使用循环创建变量

Question

我正在编写一个程序，该程序应该用另一个字母替换单个字母的所有实例。虽然我对代码有一些限制，但我只能使用字符串方法 .length、.substring、.indexOf 和 .equals。我可以使用 + 而不是 .concat 来连接事物。

我现在的问题是，当我将结果打印到程序中时，答案必须包含在变量中。在我意识到这一点之前，我以前使用过这段代码：

    if (userCommand.equalsIgnoreCase("replace all")) {
        System.out.println("Enter the character to replace");
        String replace = keyboard.nextLine();
        System.out.println("Enter the new character");
        String replaceWith = keyboard.nextLine();

        int count = 0;

        System.out.print("The new string is: ");
        while (lastCharacter >= 0) {
            char nextCharacter = userString.charAt(count);
            count++;
            String nextCharacterString = nextCharacter + "";
            if (nextCharacterString.equals(replace)) {
                nextCharacterString += replaceWith;
            }
            System.out.print(nextCharacterString);

            lastCharacter--;
        }
        System.out.println("");
    }

如您所见，这会将每个字符一个一个地打印到控制台，而不是作为以后可以操作的变量。我现在使用的代码（它离工作还很远）是：

    if (userCommand.equalsIgnoreCase("replace all")) {
        System.out.println("Enter the character to replace");
        String replaceString = keyboard.nextLine();
        char replace = replaceString.charAt(0);
        System.out.println("Enter the new character");
        String replaceWithString = keyboard.nextLine();
        char replaceWith = replaceWithString.charAt(0);
        String allLetters = "";
        int count = 0;
        int indexOfReplacement = 0;

        for (int i = 0; i < length; i++) {
            char nextCharacter = userString.charAt(count);
            count++;

            if (replace == nextCharacter) {
                indexOfReplacement = count;
                nextCharacter = replaceWith;
            }
        }
        String sub1 = userString.substring(0, indexOfReplacement);
        System.out.println(sub1);
    }

非常感谢任何帮助。

Answer 1

这是我写的一个小sn-p。我对变量的内容做了一些假设以使其能够运行，但它可以工作，用replaceWith 替换所有replace 实例：

String your_string = ""; // Variable to copy the new string into
String userString = "this_string"; // String to do replacement on
int lastCharacter = userString.length() - 1; // Length of inputted string
String replace = "g"; // Thing to replace
String replaceWith = "d"; // Thing to replace with
int count = 0; // Index of character in string
while(lastCharacter >= 0) {
    char nextCharacter = userString.charAt(count);
    String nextCharacterString = nextCharacter + "";
    if (nextCharacterString.equals(replace)) {
        nextCharacterString = replaceWith; // I changed += to = because we want to replace, not add
    }
    System.out.print(nextCharacterString);
    your_string = your_string + nextCharacterString; // This is where we add the correct character to the string
    lastCharacter--;
    count++;
}

Answer 2

您可以使用arraylist

ArrayList<String> list=new ArrayList<String>();
while(lastCharacter >= 0)
              {
                  char nextCharacter = userString.charAt(count);
                  count ++;
                  String nextCharacterString = nextCharacter + "";
                  if (nextCharacterString.equals(replace))
                  {
                      nextCharacterString += replaceWith;  
                  }
                  System.out.print(nextCharacterString);
                  list.add(nextCharacterString);
                  lastCharacter --;
              }

这样你以后可以操作它