Question

我正在尝试使用deleteCharAt（0）方法删除位置0处的字符，并将该字符（已经复制）附加到末尾。该字符将追加到末尾，但deleteCharAt（0）方法未执行。我不知道为什么它不起作用。

    Input:  Test test test 
    Expected output:  esttqw esttqw esttqw 
    Actual output:  ttqw testtqw testtqw

以下是我的代码。非常感谢。

    pT = pT.toLowerCase(); //converts the string to lower case

    String[] strArr = pT.split(" "); //splits the string into an array


    for(String subStr : strArr){ //for each substring in the string array

        char first = subStr.charAt(0);
        stringBuilder.append(subStr); //converts the string to a stringbuilder object

        if((first=='a') || (first == 'e') || (first == 'i') || (first == 'o') || (first == 'u')){ //starts with a vowel
            stringBuilder.append((char)charRand1); //appends y1 to the end of the string
            stringBuilder.append((char)alphaRand3); //appends x3 to the end of the string
            stringBuilder.append((char)alphaRand4); //appends x4 to the end of the string
            stringBuilder.append(" ");
            encryptedSS = stringBuilder.toString(); //converts stringbuilder back to string
        }
        else{ //starts with a consonant
            stringBuilder.deleteCharAt(0); //deletes the first character
            stringBuilder.append(first); //appends the first character to the end of the word
            stringBuilder.append((char)alphaRand1); //append x1 to the end of the word
            stringBuilder.append((char)alphaRand2); //append x2 to the end of the word*/
            stringBuilder.append(" ");

            encryptedSS = stringBuilder.toString(); //converts string builder back to an array
        }

    }

Answer 1

您的代码段没有显示您初始化stringBuilder的位置，但似乎您在循环之外执行了一次。因此，调用deleteCharAt(0)只会删除整个结果的第一个字符，而不是您当前正在处理的字符串。为了避免这种情况，您可以为每个处理的字符串创建一个临时的StringBuilder：

for(String subStr : strArr) {
    // New StringBuilder per String
    StringBuilder stringBuilder = new StringBuilder(subStr);

    char first = subStr.charAt(0);

    if ((first=='a') || (first == 'e') || (first == 'i') || (first == 'o') || (first == 'u')){ //starts with a vowel
        stringBuilder.append((char)charRand1); //appends y1 to the end of the string
        stringBuilder.append((char)alphaRand3); //appends x3 to the end of the string
        stringBuilder.append((char)alphaRand4); //appends x4 to the end of the string
        stringBuilder.append(" ");
        encryptedSS = stringBuilder.toString(); //converts stringbuilder back to string
    }
    else{ //starts with a consonant
        stringBuilder.deleteCharAt(0); //deletes the first character
        stringBuilder.append(first); //appends the first character to the end of the word
        stringBuilder.append((char)alphaRand1); //append x1 to the end of the word
        stringBuilder.append((char)alphaRand2); //append x2 to the end of the word*/
        stringBuilder.append(" ");

        encryptedSS = stringBuilder.toString(); //converts string builder back to an array
    }

Answer 2

我需要添加另一个StringBuilder对象来组装所有子字符串。

    pT = pT.toLowerCase(); //converts the string to lower case

    String[] strArr = pT.split(" "); //splits the string into an array


    for(String subStr : strArr){ //for each substring in the string array
        char first = subStr.charAt(0);

        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append(subStr);

        if((first=='a') || (first == 'e') || (first == 'i') || (first == 'o') || (first == 'u')){ //starts with a vowel
            stringBuilder.append((char)charRand1); //appends y1 to the end of the string
            stringBuilder.append((char)alphaRand3); //appends x3 to the end of the string
            stringBuilder.append((char)alphaRand4); //appends x4 to the end of the string
            stringBuilder.append(" ");
            encryptedSS = stringBuilder.toString(); //converts stringbuilder back to string
        }
        else{ //starts with a consonant
            stringBuilder.deleteCharAt(0); //deletes the first character
            stringBuilder.append(first); //appends the first character to the end of the word
            stringBuilder.append((char)alphaRand1); //append x1 to the end of the word
            stringBuilder.append((char)alphaRand2); //append x2 to the end of the word*/
            stringBuilder.append(" ");

            encryptedSS = stringBuilder.toString(); //converts string builder back to an array
        }

        builder2.append(encryptedSS); //appends the encrypted substring to the stringbuilder
    }

StringBuilder方法deleteCharAt不删除该字符

2 个答案: