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How to match beginning of a particular string/line using Java RegEx
The meta character “^” matches the beginning of a particular string i.e. it matches the first character of the string. For example,
The expression “^\d” matches the string/line starting with a digit.
The expression “^[a-z]” matches the string/line starting with a lower case alphabet.
Example 1
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Example {
public static void main(String args[]) {
//Reading String from user
System.out.println("Enter a String");
Scanner sc = new Scanner(System.in);
String input = sc.nextLine();
String regex = "^[^a-zA-Z0-9//s].*";
//Compiling the regular expression
Pattern pattern = Pattern.compile(regex);
//Retrieving the matcher object
Matcher matcher = pattern.matcher(input);
if(matcher.matches()) {
System.out.println("Match occurred");
} else {
System.out.println("Match not occurred");
}
}
}Output
Enter a String #starting with a special character Match occurred
Example 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();
}
//Creating a Pattern object
Pattern p = Pattern.compile(regex);
for(int i=0; i<5;i++) {
//Creating a Matcher object
Matcher m = p.matcher(input[i]);
if(m.find()) {
System.out.println("String "+i+" ends with '.'");
}
}
}
}Output
Enter 5 input strings: hello how are you. where do you live what is your name. welcome to tutorialspoint The Biggest Online Tutorials Library. String 0 ends with '.' String 2 ends with '.' String 4 ends with '.'
Example 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();
}
//Creating a Pattern object
Pattern p = Pattern.compile(regex);
for(int i=0; i<5;i++) {
//Creating a Matcher object
Matcher m = p.matcher(input[i]);
if(m.find()) {
System.out.println("String "+i+" starts with a capital letter");
}
}
}
}Output
Enter 5 input strings: Sample text1 sample text2 hello how are you Welcome to tutorialspoint Good morning String 0 starts with a capital letter String 3 starts with a capital letter String 4 starts with a capital letter
Updated on: 19-Nov-2019
9K+ Views
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