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Simple Java addition calculator
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simplecalculatoradditionjava
Problem
I made this simple addition calculator in Java and I'm wondering how I can improve it.
package com.craftxbox.main;
import java.util.Scanner;
public class Main {
public static void main(String[] args){
int inInt1;
int inInt2;
int outInt;
@SuppressWarnings("resource")
Scanner in = new Scanner(System.in);
inInt1 = in.nextInt();
inInt2 = in.nextInt();
outInt = inInt1 + inInt2;
System.out.println(outInt);
}
}Solution
You have written some good code, but what if the user does not enter a number, but makes a mistakes? You can, and should, catch that error. What about this:
}
I think a try - catch - finally is a great way of getting user input. This way your problem of the Scanner not being closed, is solved. If this is a little over you head right now, don't worry. It does what it says: we "try" the code in the try block, but if something goes wrong, in this case a "Inputmismatchexception", which means if the user inputs something wrong, we catch it and we display a message saying something went wrong.
Note that I have also changed the variable names. By reading the name, you should immediately know what it is and so names like firstNum and answer are a little better than inInt1 and stuff.
Hope you're still with me. If something is not clear, please feel free to ask some more questions. I myself am a beginner to Java and programming in general and this is the first question I answered.
import java.util.InputMismatchException;
import java.util.Scanner;
public class Calculator
{
static Scanner scanner;
public static void main(String args[])
{
try
{
scanner = new Scanner(System.in);
double firstNum, secondNum, answer;
System.out.println("Enter your first number: ");
firstNum = scanner.nextDouble();
System.out.println("Enter your second number: ");
secondNum = scanner.nextDouble();
answer = firstNum + secondNum;
System.out.println(answer);
}
catch (InputMismatchException e)
{
System.out.println("Invalid input");
}
finally
{
scanner.close();
}
}}
I think a try - catch - finally is a great way of getting user input. This way your problem of the Scanner not being closed, is solved. If this is a little over you head right now, don't worry. It does what it says: we "try" the code in the try block, but if something goes wrong, in this case a "Inputmismatchexception", which means if the user inputs something wrong, we catch it and we display a message saying something went wrong.
Note that I have also changed the variable names. By reading the name, you should immediately know what it is and so names like firstNum and answer are a little better than inInt1 and stuff.
Hope you're still with me. If something is not clear, please feel free to ask some more questions. I myself am a beginner to Java and programming in general and this is the first question I answered.
Code Snippets
import java.util.InputMismatchException;
import java.util.Scanner;
public class Calculator
{
static Scanner scanner;
public static void main(String args[])
{
try
{
scanner = new Scanner(System.in);
double firstNum, secondNum, answer;
System.out.println("Enter your first number: ");
firstNum = scanner.nextDouble();
System.out.println("Enter your second number: ");
secondNum = scanner.nextDouble();
answer = firstNum + secondNum;
System.out.println(answer);
}
catch (InputMismatchException e)
{
System.out.println("Invalid input");
}
finally
{
scanner.close();
}
}Context
StackExchange Code Review Q#100953, answer score: 5
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