(Android) Use to check check if a threshold has expired since a last event. e.g. 5 mins has expired since the lat time some data has been downloaded. Optional persistant storage.

SimpleTimerThreshold.java

package uk.co.digitaljigsaw.utils;

import java.util.Calendar;
import java.util.Date;

import android.R.string;
import android.content.Context;
import android.content.SharedPreferences;


/**
 * 
 * Use to check check if a threshold has expired since a last event.
 *  e.g. 5 mins has expired since the last time some data has been downloaded.  
 *  
 *  This has optional caching which is set up by providing a context and 
 *  a reference name.
 * 
 * @author rob
 *
 */
public class SimpleTimerThreshold {

	private int _timeoutThresholdSeconds;
	private Date _timeoutDate;
	private SharedPreferences _preferences;
	private String _referenceName;

	// Private to hide no- paramerter constructor
	private SimpleTimerThreshold() {}


	/**
	 * Creates a new timer, 
	 * call restartTimer() 
	 * then later check if the amout of time has elapsed
	 * by calling hasTimerPassedThreshold()
	 * 
	 * @param timeThresholdSeconds
	 * 			How long the timer should be.
	 */
	public SimpleTimerThreshold(int timeThresholdSeconds) {
		_timeoutThresholdSeconds = timeThresholdSeconds;
	}
	
	
	/**
	 * Creates a new timer, with caching enabled
	 * call restartTimer() 
	 * then later check if the amout of time has elapsed
	 * by calling hasTimerPassedThreshold()
	 * 
	 * @param timeThresholdSeconds
	 * 			How long the timer should be.
	 */
	public SimpleTimerThreshold(int timeThresholdSeconds, Context context, String referenceName) {
		_timeoutThresholdSeconds = timeThresholdSeconds;
		
		_preferences = context.getSharedPreferences("SimpleTimerThreshold", 0);
		_referenceName = referenceName;
		
		Long dateLong = _preferences.getLong(_referenceName, 0);
		if (dateLong != 0) 
		{
			_timeoutDate = new Date(dateLong);
		}
	}

	/**
	 *  Call this to start / reset the timer
	 */
	public void restartTimer() {

		// Get a refrence to the Calendar singleton
		Calendar calendar = Calendar.getInstance();

		// Record the current time
		calendar.setTime(new Date());

		// Add on X seconds
		calendar.add(Calendar.SECOND, _timeoutThresholdSeconds);

		// Save the expire time
		_timeoutDate = calendar.getTime();

		// If the cache is set up save the expire date to the cache
		if (_preferences != null && _referenceName != null) 
		{
			_preferences.edit().putLong(_referenceName, _timeoutDate.getTime());
		}
		
		//Log.v(TAG, "TimeOutDate:" +_timeOutDate.toString()); 
	}


	/**
	 *  Determins if the given amout of time has expired 
	 *  since the timer was last started / reset.
	 */
	public boolean hasTimerPassedThreshold() {

		if (_timeoutDate == null) return false;

		// Get the current time
		Date now = new Date();

		//Log.v(TAG, "Now:" + now.toString());
		//Log.v(TAG, "TimeOutDate:" + _timeOutDate.toString());

		// Compare it to the timeout time
		return (now.after(_timeoutDate));
	}

}