Regular Expression Search Program

Regular Expression: Regular Expression is used to perform many string related operations. This is the way to manipulate different kind of operations like search, edit and manipulating string can be performed by the regular expression. It has both type characters (literal characters and meta characters). In this section, you will learn how to search a string from the given string exactly.

Program Result: Following program gives you the search facility in which it takes two string/text. One is searched in another one text or string and tells you for the occurrence of the given string for searching into a long string. If the string does not lies in the given string from which the string has to be searched.

Code Description

Pattern:
This is the class of the java.util.regex package which is the compiled representation. Specified string is first compiled into an instance of this class. The pattern to be used to create a matcher object which finds the character sequences for the regular expression.

Matcher:
This is also a class of java.util.regex package which is used to match character sequences.

matcher.find():
Above method finds the matched string in the given string for searching. This method returns a boolean value either true or false.

Here is the code of the program:


import java.util.regex.*;

import java.io.*;



public class SearchProgram{

  public static void main(String[] args) throws IOException{

    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    System.out.print("Enter string in which we have to search: ");

    String string = in.readLine();

    System.out.print("Enter string to search: ");

    String str = in.readLine();

    Pattern pattern = Pattern.compile(str);

    Matcher matcher = pattern.matcher(string);

    int a = 0;

    while(matcher.find()){

      a = a + 1;

    }

    if(a == 0)

      System.out.println("Word not found.");

    else

      System.out.println("Occurrence of the word is: " + a);

  }

}

Download this example.

Output of the program:

C:\java\util>java SearchProgram
Enter string in which we have to search: dtwerb wewrvwervwe chandan
Enter string to search: w
Occurrence of the word is: 5

C:\java\util>_

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