Missing Manuals: Waiting without Espresso idling resources.

README.md

Sample: Wait for Service

Wait loginComplete = new Wait() {
  @Override
  public Boolean apply() {
    return Service.isLogin() == true;
   }
};

Wait.until(loginComplete);

Sample: Wait for UI

Wait playlistUpdated = new Wait() {
  @Override
  public Boolean apply() {
    try {
      onView(withText("華語速爆新歌 (每週二五更新)")).check(matches(isDisplayed()));
    } catch (NoMatchingViewException e) {
      // keep waiting
      return false;
    }
    
    // complete
    return true;
  }
};

assertTrue(Wait.until(playlistUpdated));

Wait.java

import android.os.SystemClock;

public abstract class Wait {
    public abstract Boolean apply();

    public static Boolean until(WaitCondition condition) {
        long startTime = SystemClock.uptimeMillis();

        Boolean result = condition.apply();
        for (long elapsedTime = 0; result == null || result.equals(false);
             elapsedTime = SystemClock.uptimeMillis() - startTime) {

            if (elapsedTime >= 2000) {
                break;
            }

            SystemClock.sleep(500);
            result = condition.apply();
        }
        return result;
    }
}