Question about JOptionPane

[eviljeff]

I am a programming student, and I unfortunately missed class today. Today my professor probably discussed what JOptionPane is, which I missed.

I'm currently working on a problem where I must declare an object keyboard of type Scanner, then declare and initialize a variable 'num', and declare and initialize a String variable to store user input. My next task is to prompt the user for input from the keyboard, and then store the user input into the String variable. So far, this is what I've got:

Scanner keyboard = new Scanner(System.in);
int num = 0;
String inputString;
inputString = JOptionPane.showInputDialog("Enter an integer: ");

Now, I'm not sure what JOptionPane actually does, because I've missed today's lecture. But the above code is from an example he left on the Blackboard site. So I now have two questions: (1) instead of the last line of the above code, could I just use the following? :

System.out.println("Enter an integer: ");
inputString = keyboard.nextString();

Question (2) Considering I use the method described in my question (1), does the following make sense to use to complete the program? :

//convert input to integer
num = Integer.parseInt(inputString);

//display the results
JOptionPane.showMessageDialog(null, "The value of the integer is: " + num);

//end program
System.exit(0);
}

Any help would be greatly appreciated!

[pbrockway2]

Yes and yes. I think - but you'll be sure when you try them.

JOptionPane is discussed on the How to Make Dialogs page of Oracle's Tutorial.

[eviljeff]

Thank you very much! :) I am having some trouble compiling the .java file, however. But I think it is unrelated to the code and more of an issue with the compiler. I'm not sure if I have everything I need to compile and run java code. I'm using Linux -- Xubuntu 11.10. Would you by any chance know what packages I would need to be able to work with java?

[pbrockway2]

I don't know offhand. But ?Ubuntu is generally pretty good about installing packages.

My guess would be

sudo apt-get install openjdk-7-jre

If you have an existing Java runtime or compiler you may have to check after an install that "which java" and "which javac" report the correct (and same!) versions.