# Find all the patterns of “1(0+)1” in a given string | SET 2(Regular Expression Approach)

In Set 1, we have discussed general approach for counting the patterns of the form 1(0+)1 where (0+) represents any non-empty consecutive sequence of 0’s.In this post, we will discuss regular expression approach to count the same.

**Examples:**

Input : 1101001 Output : 2 Input : 100001abc101 Output : 2

Below is one of the regular expression for above pattern

10+1

Hence, whenever we found a match, we increase counter for counting the pattern.As last character of a match will always ‘1’, we have to again start searching from that index.

`//Java program to count the patterns ` `// of the form 1(0+)1 using Regex` ` ` `import` `java.util.regex.Matcher;` `import` `java.util.regex.Pattern;` ` ` `class` `GFG ` `{` ` ` `static` `int` `patternCount(String str) ` ` ` `{` ` ` `// regular expression for the pattern` ` ` `String regex = ` `"10+1"` `;` ` ` ` ` `// compiling regex` ` ` `Pattern p = Pattern.compile(regex);` ` ` ` ` `// Matcher object` ` ` `Matcher m = p.matcher(str);` ` ` ` ` `// counter` ` ` `int` `counter = ` `0` `;` ` ` ` ` `// whenever match found` ` ` `// increment counter` ` ` `while` `(m.find())` ` ` `{` ` ` `// As last character of current match` ` ` `// is always one, starting match from that index` ` ` `m.region(m.end()-` `1` `, str.length());` ` ` ` ` `counter++;` ` ` `}` ` ` ` ` `return` `counter;` ` ` `}` ` ` ` ` `// Driver Method` ` ` `public` `static` `void` `main (String[] args)` ` ` `{` ` ` `String str = ` `"1001ab010abc01001"` `;` ` ` `System.out.println(patternCount(str));` ` ` `}` `}` |

Output:

2

**Related Articles :**

- Regular Expression Java
- Quantifiers
- Extracting each word from a String using Regex
- Check if a given string is a valid number (Integer or Floating Point)
- Print first letter of each word in a string using regex

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