替换String中的单个字符

Question

问题是需要替换给定字符串中的单个字符，同时保留字符串中的其他字符。

代码是：

    if(command.equalsIgnoreCase("replace single"))
    {
        System.out.println("Enter the character to replace");
        String char2replace = keyboard.nextLine();
        System.out.println("Enter the new character");
        String secondChar = keyboard.nextLine();    
        System.out.println("Which " + char2replace + " would you like to replace?");
        int num2replace = keyboard.nextInt();

            for(int i=0; i< bLength; i++)
            {   

                if(baseString.charAt(i)== char2replace.charAt(0))
                {
                    baseString = baseString.substring(0, i) +
                            secondChar + baseString.substring(i + 1);

                }

Answer 1

你几乎做到了，只需在循环中添加一个计数器：

int num2replace = keyboard.nextInt();
int count = 0;
for (int i = 0; i < bLength; i++) {
    if (baseString.charAt(i) == char2replace.charAt(0)) {
        count++;
        if (count == num2replace){
            baseString = baseString.substring(0, i) +
                    secondChar + baseString.substring(i + 1);
            break;
        }
    }
    if (char2replace.length() > 1) {//you need move this out of loop
        System.out.println("Error you can only enter one character");
    }


}
System.out.println(baseString);

Answer 2

您可以使用command.replaceAll("and", "a")例如

Answer 3

您可以使用StringBuilder替换某个索引处的单个字符，如下所示：

<meta http-equiv="X-UA-Compatible" content="IE=edge">

阅读有关StringBuilder的setCharAt（）方法here的更多信息。