多个JOptionPane输入发送到一个String输出

Question

First time poster here. You guys seem to always have answers when I'm stuck and end up googling the question. I'm usually directed here for answers.

I'm in an intro to java class in college, and so far so good. The snag I hit with my homework tonight made me decide to sign up and ask you all (because I'm too impatient and don't want to wait for my professor to email me back).

In the first part of my homework, I have to ask 4 questions to the user (using display boxes), but am instructed to have one String in the method. I assume this one String is going to prompt the user 4 different times. Got that to work. When I show the user their choices for each question, I get a display box with every answer with no spaces or line breaks.

My question is, is there a way to force line breaks after each question, even though every question is going to one String?

Here's my code for you to check out. Before you say anything about me not using JOptionPane.YES_NO_CANCEL_OPTION, for my yes/no questions, we haven't covered them in class, so my professor is not looking for us to be using that just yet. I look forward to hearing what advice you have to offer.

package week4_project;

import javax.swing.*;

public class Week4_Methods_Assignment 
{
    //Constants of Dialog Box types
        final public static int ERROR = 0;
        final public static int INFORMATION = 1;
        final public static int WARNING = 2;
        final public static int QUESTION = 3;
        final public static int PLAIN = -1;

    //Main method
    public static void main(String[] args) 
    {
        final String ASKUSER = getUserInput();
        String message = "";

        message = ASKUSER;

        JOptionPane.showMessageDialog(null, message, "", INFORMATION);

        System.exit(0);     
    }//end of main

    /*This method will ask the user questions about 
      how they drink coffee*/ 
    private static String getUserInput()
    {

        String question = "";

        question += JOptionPane.showInputDialog(null,
                "Regular or decaf", "Type of coffee", QUESTION);
        question = question.trim();

        question += JOptionPane.showInputDialog(null, "Yes or No", 
                "Do you take cream?", QUESTION);
        question = question.trim();

        question += JOptionPane.showInputDialog(null, "Yes or No", 
                "Do you take sugar?", QUESTION);
        question = question.trim();

        System.out.println(question);

        return question;        
    }

}//end of class

Answer 1

You can put System.lineSeparator in your string by concatenating. This returns the proper line separator for your operating system.

question += JOptionPane.showInputDialog(null, "Regular or decaf", "Type of coffee", QUESTION);
question = question.trim() + System.lineSeparator();

---

Note that if you are building strings you need to start using StringBuilder to do that, rather than concatenating strings with += .

If you concatenate strings the way you are doing it now, you are creating a new String object each time you call question += "..."; . This will trash the heap and lead to fragmentation, it will also consume more memory and lead to more garbage collections to free memory.

If you instead use StringBuilder with a suitable capacity , you will not trash the heap. Instead, this class prepares a buffer of suitable length that gets filled as you append strings to it.

When your string is finally built, call StringBuilder.toString to get the string you want.