Dear Sirs,

I'm starting to write a strategy, which, after adding a little class parsing string to hash, compiles without errors, but the strategy says "class not found".

I am new to Java and Jforex, so any link to manual will be greately appreciated.

Here is the class I added:

private class ServerInfo {
    private HashMap indexValues;
    private HashMap indexColors;

    public String fill(String desc) { // Создаёт класс из описателя
   String rv;

   rv = "";
   Pattern pattern = Pattern.compile("\\s*([\\d\\w]+)\\s*=\\s*([^;]+);");
   Matcher matcher = pattern.matcher(desc);
   while (matcher.find()) {
       String par = matcher.group(1);
       if(par == "CMD") {
      rv = matcher.group(2);
       }
       else {
      indexValues.put(par,new String(matcher.group(2)));
       }
   }
   return rv;
    }

    public ServerInfo(String desc) { // Заполняет значения из описателя
   Pattern pattern = Pattern.compile("\\s*([\\d\\w]+)\\s*=\\s*([^;]+);");
   Matcher matcher = pattern.matcher(desc);
   while (matcher.find()) {
       indexColors.put(matcher.group(1),new String(matcher.group(2)));
   }
    }

    public String get(String index) {
   return (String) indexValues.get(index);
    }
}

Consider trying something like this:

package jforex.test;

import java.util.HashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.dukascopy.api.*;

public class StratWithClass implements IStrategy {
    
    @Override
    public void onStart(IContext context) throws JFException {
        ServerInfo serverInfo = new ServerInfo("some string");
    }

    @Override
    public void onTick(Instrument instrument, ITick tick) throws JFException {}

    @Override
    public void onBar(Instrument instrument, Period period, IBar askBar, IBar bidBar) throws JFException {}

    @Override
    public void onMessage(IMessage message) throws JFException {}

    @Override
    public void onAccount(IAccount account) throws JFException {}

    @Override
    public void onStop() throws JFException {}

    private class ServerInfo {
        private HashMap indexValues;
        private HashMap indexColors;

        public String fill(String desc) { 
            String rv;

            rv = "";
            Pattern pattern = Pattern.compile("\\s*([\\d\\w]+)\\s*=\\s*([^;]+);");
            Matcher matcher = pattern.matcher(desc);
            while (matcher.find()) {
                String par = matcher.group(1);
                if (par == "CMD") {
                    rv = matcher.group(2);
                } else {
                    indexValues.put(par, new String(matcher.group(2)));
                }
            }
            return rv;
        }

        public ServerInfo(String desc) { 
            Pattern pattern = Pattern.compile("\\s*([\\d\\w]+)\\s*=\\s*([^;]+);");
            Matcher matcher = pattern.matcher(desc);
            while (matcher.find()) {
                indexColors.put(matcher.group(1), new String(matcher.group(2)));
            }
        }

        public String get(String index) {
            return (String) indexValues.get(index);
        }
    }

}

Thank you, this worked, but I think I need this class to be external to use it in an indicator as well as in strategy. Is it possible?
Or, alternatively, is it possible for strategy to draw not in the chart window, but in a separate one, as index does?

Yes, you can either load the class file:
https://www.dukascopy.com/wiki/#Load_java_class
Or a jar file:
https://www.dukascopy.com/wiki/#Include_libraries
Currently from strategy it is only possible to draw only on the main chart window.