expr.equalsIgnoreCase("u"))
{
result ="retake";
}
else
{result="invalid";
}
} catch (Exception e)
{
}
return result;
}
}

Answer 1

This is my code:
import java.util.*;
class Demo{
public static void main(String [] args){
Scanner kb = new Scanner(System.in);
System.out.println("enter grade");
System.out.println(evaluateGrade(kb.next()));
kb.close(); // You need to ".close" your stuff
}
public static String evaluateGrade(String expr){
String result ="";
// boolean invalid = false; <--- This is not necessary
if(expr.equalsIgnoreCase("s")){
return "pass";
}
if(expr.equalsIgnoreCase("u")){
return "retake";
}
try{ // Try to get a Integer on "grade"
Integer grade = Integer.valueOf(expr);
if( (grade <= 100 && grade >=70)){ // 70 <= grade <= 100, and you forgot the ')'
result ="pass";
}
else if((grade <70 && grade >=0)){ // 0 <= grade < 70
result ="retake";
}
else{
result="invalid";
}
}
catch(NumberFormatException e){ // If "grade" is not a number, then you have this line
System.err.println("Your grade must be a NUMBER between 0 and 100.");
return "invalid"; // Return something to keep going with your code
}
return result;
}
}
If you're not understanding what is happening with your code, write it down on the paper.
Have a good day!