Question

(use java)

Write a program that creates an exception class called StringTooLongException, designed tobe thrown when a string is discoveredthat has too many characters in it. In the main driver of the program, read strings from the user until the user enters “DONE”. If a string is entered that has too many characters (say 20), throw, catch, and handle the exception. The exception is handled by printing an appropriate message, and the programwill continueprocessing more strings.

Answer 1

I have created the StringTooLongException class and also override the toString( ) method. Though I have documented the code still if you have any doubt feel free to comment. I'll try my best to resolve them.

Assumption : For "Done", I am taking it as case insensitive i.e. If user entered "Done" then the program will exit but don't worry if you want it as case sensitive, I've commented the solution(see line 36).

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Code :   Main.java

import java.util.Scanner;
class StringTooLongException extends Exception
{
String str;
public StringTooLongException(String s)
{
// Call constructor of parent Exception
super(s);
str=s;
}
//Override toString method
public String toString()
{
return "String : "+str+" has more than 20 characters";
}
}
public class Main
{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
String s;
int len;
while(true)
{
try
{
//input
System.out.println("\nEnter the String : ");
s=sc.next();
len=s.length();
  
//checking for exception
if(len>20)
throw new StringTooLongException(s);
/*checking if user entered done. This is case insensitive
for case sensitive use s.equals("DONE") */
if(len==4 && s.equalsIgnoreCase("Done"))
break;
//tell the user that string is valid
System.out.println("\n"+s+" is valid.");
}
catch(StringTooLongException ob)
{
System.out.println("\nException Thrown");
System.out.println(ob);
}
}
sc.close();
}
}
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Syntax :

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Output :