import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
import java.text.*;

class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String str = "Text here 1-Mar-2019 to 31-Mar-2019 and tex there";
		String startdt = "";
		String enddt = "";
		
		String date_rx = "\\d{1,2}-[a-zA-Z]{3}-\\d{4}";
		Pattern p = Pattern.compile("(" + date_rx + ")\\s*to\\s*(" + date_rx + ")");  
		Matcher m = p.matcher(str);
		if(m.find())
		{
		    startdt = m.group(1); 
		    enddt = m.group(2); 
		}
		System.out.println("startdt: "+startdt+" enddt: "+enddt);
	}
}