Search Minecraft profiles by name or UUID. Requires Gson.

Profile.java

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;

import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

public class Profile {

    private final String username;
    private final String uuid;

    private Profile(String username, String uuid) {
        this.username = username;
        this.uuid = uuid;
    }
    
    public String getUsername() {
        return username;
    }
    
    public String getUuid() {
        return uuid;
    }
    
    @Override
    public String toString() {
        return "Profile{username=" + username + ",uuid=" + uuid + "}";
    }

    public static List<Profile> findByName(List<String> names) throws Exception {
        List<Profile> list = new ArrayList<Profile>(names.size());
        int requests = 1;
        for (int i = 0; i < requests; i++) {
            HttpURLConnection connection = getNameConnection();
            String body = new Gson().toJson(names.subList(i * 100, Math.min((i + 1) * 100, names.size())));
            OutputStream stream = connection.getOutputStream();
            stream.write(body.getBytes());
            stream.flush();
            stream.close();
            JsonArray array = new Gson().fromJson(new InputStreamReader(connection.getInputStream()), JsonArray.class);
            for (Object profile : array) {
                JsonObject jsonProfile = (JsonObject) profile;
                String name = jsonProfile.get("name").getAsString();
                String id = jsonProfile.get("id").getAsString();
                list.add(new Profile(name, id));
            }
        }
        return list;
    }

    public static List<Profile> findbyUuid(List<String> uuids) throws Exception {
        List<Profile> list = new ArrayList<Profile>();
        for (String uuid : uuids) {
            HttpURLConnection connection = getUUIDConnection(uuid);
            JsonArray array = new Gson().fromJson(new InputStreamReader(connection.getInputStream()), JsonArray.class);
            if (array.size() > 0)
                list.add(new Profile(array.get(0).getAsJsonObject().get("name").getAsString(), uuid));
        }
        return list;
    }
    
    private static HttpURLConnection getNameConnection() throws Exception {
        URL url = new URL("https://api.mojang.com/profiles/minecraft");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setUseCaches(false);
        connection.setDoOutput(true);
        return connection;
    }
    
    private static HttpURLConnection getUUIDConnection(String uuid) throws Exception {
        URL url = new URL("https://api.mojang.com/user/profiles/" + uuid + "/names");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setUseCaches(false);
        connection.setDoOutput(true);
        return connection;
    }
}

ProfileExample.java

import java.util.ArrayList;
import java.util.List;
import java.util.Arrays;

public class ProfileExample {
    public static void main(String... args) {
        // Username
        List<Profile> profiles = Profile.findByName(Arrays.asList("swivr", "Notch"));
        System.out.println(profiles);
        
        // Uuid
        profiles = Profile.findByUuid(Arrays.asList("df91bff5b7e54b54b7d4463efadac146", "069a79f444e94726a5befca90e38aaf5"));
        System.out.println(profiles);
    }
}