Scrape BTC accounts and their balance. If you see one that isn't 0.0, go to the first URL that it prints somewhere above the BTC account, and you can get the private key for that account from the page.

Main.java

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;

public class Main {
    public static void main(String[] args) throws Exception {
        for(long i = 0; i < Long.MAX_VALUE; i++) {
            System.out.println("\n[ " + "http://directory.io/" + i + " ]");
            for(String s : getBTC(i))
                System.out.println(s + " has " + getBalance(s));
        }
    }
    
    public static List<String> getBTC(long index) throws Exception {List<String> list = new ArrayList<>();for(String s : getText("http://directory.io/" + index).split(Pattern.quote("https://blockchain.info/address/")))if(!s.endsWith("</span> <a href=\"") && !s.endsWith("</html>"))list.add(s.split(Pattern.quote("\">"))[0]);List<String> list2 = new ArrayList<>();for(String s : list)if(s.length() == 33)list2.add(s + " ");else list2.add(s);list = null;return list2;}
    public static double getBalance(String address) throws Exception {return Double.parseDouble(getText("https://blockchain.info/address/" + address).split(Pattern.quote("<td id=\"final_balance\"><font color=\"green\"><span data-c=\""))[1].split(Pattern.quote("\""))[0]);}
    public static String getText(String url) throws Exception {System.setProperty("http.agent", "");URLConnection connection = new URL(url).openConnection();connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2");BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));StringBuilder response = new StringBuilder();String inputLine;while ((inputLine = in.readLine()) != null)response.append(inputLine);in.close();return response.toString();}  
}

Hello, I tried to compile the code online and I get the following errors:
[ http://directory.io/0 ] Exception in thread "main" java.net.UnknownHostException: directory.io at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) at java.net.Socket.connect(Socket.java:589) at java.net.Socket.connect(Socket.java:538) at sun.net.NetworkClient.doConnect(NetworkClient.java:180) at sun.net.www.http.HttpClient.openServer(HttpClient.java:463) at sun.net.www.http.HttpClient.openServer(HttpClient.java:558) at sun.net.www.http.HttpClient.<init>(HttpClient.java:242) at sun.net.www.http.HttpClient.New(HttpClient.java:339) at sun.net.www.http.HttpClient.New(HttpClient.java:357) at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1202) at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1138) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1032) at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:966) at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1546) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474) at Main.getText(Main.java:20) at Main.getBTC(Main.java:18) at Main.main(Main.java:13) exited with non-zero status