Java中的正则表达式“ ^”（脱字符）元字符
子表达式/元字符“^”与行的开头匹配。如果在正则表达式中使用此命令，则它将与输入字符串中其后的句子匹配。
例子1
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexExample {
public static void main( String args[] ) {
String regex = "^Hi how are you";
String input = "Hi how are you welcome to Nhooo";
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程序从用户接受5个字符串，并打印以数字开头的字符串。
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class StartingwithDigit {
public static void main( String args[] ) {
String regex = "^[0-9].*$";
Scanner sc = new Scanner(System.in);
System.out.println("Enter 5 input strings: ");
String input[] = new String[5]; Regular expressions - Answers
for (int i=0; i<5; i++) {
input[i] = sc.nextLine();
}
//创建一个Pattern对象
Pattern p = Pattern.compile(regex);
System.out.println("Strings starting with digits: ");
for(int i=0; i<5;i++) {
//创建一个Matcher对象
Matcher m = p.matcher(input[i]);
if(m.matches()) {
System.out.println(m.group());
}
}
}
}输出结果
Enter 5 input strings: sample string 1 sample string 2 11 sample string 3 22 sample string 4 43534 56353 636 Strings starting with digits: 11 sample string 3 22 sample string 4 43534 56353 636