Question

该程序旨在查找用户输入是否为回文结构。但是在isPalindrome方法中，我一直得到规定的错误。当我修复它时，我得到24个错误，说它找不到多个其他变量。请帮忙。

以下是代码：

import java.util.Scanner;

public class Project4
{
    public static void main (String [] args) {

        String line = getInputLine();
        while (!isEmptyLine (line)) {
            if (isPalindrome (line))
                System.out.println ("\"" + line +
                    "\" is a palindrome and a " + getPalType (line));
            else
                System.out.println ("\"" + line +
                    "\" is not a palindrome");
                line = getInputLine();

            }
            System.out.println ("End of prgram");
        }

    public static String getInputLine () //Ask user for input and then returns the line
    {
        Scanner scan = new Scanner(System.in);
        System.out.print("Enter your possible Palindrome: ");
        String getInputLine = scan.nextLine();
        return getInputLine;
    }


    public static boolean isEmptyLine (String str) // Return TRUE if the paramater is empty or False otherwise
    {
        if (line != null)
        {
            isEmptyLine = true;
        }
        else
        {
            isEmptyLine = false;
        }
    }

    public static boolean isPalindrome (String str)// Return TRUE if the str is a palindrome or FALSE otherwise
    {
        int left = 0;
        int right = line.length() - 1;
        boolean okay = true;

        while (okay && left < right){

            char ch1 = line.charAt(left);

            if (!(Character.isDigit(ch1) || Character.isLetter(ch1))){

                left ++;

            else{
                ch2 = line.charAt(right);
            }

                if (!(Character.isDigit(ch2) || Character.isLetter(ch2))){
                    right --;

                else{
                    ch1 = Character.toUpperCase(ch1);
                    ch2 = Character.toUpperCase(ch2);
                }
                if (ch1 == ch2){
                    left ++;
                    right --;

                else{
                    okay = false;
                }
                }
            }
        }
    }
    return okay;
}

public static String getPalType (String str)//Determine the type of the palindrome and return either word/phrase/number.
{
    int num = 0;
    int let = 0;
    int length = line.length();

    for (int i = 0; i <= length; i++)
    {
        if (Character.isDigit(line.charAt(i)))
            num++;
        else if (Character.isLetter(line.charAt(i)))
            let++;
    }

    if (num > 0 && let == 0)
    {
        getPalType = number;
        return getPalType;
    }
    else if (let > 0 && num == 0)
    {
        getPalType = word;
        return getPalType;
    }
    else
        getPalType = phrase;
        return getPalType;

    }
}

Answer 1

错过了

的最佳起始位置

  if (isPalindrome (line))

如果您有一个或另一个，则不能使用结束一行样式。只需添加开始括号即可。

需要这样：

while (!isEmptyLine (line)) {
    if (isPalindrome (line)){
        System.out.println ("\"" + line +
            "\" is a palindrome and a " + getPalType (line));
    }else{
        System.out.println ("\"" + line +
            "\" is not a palindrome");
        line = getInputLine();

    } //since you have two lines not one in the else.
    }
    System.out.println ("End of prgram");

否则没有If错误（回文计划）

1 个答案: