Java 点不匹配 'any character'

Question

点应该匹配任何字符。那么为什么这个正则表达式不起作用？

String url = "http://wikipedia.org";
System.out.println(url.replace("htt.://", ""));

输出:http://wikipedia.org

Answer 1

String.replace()编译一个文字正则表达式。你应该使用 String.replaceAll()或 String.replaceFirst() :

String url = "http://wikipedia.org";
System.out.println(url.replaceFirst("htt.://", ""));

这里是来自Java源代码，方法.replace():

/**
 * Replaces each substring of this string that matches the literal target
 * sequence with the specified literal replacement sequence. The
 * replacement proceeds from the beginning of the string to the end, for
 * example, replacing "aa" with "b" in the string "aaa" will result in
 * "ba" rather than "ab".
 *
 * @param  target The sequence of char values to be replaced
 * @param  replacement The replacement sequence of char values
 * @return  The resulting string
 * @throws NullPointerException if <code>target</code> or
 *         <code>replacement</code> is <code>null</code>.
 * @since 1.5
 */
public String replace(CharSequence target, CharSequence replacement) {
    return Pattern.compile(target.toString(), Pattern.LITERAL).matcher(
            this).replaceAll(Matcher.quoteReplacement(replacement.toString()));
}