End input of a string array

Question

I am trying to take input of an array of strings (each string is a question) and my code is as follows:

void read_quest()throws IOException
{
    System.out.println("enter the questions(enter null to end input operation)");
    for(int i = 0;; i++)
      {
        question[i]=in.readLine();
        if(question[i].equals("\0")==true)
        {
            n=i-1;
            break;
        }
    }
}

but the loop is never exited i am using bluej as it is for a school project(we are allowed to use only bluej) thanks in advance

Answer 1

In Java, you don't have to deal with "\0". Also, it might be hard for the user to input NUL character anyway.

The method in.readLine() returns a String that was input by the user, excluding the end-of-line character that terminates it.

• If you want to check if user presses Enter without entering any text, compare the input with the empty string "" like this:
  if ("".equals(question[i]))

• If you want to check for Ctrl+D (End of transmission character), compare with \4 as said in this post:
  if ("\4".equals(question[i])).
  Note: cannot test this in Eclipse, and the user will have to press Enter anyway after Ctrl+D

Note that if the user uses Ctrl-C, your readLine() will return null, and your program will exit not long after.

---

Side notes:

• you don't need ==true, because x.equals(y) already is a boolean.

• "literal".equals(variable) is safer than variable.equals("literal"): if your variable is null, the first version just yields false without crashing, while the second version throws NullPointerException.