java正则学习笔记

public class Demo4_Regex {

/** * Greedy 数量词     X? X，一次或一次也没有     X* X，零次或多次     X+ X，一次或多次     X{n} X，恰好 n 次     X{n,} X，至少 n 次     X{n,m} X，至少 n 次，但是不超过 m 次  */public static void main(String[] args) {    //demo1();    //demo2();    //demo3();    //demo4();    //demo5();    String regex = "[abc]{5,15}";    System.out.println("abcba".matches(regex));    System.out.println("abcbaabcabbabab".matches(regex));    System.out.println("abcb".matches(regex));    System.out.println("abcbaabaabcbaaba".matches(regex));}public static void demo5() {    String regex = "[abc]{5,}";    System.out.println("abcba".matches(regex));    System.out.println("abcbaabcabbabab".matches(regex));    System.out.println("abcb".matches(regex));    System.out.println("abcbaaba".matches(regex));}public static void demo4() {    String regex = "[abc]{5}";    System.out.println("abcba".matches(regex));    System.out.println("abcbaabcabbabab".matches(regex));    System.out.println("abcb".matches(regex));    System.out.println("abcbaaba".matches(regex));}public static void demo3() {    String regex = "[abc]+";    System.out.println("".matches(regex));    System.out.println("a".matches(regex));    System.out.println("aaaaabbbbccccc".matches(regex));}public static void demo2() {    String regex = "[abc]*";    System.out.println("".matches(regex));    System.out.println("abc".matches(regex));    System.out.println("a".matches(regex));}public static void demo1() {    String regex = "[abc]?";    System.out.println("a".matches(regex));    System.out.println("b".matches(regex));    System.out.println("c".matches(regex));    System.out.println("d".matches(regex));    System.out.println("".matches(regex));}

}