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Thread: assert() function is not working. Why?

  1. #1
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    Question assert() function is not working. Why?

    The following program is not working as I want. The assert() function is not working while I'm entering a number which is out of range 0-10. Whereas, according to my book, it is working like that:

    Output:
    Enter a number between 0 and 10: 50
    Exception in thread "main" java.lang.AssertionError: bad number: 50
    at AssertionTest.main(AssertTest.java:15)


    But I cannot see the error message above after compiling the program on eclipse and netbeans. I just see that:

    Output:
    Enter a number between 0 and 10: 50
    You entered 50

    What is the problem? Why the function assert is not working?

    import java.util.Scanner;
     
    public class Assertion {
     
        public static void main(String[] args) {
            Scanner input = new Scanner(System.in);
     
            System.out.print("Enter a number between 0 and 10: ");
            int number = input.nextInt();
     
            assert(number >= 0 && number <= 10) : "bad number: " + number; // assert, "bildir" demektir.
     
            System.out.printf("You entered %d\n",number);
        }
     
    }


  2. #2
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    Default Re: assert() function is not working. Why?

    assert is not a function, its a keyword. Its a build in feature that must be enabled before it can be used.

    To enable this feature you have to add the command "-ea" to the argument list when initializing your JVM.
    Your IDE should give you the option to set a Run-Configuration where you can select the JVM commands to be used when testing your application. Make sure to add the command to the correct list.

  3. The Following User Says Thank You to Cornix For This Useful Post:

    hefese (September 7th, 2014)

  4. #3
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    Thumbs up Re: assert() function is not working. Why?

    Thank you so much Cornix. I did it in Eclipse and Netbeans like that:

    In Eclipse:
    Run->Run Configurations->Arguments->VM Arguments-> ....
    I wrote -ea in VM Arguments.

    In Netbeans:
    Run->Set Project Configuration->Customize->VM Options->...
    I wrote -ea in VM Options.

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