Morse to English 程序中 Java 的输出不正确

Question

这是我的摩尔斯电码到英语和副 Versa 的分配标准：

1. 在摩尔斯电码中，|代表空格。
2. 在摩尔斯电码中，空格代表新的字母或数字。

我的代码编译正确，但输出（运行后）不正确。

// Import Scanner.
import java.util.Scanner

public class Project1_szhu1249322
{
public static void main(String[] args)
{
    Scanner input = new Scanner (System.in);
    System.out.println("Would you like to translate 'Morse Code' to English, or 'English' to Morse code? (Enter 'Morse Code' or 'English'.)");
    String unit1 = input.nextLine();
    System.out.println("Enter a string of " + unit1 + " characters (for English, numbers and letters, only): ");
    String amountUnit1 = input.nextLine();
    if (unit1 == "Morse Code")
        toEnglish(amountUnit1);
    else if (unit1 == "English")
        toMorseCode(amountUnit1);
    else
        System.out.println("Invalid data. Enter 'Morse Code' or 'English' without the single quotes.");
}

public static void toMorseCode(String english)
{
    // Declare variables, arrays, and strings.
    int i = 0;
    int l = english.length();
    int i2 = 2 * i;
    String[] lowerAlphabet = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","1", "2", "3", "4", "5", "6", "7", "8", "9", "0"};
    String[] upperAlphabet = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","1", "2", "3", "4", "5", "6", "7", "8", "9", "0"};
    String[] morseCode = {".-", "-...", "-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--..",".----","..---","...--","....-",".....","-....","--...","---..","----.","-----"};
    morseCode[i] = lowerAlphabet[i];
    StringBuilder morseBuilder = new StringBuilder();

    // for loops and if statements for result.
    for (i = 0; i < l; i++)
    {
        i2 = 2 * i;
        if (english.charAt(i) != ' ')
            morseBuilder.append(morseCode[i2]);
        else
            morseBuilder.append('|');

        if (morseBuilder.charAt(i - 1) != ' ' && morseBuilder.charAt(i + 1) != 0)
            morseBuilder.append(' ');
    }

    morseCode[i] = upperAlphabet[i];
    // for loops and if statements for result.
    for (i = 0; i < l; i++)
    {
        i2 = 2 * i;
        if (english.charAt(i) != ' ')
            morseBuilder.append(morseCode[i2]);
        else
            morseBuilder.append('|');

        if (morseBuilder.charAt(i - 1) != ' ' && morseBuilder.charAt(i + 1) != 0)
            morseBuilder.append(' ');
    }

    // Display results.
    System.out.println("The corresponding Morse code is " + morseBuilder + ".");
}

public static void toEnglish(String morse)
{
    // Declare variables, arrays, and strings.
    int i = 0;
    int l = morse.length();
    int i2 = i / 2;
    String[] lowerAlphabet = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","1", "2", "3", "4", "5", "6", "7", "8", "9", "0"};
    String[] upperAlphabet = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","1", "2", "3", "4", "5", "6", "7", "8", "9", "0"};
    String[] morseCode = {".-", "-...","-.-.","-..",".","..-.","--.","....","..",".---","-.-",".-..","--","-.","---",".--.","--.-",".-.","...","-","..-","...-",".--","-..-","-.--","--..",".----","..---","...--","....-",".....","-....","--...","---..","----.","-----"};

    morseCode[i] = upperAlphabet[i];
    String english;

    StringBuilder englishBuilder = new StringBuilder();

    // for loops and if statements for result.
    for (i = 0; i < l; i++)
    {
        i2 = i / 2;
        if (morse.charAt(i) == '|')
        {
            englishBuilder.append(' ');
        }
        else
            englishBuilder.append(morseCode[i2]);
    }

    morseCode[i] = lowerAlphabet[i];
    // for loops and if statements for result.
    for (i = 0; i < l; i++)
    {
        i2 = i / 2;
        if (morse.charAt(i) == '|')
        {
            englishBuilder.append(' ');
        }
        else
            englishBuilder.append(morseCode[i2]);
    }

    // Display results.
    System.out.println("The corresponding English is " + englishBuilder + ".");
}
}

我的输出是这样的：

Would you like to translate 'Morse Code' to English, or 'English' to Morse code? (Enter 'Morse Code' or 'English'.)
English
Enter a string of English characters (for English, numbers and letters, only): 
to be
Invalid data. Enter 'Morse Code' or 'English' without the single quotes.

它不会转到正确的 if-else 分支。它没有转到unit1 == "English"，而是转到最后一个else for Invalid Data。

另外，对于toEnglish方法中的for循环，我应该如何设置i2？我需要 i / 2，但前提是第一个字符不是空格。

Answer 1

当您创建 translated 字符串时，您应该使用以下内容而不是 charAt() =，后者不允许赋值：

StringBuilder bob = new StringBuilder();

for (...){
    if (...){
        bob.append(character);
    }
}
String english = bob.toString();

此外，i2 将始终等于 0。

这里还有许多其他小错误。继续调试，您最终将解决所有问题。

Answer 2

morse.charAt(i) 是一个函数，不能站在赋值的左边。如果需要替换字符，先把字符串转成char数组：

 char[] english = morse.toCharArray();
 english[i] = '|';

如果需要，您可以在完成后转换回字符串 (new String(myArray))。阅读String。

这就是错误的原因。正如@Milk 所建议的，当您逐个字符地构建答案时，最合理的方法是通过StringBuilder。与数组不同，StringBuilder 知道如何增长，创建时无需指定大小。

Answer 3

还有一个错误

Project1_szhu1249322.java:67：错误：不兼容的类型：char 无法转换为 String 莫尔斯电码[i2] = english.charAt(i);

morseCode[i2] 返回String，而english.charAt(i) 返回原始类型char。更改为 morseCode[i2] = String.valueOf(english.charAt(i)); 将它们都带入 String