Intent data passer

readme.md

Basic class used to temporarily storing data to be passed between activities. As only one activity can be displayed at a time, it is reasonable to use the Activity's class name to store/retrieve data for that activity.

Usage

IntentDataHelper.getInstance().store(UsersActivity.class, getAllUsers()); // large transaction!

IntentDataHelper.getInstance().retrieve(UsersActivity.class, new TypeToken<ArrayList<User>>(){}.getClass()); // large transaction!

IntentDataHelper.java

package cube.com.helper;

import java.util.WeakHashMap;

import lombok.Getter;

/**
 * Singleton class used for passing large data sets around without having to serialise.
 * This class should <b>not</b> reference any kind of context without implicitly destroying
 * the object when it is done to prevent Context leaks. Be wary!
 *
 * @author Callum Taylor
 */
public class IntentDataHelper
{
	@Getter(lazy = true) private static final IntentDataHelper instance = new IntentDataHelper();

	private WeakHashMap<Class, Object> dataStore = new WeakHashMap<>();

	/**
	 * Stores object data against a class name. Operation is destructive, if {@param className} already exists in the data store map.
	 *
	 * @param className The class to store against, use the same class name to retrieve the data back.
	 * @param data The data to temporarily store.
	 */
	public void store(Class className, Object data)
	{
		dataStore.put(className, data);
	}

	/**
	 * Gets the stored data object from a given className, or null if nothing was stored. Operation is destructive,
	 * object will be removed from data store once retrieved.
	 *
	 * @param className The class name used to originally store the data
	 * @return The found object or null.
	 */
	public Object retrieve(Class className)
	{
		return retrieve(className, Object.class);
	}

	/**
	 * Gets the stored data object from a given className, or null if nothing was stored. Operation is destructive,
	 * object will be removed from data store once retrieved.
	 *
	 * @param className The class name used to originally store the data
	 * @param classType The class type to force cast to
	 * @return The found object or null.
	 */
	public <T> T retrieve(Class className, Class<T> classType)
	{
		return (T)classType.cast(dataStore.remove(className));
	}

	/**
	 * Force destroys the data store to remove all references
	 */
	public void clear()
	{
		dataStore = new WeakHashMap<>();
	}
}