Programming Forums > Application Development > Java

357mag · Jul 31st, 2007, 12:57 AM

I don't know if any of you guys have used Netbeans or Java Studio Creator, but I'm experimenting with both. I've got this program that inputs two integers, computes the sum, and displays the result:

(Toggle Plain Text)

public class HelloWorld
{
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        
        int x;
        int y;
        
        System.out.println("Enter a value for x: ");
        
        x = input.nextInt();
        System.out.println("Enter a value for y: ");
        y = input.nextInt();
        
        int sum = x + y;
        
        System.out.println("The sum is: " + sum);               
    }
}

What I can't figure out is every time I re-run the program, the previous integer is still sitting in the input box. Let's say I run the program and the first integer I enter is 3. Then I hit the Enter key to send it along. Then for thte second integer I hit 9. Then I hit the Enter key to send it along. The program displays 12 and I'm done.

Now I want to run the program again, and when I hit the Run button, the number 9 is still sitting in the input box. This is quite annoying. It shouldn't be there. Seems to me when you re-run the program the box should be clear, ready to accept new input.

By the way, this is not a GUI program, this is a console program. But there is a long input box on the bottom of the IDE window when you write a program that uses a scanner to get input from the keyboard.

357mag · Jul 31st, 2007, 1:09 AM

Well I think I may have found a way to fix it. If I go into the Build menu before each new run, and hit Clear and Build, then re-run the program it seems to work.

But you know if you remove the println statements and change them to just print, it doesn't show up on the output until the whole program is done. In other words, when you use println("Enter a value for x: ) it will show on the output window:

Enter a value for x:

But if you remove the println and just code it System.out.print("Enter a value for x: ")

That sentence doesn't show up at all in the output window. You can still enter in two values for the variables, but the strings and the result will not show up until the program is completely done executing.

mrynit · Jul 31st, 2007, 3:00 AM

what IDE are you using? try running the program from console.

357mag · Jul 31st, 2007, 6:06 AM

The situation happens in both Netbeans and Sun Java Studio Creator. It doesn't happen in JDeveloper or JCreator.

DaWei · Jul 31st, 2007, 6:28 AM

It's the same problem that was pointed out to you in your "Can't make the Scanner thing work" post. Consequently, the answer is the same.

casesensitive · Nov 1st, 2007, 9:28 PM

System.out.flush()

Jul 31st, 2007, 12:57 AM	#1
357mag Hobbyist Programmer Join Date: Mar 2005 Posts: 148 Rep Power: 4	Clearing the input box I don't know if any of you guys have used Netbeans or Java Studio Creator, but I'm experimenting with both. I've got this program that inputs two integers, computes the sum, and displays the result: (Toggle Plain Text) public class HelloWorld { public static void main(String[] args) { Scanner input = new Scanner(System.in); int x; int y; System.out.println("Enter a value for x: "); x = input.nextInt(); System.out.println("Enter a value for y: "); y = input.nextInt(); int sum = x + y; System.out.println("The sum is: " + sum); } } public class HelloWorld { public static void main(String[] args) { Scanner input = new Scanner(System.in); int x; int y; System.out.println("Enter a value for x: "); x = input.nextInt(); System.out.println("Enter a value for y: "); y = input.nextInt(); int sum = x + y; System.out.println("The sum is: " + sum); } } What I can't figure out is every time I re-run the program, the previous integer is still sitting in the input box. Let's say I run the program and the first integer I enter is 3. Then I hit the Enter key to send it along. Then for thte second integer I hit 9. Then I hit the Enter key to send it along. The program displays 12 and I'm done. Now I want to run the program again, and when I hit the Run button, the number 9 is still sitting in the input box. This is quite annoying. It shouldn't be there. Seems to me when you re-run the program the box should be clear, ready to accept new input. By the way, this is not a GUI program, this is a console program. But there is a long input box on the bottom of the IDE window when you write a program that uses a scanner to get input from the keyboard.

Jul 31st, 2007, 3:00 AM	#3
mrynit Hobbyist Programmer Join Date: Mar 2006 Location: WA, USA Posts: 332 Rep Power: 3	what IDE are you using? try running the program from console. __________________ i dont know much about programming but i try to help

Jul 31st, 2007, 6:28 AM	#5
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	It's the same problem that was pointed out to you in your "Can't make the Scanner thing work" post. Consequently, the answer is the same. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Nov 1st, 2007, 9:28 PM	#6
casesensitive Programmer Join Date: Oct 2007 Posts: 41 Rep Power: 0	Re: Clearing the input box System.out.flush()

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Jul 31st, 2007, 1:09 AM	#2
357mag Hobbyist Programmer Join Date: Mar 2005 Posts: 148 Rep Power: 4	Well I think I may have found a way to fix it. If I go into the Build menu before each new run, and hit Clear and Build, then re-run the program it seems to work. But you know if you remove the println statements and change them to just print, it doesn't show up on the output until the whole program is done. In other words, when you use println("Enter a value for x: ) it will show on the output window: Enter a value for x: But if you remove the println and just code it System.out.print("Enter a value for x: ") That sentence doesn't show up at all in the output window. You can still enter in two values for the variables, but the strings and the result will not show up until the program is completely done executing.

Jul 31st, 2007, 6:06 AM	#4
357mag Hobbyist Programmer Join Date: Mar 2005 Posts: 148 Rep Power: 4	The situation happens in both Netbeans and Sun Java Studio Creator. It doesn't happen in JDeveloper or JCreator.

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Programming Forums > Application Development > Java

Clearing the input box