Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at Calculator.main(Calculator.java:25) [duplicate]

Question

I wrote this code for a simple calculator and I get this error! Someone help me please!

public class Calculator { 

  public static void main (String[] args) {

    int num1 = Integer.parseInt(args[0]);
    int num2 = Integer.parseInt(args[1]);
    int sum = num1 + num2;
    int sub = num1 - num2;  
    int prod = num1 * num2;
    int quot = num1 / num2;
    int rem = num1 % num2;

    // print the other variables, sub, prod, quot, rem;     
    System.out.println(num1 + " + " + num2 + " = " + sum);      
    System.out.println(num1 + " - " + num2 + " = " + sub);      
    System.out.println(num1 + " * " + num2 + " = " + prod);     
    System.out.println(num1 + " / " + num2 + " = " + quot);     
    System.out.println(num1 + " % " + num2 + " = " + rem);
  }
}

I suggest adding if (args.length != 2) throw new IllegalArgumentException("Expected 2 arguments, but got: " + Arrays.toString(args)) to the start of your main-method. This won't fix your problem, but will give you a better error message ;-). — yankee
– yankee, Commented Sep 23, 2017 at 20:17

OneCricketeer · Accepted Answer · 2017-09-23 20:20:23Z

1

You need to make sure that when the application is started, it is passed two strings that can be parsed as numbers because your code assumes that arguments will have an element at positions 0 and 1. If you don't pass two arguments, then you will get your error.

For example, if calling main from within the program:

Calculator.main(new String[] {"10","20"});

Or, if calling Calculator.class from the command line:

java Calculator 10 20

edited Sep 23, 2017 at 20:20

OneCricketeer

193k20 gold badges146 silver badges276 bronze badges

answered Sep 23, 2017 at 20:12

Scott Marcus

66k6 gold badges54 silver badges81 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

OneCricketeer Over a year ago

You don't typically call main directly. It's passed at the command line

Scott Marcus Over a year ago

@cricket_007 I know, I was just trying to reinforce the point and was adding the command line example at that moment.

K. Lujan Over a year ago

But if I do that, then I get more errors?

Scott Marcus Over a year ago

@K.Lujan Ok, then there are other issues with your code that need to be worked out. Take them one at a time.

Scott Marcus Over a year ago

@cricket_007 Thanks. I'm not a Java guy (I do C#), so I knew what the problem was, but a little rusty on the syntax.

VHS · Accepted Answer · 2017-09-23 20:24:20Z

0

As the exception indicates, your program encountered an Array out of bounds exception when it tried to access an array within index of 0. The only place in your code above where in Array with an index of 0 is being accessed is at the following line

int num1 = Integer.parseInt(args[0]);

So in other words, your program couldn't find 0th index of the args array which means you haven't passed any arguments to your program. Looks like your program two arguments in fact. Run your program the following way if you are using command line

java Calculator 100 200

edited Sep 23, 2017 at 20:24

answered Sep 23, 2017 at 20:21

VHS

10.2k3 gold badges25 silver badges48 bronze badges

Collectives™ on Stack Overflow

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at Calculator.main(Calculator.java:25) [duplicate]

2 Answers 2

5 Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

Comments

Linked

Related