Quantifier

In this chapter you will learn:

1. What are quantifiers in regular expressions
2. How to use + quantifier

Quantifiers

A quantifier determines how many times an expression is matched.

The quantifiers are shown here:

For example, the pattern "x+" will match "x", "xx", and "xxx".

Use + quantifier

The following example that uses the + quantifier to match any arbitrarily long sequence of As.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
//from  jav  a2 s . c o m
public class Main {
  public static void main(String args[]) {
    Pattern pat = Pattern.compile("A+");
    Matcher mat = pat.matcher("A AA AAA");
    while (mat.find()){
      System.out.println("Match: " + mat.group());
    }      
  }
}

The code above generates the following result.

The code above creates a pattern A+. + is a quantifier matching one or more. A+ means to match one A or more As, more As can be AA, AAA or AAAA...

Next chapter...

What you will learn in the next chapter:

1. How to match words start and end

Regular Expression Processing

Normal characters

Character class

Wildcard Character

Quantifier

Wildcards and Quantifiers

Character class and quantifiers

Find sub string

Multiple subsequences

Replace all

Split