解释Java正则表达式中的元字符“ \ B”。
子表达式/元字符“\B”与非单词边界匹配。
例子1
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexExample {
public static void main( String args[] ) {
String regex = "\\Bcause";
Scanner sc = new Scanner(System.in);
System.out.println("Enter a string: ");
String input = sc.nextLine();
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
Enter a string: A sentence doesn't end with because because, because is a conjunction Number of matches: 3
例子2
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main( String args[] ) {
System.out.println("Enter input string: ");
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
String regex = "\\B";
//Compiling the regular expression
Pattern pattern = Pattern.compile(regex);
//Retrieving the matcher object
Matcher matcher = pattern.matcher(input);
int count =0;
System.out.println("Non-word boundaries: ");
while(matcher.find()) {
count ++;
}
System.out.println(count);
}
}输出结果
Enter input string: Hello how are you welcome to Nhooo Non-word boundaries: 30