Regular Expression Search Program

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.

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);
}
}