Do While Questions

Question

Ok, I'm taking a Comp. Prog. class at my high school and the teacher that "teaches" the class knows practically nothing about programming. I joined the Java UIL team and am teaching the class with curriculum from some college website. Anyways, I started writing a Body Mass Index Calculator yesterday, and have had success but my problem is that I want to have a println prompt to run the program again after the calculations have been completed. Now, I have learned the Do While loop for this occasion, but my problem is with the scanner. I want to receive input as a string but when I do

String a = sc.nextLine();

outside of the do, it says that y or yes, cannot be resolved to a variable. A friend suggested switch cases, what do you think? I use Eclipse BTW.

String a = sc.nextLine();
do{
    wow(); //My method name
}while(a == y); //Error is here

your test should be `a.equals("y")` don't use `==` with strings see http://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java — vandale, Nov 19 '13 at 17:53
You might need `while("Y".equalsIgnoreCase(a) || "YES".equalsIgnoreCase(a))` — Smit, Nov 19 '13 at 17:55

score 0 · Answer 1 · answered Nov 19 '13 at 17:54

0

To compare objects in java use .equals() method instead of "==" operator

Use while(a.equals("y")); instead of while(a == y);

answered Nov 19 '13 at 17:54

Prabhakaran Ramaswamy

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score 0 · Answer 2 · answered Nov 19 '13 at 17:55

while(a == y);

This will never work for two reasons:

== compares references, not the contents of the object. So here it is only checking that a and y point to the same object, not that they contain the same thing.
You have not declared y anywhere. I'm assuming that you want to compare a against the literal string "y", in which case you should be using a.equals("y").

Your loop can be structured like this:

String input;
do {
    wow();
    input = scanner.nextLine();
} while(input.equalsIgnoreCase("y"));  //using equalsIgnoreCase because user
                                       //can input "y" or "Y".

Do While Questions

2 Answers2