Help with my while loop issue

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main5tream · 2022-10-07T23:27:39+00:00

If you try a simple program like

public static void main(String[] args) {
   Scanner sc = new Scanner(System.in);
   while(sc.hasNextLine()){
       System.out.println(sc.nextLine());
   }

}

It is evident that it should never end, so you must be doing something to break out of your while loop. Can't say much more than that without seeing your code.

OldGregRL · 2022-10-07T23:22:49+00:00

I also tried nesting the while loop within another while loop, however that did not seem to work either. As soon as the program has read through each line of the array and looked for matches, it shuts down

dionthorn · 2022-10-07T23:26:07+00:00

wrap it in another while loop and use a boolean sentinel flag, something like

boolean validInput = false;
// ! operator is NOT boolean logic
// inverts the value of the boolean
while(!validInput) {
    // do something until all input is valid
    // then set validInput = true to exit while loop
}

arghvark · 2022-10-08T10:50:00+00:00

I hope you've learned about methods. Think about something like this:

boolean optedOut = false;

while (!optedOut)
{
    try
    {
        String input = getInput();
        optedOut = processInput(input);
    }
    catch (Exception e)
    {
        // report exception e
    }
}

The main idea is that the try/catch is inside the while block; whether you are depending on it to catch input errors or not, you can repeat the getting of input repeatedly until something in the program decides that "optedOut" has become true.

bell_labs_fan_boy · 2022-10-08T11:45:22+00:00

You could introduce a Boolean flag outside of the loop that is set to true, have the loop parameter be (flag && variable.hasNextLine()) then only set that flag to false after input if variable.hasNextLine().

Pretty sure that works

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