help with detecting certain characters

**goochasauras** · September 27th, 2012, 02:00 PM

So i have a do while loop and i have user input coming in to detect which character the user entered...i want it to loop until the user enters a valid character...q or Q quits the program, whereas r,R,c,C are all valid characters. If a different character, for example 'L' were entered, it should loop back until a proper character is entered...I'm a beginner and i simply don't know the commands or logic behind this to be able to do this and any help would be greatly appreciated.

Here is what I have:

 	do {
			input = JOptionPane.showInputDialog("Please enter shape of pizza, R or C (Q to quit)");
			if(input == null || input.toUpperCase().equals("Q")) {
			    return;
			}
			} while (input.toUpperCase().equals("C") || !input.toUpperCase().equals("R"));
 
			shape = input;

**pbrockway2** · September 27th, 2012, 02:12 PM

The general idea of your code is OK.

The while condition should not have anything to do with "Q", however. Also a "bad" input like "L" is not "C" AND it is not "R" etc.

---

if(input == null || input.equals("q") || input.toUpperCase().equals("Q")) {

This is more neatly written as

if(input == null || input.toUpperCase().equals("Q")) {

The toUpperCase() takes care of "q" and "Q" wth one check. A similar idea can be used in your while condition.

**goochasauras** · September 27th, 2012, 02:25 PM

I edited to code so it is a little cleaner like you mentioned...but how do i get, in the while part of the statement, the program to loop until c or r are entered but still quitting when q is entered it's a problem only in the while statement i believe

**pbrockway2** · September 27th, 2012, 03:30 PM

There are two things going on here. First the return when q is entered is taken care of by the if statement. The second is to keep looping while input is not c/r, and that's what the while condition is supposed to ensure.

Did you understand what I said about AND rather than OR?

If your code is not doing what you expect, post the updated version and describe what it is doing as you test it.

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