KeyGeneratorImpl.java

package course.examples.Services.KeyService;

import java.util.HashSet;
import java.util.Set;
import java.util.UUID;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import course.examples.Services.KeyCommon.KeyGenerator;

public class KeyGeneratorImpl extends Service {

	// Set of already assigned IDs
	// Note: These keys are not guaranteed to be unique if the Service is killed 
	// and restarted.
	
	private final static Set<UUID> mIDs = new HashSet<UUID>();

	// Implement the Stub for this Object
	private final KeyGenerator.Stub mBinder = new KeyGenerator.Stub() {
	
		// Implement the remote method
		public String getKey() {
		
			UUID id;
			
			// Acquire lock to ensure exclusive access to mIDs 
			// Then examine and modify mIDs
			
			synchronized (mIDs) {
				
				do {
				
					id = UUID.randomUUID();
				
				} while (mIDs.contains(id));

				mIDs.add(id);
			}
			return id.toString();
		}
	};

	// Return the Stub defined above
	@Override
	public IBinder onBind(Intent intent) {
		return mBinder;
	}
}