java正则表达式的简单运用

public static void main(String[] args) {
 String pattern="a\\d{2}f";//模型：以a开始，接2位数字，以f结尾
 String s="a22";
 boolean b=s.matches(pattern);
 System.out.println(s+"匹配"+pattern+"吗："+b);
 s="a22f";
 b=s.matches(pattern);
 System.out.println(s+"匹配"+pattern+"吗："+b);
}

public static void main(String[] args) {
 String s="你你   好 吗吗吗 ";
 System.out.println("替换前："+s);
 String pattern="\\s+";
 s=s.replaceAll(pattern, "");
 System.out.println("替换后："+s);
}

public static void main(String[] args) {
 String s="你你好吗吗吗";
 System.out.println("替换前："+s);
 String pattern="(.)\\1+";
 s=s.replaceAll(pattern, "$1");
 System.out.println("替换后："+s);
}