Question

我试图在每个子字符串的开头插入一个字符而不是插入子字符串的位置0，该方法将字符插入整个字符串的开头。例如：

Input: esttar apple%hc orange%hc annanabar eachpar
Expected output: test apple orange banana peach
Actual output: pbtest apple orange anana each

除了StringBuilder插入方法之外，一切都按预期工作。我的代码如下。非常感谢提前。

    private String decryptText(String encrypted, String cipher){
    StringBuilder stringBuilder = new StringBuilder(); //for manipulating the substrings
    StringBuilder builder2 = new StringBuilder(); //StringBuilder object for returning and accumulating instances of decrypted
    String decryptedSS = "";

    cipher = cipher.replaceAll("-", ""); //replaces all the hyphens
    char[] cipherKey = cipher.toCharArray(); //converts the cipherKey to a character array
    char y1 = cipherKey[2];


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

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

        stringBuilder.append(subStr); //copies the substring into a String Builder object

        stringBuilder = stringBuilder.deleteCharAt(stringBuilder.length()-1); //deletes the last character
        stringBuilder = stringBuilder.deleteCharAt(stringBuilder.length()-1); //deletes the last character

        char first = stringBuilder.charAt(stringBuilder.length()-1); //copies the last character for prepending to the word if the word started with a consonant


        if(stringBuilder.charAt(stringBuilder.length()-1) == y1){ //if the last character is equal to y1
            stringBuilder.deleteCharAt(stringBuilder.length()-1); //delete it

        }
        else{ //******The problem resides in this else statement
            stringBuilder.deleteCharAt(stringBuilder.length()-1); //delete the last character
            stringBuilder.insert(0, first); //insert the copied character at the beginning of the substring
        }

        stringBuilder.append(" "); //appends a space to each word
        decryptedSS = stringBuilder.toString(); //converts the StringBuilder object to a string
    }

    builder2.append(decryptedSS); //appends the decrypted substring to the StringBuilder object to concatenate the string

    String decrypted = builder2.toString(); //converts the StringBuilder object to a string

    return decrypted; //returns the decrypted string
}

Answer 1

这一行是问题所在：

stringBuilder.insert(0, first); //insert the copied character at the beginning of the substring

此处的stringBuilder不代表当前的子字符串，而是代表您尝试构建的最终解密字符串。这就是为什么将值添加到整个字符串的开头。

您有几种选择：

您可以将循环结束时stringBuilder的结果字符串添加到builder2，然后清除stringBuilder。从你的代码编写方式来看，我想这就是你所期待的：
```
builder2.append(decryptedSS); 
stringBuilder.setLength(0); 
```
请注意，您还会删除循环外的builder2.append(decryptedSS);。
您可以在循环开始时保存stringBuilder的长度，并插入该值而不是0。
您可以在循环中完全修改subStr，并在循环结束时将完成的版本附加到stringBuilder。

StringBuilder插入方法

1 个答案: