如何使用Java RegEx匹配特定字符串/行的开头
元字符“^”匹配特定字符串的开头，即，它匹配字符串的第一个字符。例如，
表达式“^\\d”与以数字开头的字符串/行匹配。
表达式“^[az]”匹配以小写字母开头的字符串/行。
例子1
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main(String args[]) {
//从用户读取字符串
System.out.println("Enter a String");
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
String regex = "^[^a-zA-Z0-9//s].*";
//编译正则表达式
Pattern pattern = Pattern.compile(regex);
//检索匹配器对象
Matcher matcher = pattern.matcher(input);
if(matcher.matches()) {
System.out.println("Match occurred");
} else {
System.out.println("Match not occurred");
}
}
}输出结果
Enter a String #starting with a special character Match occurred
例子2
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 = "\\.$";
Scanner sc = new Scanner(System.in);
System.out.println("Enter 5 input strings: ");
String input[] = new String[5];
for (int i=0; i<5; i++) {
input[i] = sc.nextLine();
}
//创建一个Pattern对象
Pattern p = Pattern.compile(regex);
for(int i=0; i<5;i++) {
//创建一个Matcher对象
Matcher m = p.matcher(input[i]);
if(m.find()) {
System.out.println("String "+i+" ends with '.'");
}
}
}
}输出结果
Enter 5 input strings: hello how are you. where do you live what is your name. welcome to nhooo The Biggest Online Tutorials Library. String 0 ends with '.' String 2 ends with '.' String 4 ends with '.'
例子3
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 = "^[A-Z]";
Scanner sc = new Scanner(System.in);
System.out.println("Enter 5 input strings: ");
String input[] = new String[5];
for (int i=0; i<5; i++) {
input[i] = sc.nextLine();
}
//创建一个Pattern对象
Pattern p = Pattern.compile(regex);
for(int i=0; i<5;i++) {
//创建一个Matcher对象
Matcher m = p.matcher(input[i]);
if(m.find()) {
System.out.println("String "+i+" starts with a capital letter");
}
}
}
}输出结果
Enter 5 input strings: Sample text1 sample text2 hello how are you Welcome to nhooo Good morning String 0 starts with a capital letter String 3 starts with a capital letter String 4 starts with a capital letter