这些特殊字符在Java中意味着什么？ [英] What do these special characters mean in Java?

问题描述

我正在查看一些jdk代码。我找到了这些角色。有人可以向我解释这些是什么意思。

I was looking at some of the jdk code. I found these characters. Could someone explain to me what do these mean.

public static String quote(String s) {
    int slashEIndex = s.indexOf("\\E");        // What does this mean. Is this a special char in java. if so what does this do.
    if (slashEIndex == -1)
        return "\\Q" + s + "\\E";          

    StringBuilder sb = new StringBuilder(s.length() * 2);
    sb.append("\\Q");
    slashEIndex = 0;
    int current = 0;
    while ((slashEIndex = s.indexOf("\\E", current)) != -1) {
        sb.append(s.substring(current, slashEIndex));
        current = slashEIndex + 2;
        sb.append("\\E\\\\E\\Q");
    }
    sb.append(s.substring(current, s.length()));
    sb.append("\\E");
    return sb.toString();
}

从上面的代码示例中，我能够弄清楚发生了什么method查找\的出现次数并将它们转换为\E和\Q。有人可以解释为什么会这样。

From the above code example I was able to figure out what's happening as in the method finds the occurrences of \ and converts them to \E and \Q. Could someone explain why that's the case.

有关此方法的更多上下文，我正在研究jdk 1.6中的Pattern.quote（）方法

For more context on this method, I was looking into the Pattern.quote() method from jdk 1.6

推荐答案

\ Q 和 \ E 正是 Pattern.quote（）确实，即返回指定字符串的文字模式字符串。

有关详细信息，请参阅此链接：

http://docs.oracle.com/javase/1.5.0/docs/api/java/util/regex/Pattern。 html

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