start() method with examples in Java

java.util.regex.Matcher class represents an engine for executing various matching operations. This class has no constructor and can be used withmatches()created by the method of java.util.regex.Pattern class/Get the object of this class.

The method of Matcher classstart()The method returns the starting index of the matched character.

Example

subexpression "[...]" to match the specified characters within the curly braces in the input string. In the following example, use this expression to match the character 't'. Here,

• We have used thecompile()The method compiles the regular expression.

• Get Matcher object.

• matcher()Call this method on each match item.

Example

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class StartExample {
　　　public static void main(String[] args) {
　　　　　　Scanner sc = new Scanner(System.in);
　　　　　　System.out.println("Enter input text:");
　　　　　　String input = sc.nextLine();
　　　　　　String regex = "[t]";
　　　　　　//Create a pattern object
　　　　　　Pattern pattern = Pattern.compile(regex);
　　　　　　//Match the compiled pattern in the string
　　　　　　Matcher matcher = pattern.matcher(input);
　　　　　　int count = 0;
　　　　　　while (matcher.find()) {
　　　　　　　　　int start = matcher.start();
　　　　　　　　　System.out.println(start);
　　　　　　}
　　　}
}

Output Result

Enter input text:
Hello, how are you? Welcome to w3codebox
26
31
42

Since the character 't' appears three times in the input string, you can observe three index values (representing the index of each character).