Question

How to use X+ , X+? and X++ regular expressions (REGEX) in Java

Answer 1

package javaapplication1;
  
import java.util.regex.Matcher;
import java.util.regex.Pattern;
  
public class Example {
    public static void main(String[] args) {
        // X+ , X+? and	X++  (X one or more times)
        searchREGEX("", "a+", "a+?", "a++");
    }
      
    private static void searchREGEX(String input, String... regex_list) {
        for (String regex : regex_list) {
            Pattern pattern = Pattern.compile(regex);
            Matcher matcher = pattern.matcher(input);
   
            boolean found = false;
            while (matcher.find()) {
               System.out.println(String.format("%s: Found" + " \"%s\" " + "from index %d to %d",
                                       regex, matcher.group(), matcher.start(), matcher.end()));
               found = true;
            }
            System.out.println();
            if (!found) 
                System.out.println("Not found");
        }
    }
}
  
  
/*
run:
   
Not found

Not found

Not found
   
*/

 

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Answer 2

package javaapplication1;
  
import java.util.regex.Matcher;
import java.util.regex.Pattern;
  
public class Example {
    public static void main(String[] args) {
        // X+ , X+? and	X++  (X one or more times)
        searchREGEX("a", "a+", "a+?", "a++");
    }
      
    private static void searchREGEX(String input, String... regex_list) {
        for (String regex : regex_list) {
            Pattern pattern = Pattern.compile(regex);
            Matcher matcher = pattern.matcher(input);
   
            boolean found = false;
            while (matcher.find()) {
               System.out.println(String.format("%s: Found" + " \"%s\" " + "from index %d to %d",
                                       regex, matcher.group(), matcher.start(), matcher.end()));
               found = true;
            }
            System.out.println();
            if (!found) 
                System.out.println("Not found");
        }
    }
}
  
  
/*
run:
   
a+: Found "a" from index 0 to 1

a+?: Found "a" from index 0 to 1

a++: Found "a" from index 0 to 1
   
*/

 

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Answer 3

package javaapplication1;
  
import java.util.regex.Matcher;
import java.util.regex.Pattern;
  
public class Example {
    public static void main(String[] args) {
        // X+ , X+? and	X++  (X one or more times)
        searchREGEX("aa", "a+", "a+?", "a++");
    }
      
    private static void searchREGEX(String input, String... regex_list) {
        for (String regex : regex_list) {
            Pattern pattern = Pattern.compile(regex);
            Matcher matcher = pattern.matcher(input);
   
            boolean found = false;
            while (matcher.find()) {
               System.out.println(String.format("%s: Found" + " \"%s\" " + "from index %d to %d",
                                       regex, matcher.group(), matcher.start(), matcher.end()));
               found = true;
            }
            System.out.println();
            if (!found) 
                System.out.println("Not found");
        }
    }
}
  
  
/*
run:
   
a+: Found "aa" from index 0 to 2

a+?: Found "a" from index 0 to 1
a+?: Found "a" from index 1 to 2

a++: Found "aa" from index 0 to 2
   
*/

 

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Answer 4

package javaapplication1;
  
import java.util.regex.Matcher;
import java.util.regex.Pattern;
  
public class Example {
    public static void main(String[] args) {
        // X+ , X+? and	X++  (X one or more times)
        searchREGEX("aba", "a+", "a+?", "a++");
    }
      
    private static void searchREGEX(String input, String... regex_list) {
        for (String regex : regex_list) {
            Pattern pattern = Pattern.compile(regex);
            Matcher matcher = pattern.matcher(input);
   
            boolean found = false;
            while (matcher.find()) {
               System.out.println(String.format("%s: Found" + " \"%s\" " + "from index %d to %d",
                                       regex, matcher.group(), matcher.start(), matcher.end()));
               found = true;
            }
            System.out.println();
            if (!found) 
                System.out.println("Not found");
        }
    }
}
  
  
/*
run:
   
a+: Found "a" from index 0 to 1
a+: Found "a" from index 2 to 3

a+?: Found "a" from index 0 to 1
a+?: Found "a" from index 2 to 3

a++: Found "a" from index 0 to 1
a++: Found "a" from index 2 to 3
   
*/

 

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Answer 5

package javaapplication1;
  
import java.util.regex.Matcher;
import java.util.regex.Pattern;
  
public class Example {
    public static void main(String[] args) {
        // X+ , X+? and	X++  (X one or more times)
        searchREGEX("abaaa", "a+", "a+?", "a++");
    }
      
    private static void searchREGEX(String input, String... regex_list) {
        for (String regex : regex_list) {
            Pattern pattern = Pattern.compile(regex);
            Matcher matcher = pattern.matcher(input);
   
            boolean found = false;
            while (matcher.find()) {
               System.out.println(String.format("%s: Found" + " \"%s\" " + "from index %d to %d",
                                       regex, matcher.group(), matcher.start(), matcher.end()));
               found = true;
            }
            System.out.println();
            if (!found) 
                System.out.println("Not found");
        }
    }
}
  
  
/*
run:
   
a+: Found "a" from index 0 to 1
a+: Found "aaa" from index 2 to 5

a+?: Found "a" from index 0 to 1
a+?: Found "a" from index 2 to 3
a+?: Found "a" from index 3 to 4
a+?: Found "a" from index 4 to 5

a++: Found "a" from index 0 to 1
a++: Found "aaa" from index 2 to 5
   
*/

 

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