Modify before asshignment so that we can check input errors

Modify before asshignment so that we can check input errors, etc.. Please refer to the following Java code.

You should add switch, run your programing untill you choose figure==0 (using while loop), cheak input error.

Catch (Exception e) is optional.

import java.util.Scanner;

public class inputError5 {

public static void main(String[] args) {

Scanner consol=new Scanner(System.in);
int choice=0;

while(true){

System.out.println(\"=============================\");
System.out.println(\"= 1. function1 =\");
System.out.println(\"= 2. function2 =\");
System.out.println(\"= 3. function3 =\");
System.out.println(\"=============================\");
System.out.print(\"Select : \");

choice= consol.nextInt();

switch(choice){
case 0: System.out.println(\"Bye!! \");
System.exit(0);
case 1: function1();

break;
case 2: function2();
break;
case 3: function3();
break;
default:System.out.println(\"Wrong number!! Type 1~3 \");
break;
}

} // while
}

public static void function1(){
System.out.println(\"function1\");
}
public static void function2(){
System.out.println(\"function2\");
}

public static void function3(){
System.out.println(\"function3\");
}

}

Solution

Solution:

I am helping you by adding exception handling in this program. please find comments for more details...

package com.nancy.hello;

import java.util.InputMismatchException;
import java.util.Scanner;

public class inputError5 {

   public static void main(String[] args) {

       int choice = 0;

       /**
       * This while loop terminates when user enter value = 0 only.
       */
       while (true) {
           Scanner consol = new Scanner(System.in);

           System.out.println(\"=============================\");
           System.out.println(\"= 1. function1 =\");
           System.out.println(\"= 2. function2 =\");
           System.out.println(\"= 3. function3 =\");
           System.out.println(\"=============================\");
           System.out.print(\"Select : \");
           try {

               choice = consol.nextInt();

               // If user enters negative number then following error will be displayed and loop continues.
               if (choice < 0) {
                   System.out.println(\"Error! Please enter a positive integer value.Type 1~3\");
               } else {
                   switch (choice) {
                   case 0:
                       System.out.println(\"You have entered 0, Bye!! \");
                       System.exit(0); // exiting from program
                   case 1:
                       function1();
                       break;
                   case 2:
                       function2();
                       break;
                   case 3:
                       function3();
                       break;
                   default:
                       System.out.println(\"Wrong number!! Type 1~3 \");
                       break;
                   }
               }
           } catch (InputMismatchException e) {
               System.out.println(\"Input Error! Please enter a positive integer value.Type 1~3\");
               //continue;
           }
       } // while loop ends here
   }

   public static void function1() {
       System.out.println(\"function 1\");
   }

   public static void function2() {
       System.out.println(\"function 2\");
   }

   public static void function3() {
       System.out.println(\"function 3\");
   }
}

Sample run:

=============================
= 1. function1 =
= 2. function2 =
= 3. function3 =
=============================
Select : nancy
Input Error! Please enter a positive integer value.Type 1~3
=============================
= 1. function1 =
= 2. function2 =
= 3. function3 =
=============================
Select : -1
Error! Please enter a positive integer value.Type 1~3
=============================
= 1. function1 =
= 2. function2 =
= 3. function3 =
=============================
Select : 1
function 1
=============================
= 1. function1 =
= 2. function2 =
= 3. function3 =
=============================
Select : 0
You have entered 0, Bye!!