Assert error in java

Question

probably newbie error here. I copied the assert code directly from the book, but the AssertionError isn't being thrown. If I enter a value lower than 0or higher than 10 execution continues normally.

import java.util.Scanner;

public class AssertExample
{
    public static void main(String[] args)
    {
        Scanner scanner = new Scanner(System.in);

        System.out.print("enter a number between 0 and 10: ");
        int number = scanner.nextInt();

        assert (number >= 0 && number <= 10) : "bad number: " + number;

        System.out.println("You entered " + number);
        scanner.close();
    }
}

enter a number between 0 and 10: -3
You entered -3

possible duplicate [how to enable java keyword assert in Eclipse in program wise?](http://stackoverflow.com/questions/11415160/how-to-enable-java-keyword-assert-in-eclipse-in-program-wise) — Reimeus, Dec 25 '13 at 00:13
Don't use `assert` to validate user input since they're not guaranteed to run: http://stackoverflow.com/a/298973/20394 — Mike Samuel, Dec 25 '13 at 00:15

score 3 · Accepted Answer · answered Dec 25 '13 at 00:09

3

AssertionError isn't being thrown.

Add -ea (enabling assertions) to the Java command arguments when running your application.

answered Dec 25 '13 at 00:09

Adam Siemion

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score 1 · Answer 2 · answered Dec 25 '13 at 00:09

1

You must run the program with assertions enabled.

java -ea[:<packagename>...|:<classname>]

answered Dec 25 '13 at 00:09

adarshr

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Assert error in java

2 Answers2