Java中的正则表达式re {n，m}元字符
子表达式/元字符“re{n，m}”与前面的表达式的至少n个和最多m个匹配。
例子1
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexExample {
public static void main( String args[] ) {
String regex = "xyy{2,4}";
String input = "xxyyzxxyyyyxyyzxxyyzz";
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(input);
int count = 0;
while(m.find()) {
count++;
}
System.out.println("Number of matches: "+count);
}
}输出结果
Number of matches: 1
例子2
以下Java程序从用户读取名称值，并且仅允许1到20个字符。
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexExample {
public static void main(String args[] ) {
//Regular expression to match characters at least 1 almost 20
String regex = "[a-zA-Z]{1,20}";
Scanner sc = new Scanner(System.in);
System.out.println("Enter students name:");
String name = sc.nextLine();
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(name);
if(m.matches()) {
System.out.println("Name is appropriate");
} else {
System.out.println("Name is inappropriate");
}
}
}输出1
Enter students name: Mouktika Name is appropriate
输出2
Enter students name: ka 34 Name is inappropriate
输出3
Enter students name: Sri Veera Venkata Satya Sai Suresh Santosh Samrat Name is in inappropriate