Today i'm gonna share one of many possible ways to acquire a lock with the intent of synchronize transitions or whatever task you may have. I use it to synchronize complex animation transition sequences in Android.
import java.util.HashSet;
import java.util.Set;
/**
* Use this class to synchronize transitions, animations or whatever you want.
* It is designed to acquire and release a synchronized lock state, coordinating
* the access of it in a multi thread environment.
*
* @author Ricardo Ferreira 04/11/2013
*/
public class StateLock {
private final static StateLock INSTANCE = new StateLock();
private Set lockSet = new HashSet();
private boolean lock = false;
private StateLock() {
// singleton
}
/** Synchronized because the lock state should be acquired and released in a controlled way */
public synchronized static StateLock getInstance() {
return StateLock.INSTANCE;
}
public synchronized boolean isStateLocked() {
return lock;
}
public synchronized boolean hasStateAlreadyLocked(String stateSimpleClassName) {
return lockSet.contains(stateSimpleClassName);
}
/** Returns true if the state lock was acquired by the given class, false otherwise */
public synchronized boolean acquireLockState(String stateSimpleClassName) {
boolean operationResult = false;
if (lockSet.isEmpty()) {
lockSet.add(stateSimpleClassName);
lock = true;
operationResult = true;
}
return operationResult;
}
/** Returns true if the lock was released or no state was locked, false otherwise */
public synchronized boolean releaseLockState(String stateSimpleClassName) {
boolean operationResult = false;
if (lockSet.contains(stateSimpleClassName)) {
lockSet.clear();
lock = false;
operationResult = true;
} else if (lockSet.isEmpty()) {
lock = false;
operationResult = true;
}
return operationResult;
}
protected Object clone() throws CloneNotSupportedException {
throw new CloneNotSupportedException();
}
}
