1, Greedy quantifiers
-
? X X, once or not even once "[abc]?";
-
X * X, zero or more times "[abc] *";
-
X + X, one or more "[abc] +";
-
X {n} X, exactly n times "[abc] {5}";
-
X {n,} X, at least n "[abc] {5,}";
-
X {n, m} X, at least n times, but not more than m times "[abc] {5,15}"; comprising header. It does not include the tail
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));
}
}