家庭作业帮助：为什么变量不返回

Question

我无法弄清楚

我的

变量没有返回打印在输出消息中，我不知道我哪里出错了，我的老师告诉我逐行检查代码并检查逻辑和语法错误。任何帮助将不胜感激。

package selfhelpstore;  
import javax.swing.JOptionPane;  
public class SelfHelpStore {  
    private static String getStringInput(String prompt) {  
        String input = JOptionPane.showInputDialog(prompt);  
        String nullFlag = "n";
        int i = 1;
        while (i<=2)
        if (input == null) {
            System.exit(0);
        }else if (input.isEmpty()) {
            i++;
            nullFlag = "y";
            prompt = JOptionPane.showInputDialog("Re-enter: ");
        } else {
            i=4;
            nullFlag = "n";
        }
        if (!input.isEmpty()) {
            nullFlag = "n";
        }
        if (nullFlag.equals("y")) {
            JOptionPane.showMessageDialog(null, "Null or blank - exiting...");
            System.exit(0);
        }
        return prompt;
    } 
    public static void main(String[] args) {
        String openingMsg, nameInputMsg, customerName, nameOutputMsg, 
               returnInputMsg, customerReturn, returnOutputMsg, 
               greetingOutputMsg, outputMsg,coverInputMsg, coverMsg ;
        openingMsg = "*** Welcome to Self Help Book Store Online Ordering System ***n"
                   + "                     It's a great day to read a book!";
        JOptionPane.showMessageDialog(null, openingMsg);
        nameInputMsg   = getStringInput("Please enter your name: ");   
                customerName   = nameInputMsg;
                returnInputMsg = getStringInput("Are you a returning customer (yes or no)?     ");
        customerReturn = returnInputMsg;
                coverInputMsg = getStringInput("would you like this book in hard cover or     paper back?");
                coverMsg = coverInputMsg;
        nameOutputMsg     = "Welcome " + customerName + ".nn";
        returnOutputMsg   = "Your return customer status is " + customerReturn + ".n";
        greetingOutputMsg = "Thank you for visiting our Self Help Book Store!" + "n"
                        + "Your " + coverMsg + " should be mailed in less than two     business days.n";
        outputMsg = nameOutputMsg + returnOutputMsg + greetingOutputMsg;
        JOptionPane.showMessageDialog(null, outputMsg);
        System.exit(0);
    }
}

Answer 1

当你希望它返回输入时，你的getStringInput方法正在返回变量提示。

private static String getStringInput(String prompt) {
    String input = JOptionPane.showInputDialog(prompt);
    String nullFlag = "n";
    int i = 1;
    while(i <= 2)
        if(input == null)
        {
            System.exit(0);
        } else if(input.isEmpty())
        {
            i++;
            nullFlag = "y";
            prompt = JOptionPane.showInputDialog("Re-enter: ");
        } else {
            i = 4;
            nullFlag = "n";
        }
    if(!input.isEmpty()) {
        nullFlag = "n";
    }
    if(nullFlag.equals("y")) {
        JOptionPane.showMessageDialog(null, "Null or blank - exiting...");
        System.exit(0);
    }
    return input;  // Change this line
}