java:如何实现StringBuilder的replaceAll方法

Question

我用matcher实现了replaceAll()方法,用""替换所有标点符号.但它总是抛出异常:" java.lang.StringIndexOutOfBoundsException:String index out of range:6 "

private static StringBuilder filterPunctuation(StringBuilder sb){
    Pattern pattern =  Pattern.compile("(\\.)");
    Matcher matcher = pattern.matcher(sb);
    while(matcher.find()){
        sb.replace(matcher.start(), matcher.end(), "");  
// if sb.replace(matcher.start(),matcher.end()," "), it wil be right, but I want replace all punction with ""
    }
    return sb;
}

public static void main(String[] args){
    System.out.println(filterPunctuation(new StringBuilder("test.,.")));
}

Answer 1

如果要在循环内部更改StringBuilder(特别是通过删除字符的长度),则需要获取一个新的Matcher(因为旧的将继续查看原始缓冲区或两者的不一致混合).

看看Jon Skeet将如何做到这一点.