java assert not throwing exception

Question

I am checking if number is between 1-10 using assert, but if I enter a number beyond 10 it still gives me the result rather than throwing an exception. What am I doing wrong?

import java.util.Scanner;

public class xina {
    public static void main(String[] args) throws Exception {

        System.out.println("enter any number");

        Scanner input = new Scanner(System.in);

        int num = input.nextInt();

        assert ( num >= 0 && num <= 10 ) : "bad number: " + num;
        System.out.println("You entered " + num);
    }
}

Did you enable assertions with `-ea`? – Absurd-Mind Jul 11 '14 at 07:04 — Absurd-Mind, Jul 11 '14 at 07:04

ApproachingDarknessFish · Answer 1 · 2014-07-11T07:13:47.393

4

Assertions are disabled by default in java. You need to manually enable them by adding -ea to your command-line arguments when you invoke the java compiler. I can't tell you how to do this without knowing what compiler/environment you're using.

Edit:

In eclipse, go to the run menu, and click on run configurations. Select the arguments tab and type -ea into the VM arguments.

edited Jul 11 '14 at 07:13

answered Jul 11 '14 at 07:04

ApproachingDarknessFish

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@Nomad instructions added. – ApproachingDarknessFish Jul 11 '14 at 07:09

score 1 · Answer 2 · answered Jul 11 '14 at 07:04

1

Are assertions enabled (-ea flag when running program) ?

By default, they are not enabled by the virtual machine.

answered Jul 11 '14 at 07:04

Baptiste Wicht

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score 1 · Answer 3 · edited May 23 '17 at 12:34

1

This article shows you how to do it in eclipse. Could be helpful for you

Go to Run->run configuration
select java application in left nav pan.
right click and select New.
select Arguments tab
Add -ea in VM arguments.

How to enable the Java keyword assert in Eclipse program-wise?

edited May 23 '17 at 12:34

Community

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answered Jul 11 '14 at 07:07

Arno_Geismar

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java assert not throwing exception

3 Answers3