Android application time synchronization, using android.os.SystemClock

ServerDate.java

import android.os.SystemClock;
import java.util.Date;

/**
 * Created by tankcong
 */
public class ServerDate {

  private Date serverDate;

  private long initElapsedTime;

  private static ServerDate INSTANCE;

  public static ServerDate getInstance() {
    if (INSTANCE == null) {
      INSTANCE = new ServerDate();
    }
    return INSTANCE;
  }

  public boolean synced() {
    return serverDate != null;
  }

  /**
   * simple implementation, just set server date,
   * replace with time synchronization logic.
   */
  public void syncServer(Date serverDate) {
    initElapsedTime = SystemClock.elapsedRealtime();
    this.serverDate = serverDate;
  }

  public Date currentDateGMT() {
    Date current = new Date(serverDate.getTime());
    current.setTime(serverDate.getTime()
        + (SystemClock.elapsedRealtime() - initElapsedTime));
    return current;
  }

}