默認情況下,正則表達式 ^ 和 $ 忽略行結束符,僅分別與整個輸入序列的開頭和結尾匹配。如果激活 MULTILINE 模式,則 ^ 在輸入的開頭和行結束符之後(輸入的結尾)才發生匹配。處於 MULTILINE 模式中時,$ 僅在行結束符之前或輸入序列的結尾處匹配。
import java.util.regex.Pattern; /** * Created by Frank * 使用正則表達式在文本中查找換行符 */ public class NLMatch { public static void main(String[] args) { String input = "I dream of engines\nmore engines, all day long"; System.out.println("INPUT:" + input); System.out.println(); String[] patt = {"engines.more engines", "ines\nmore", "engines$"}; for (int i = 0; i < patt.length; i++) { System.out.println("PATTERN:" + patt[i]); boolean found; Pattern p1l = Pattern.compile(patt[i]); found = p1l.matcher(input).find(); System.out.println("DEFAULT match " + found); // .代表任何符號(DOT ALL), Pattern pml = Pattern.compile(patt[i], Pattern.DOTALL | Pattern.MULTILINE); found = pml.matcher(input).find(); System.out.println("Multiline match " + found); System.out.println(); } } }