Android Open Source - khandroid State Machine Impl

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License

The source code is released under:

Apache License

Java Source Code

package com.github.khandroid.state;
//  ww  w . java 2 s.  c o m
import org.slf4j.LoggerFactory;


public class StateMachineImpl implements StateMachine {
    private volatile State mCurrentState;
    private volatile State mGlobalState;
    private volatile State mPreviousState;
    
    private final org.slf4j.Logger mLogger = LoggerFactory.getLogger(StateMachineImpl.class.getSimpleName());
    
    @Override
    public synchronized void switchToState(State newState) {
        if (newState == null) {
            throw new IllegalArgumentException("state is null");
        }
        
        if (mCurrentState != null) {
            mCurrentState.onExit();
            mPreviousState = mCurrentState;
        }
        
        mCurrentState = newState;
        mCurrentState.onEnter();
    }


    @Override
    public synchronized void revertToPreviousState() {
        if (mPreviousState != null) {
            switchToState(mPreviousState);    
        } else {
            throw new IllegalStateException("No previous state to switch to");
        }
    }


    @Override
    public void setGlobalState(State state) {
        mGlobalState = state;
    }


    @Override
    public State getCurrentState() {
        return mCurrentState;
    }


    @Override
    public State getGlobalState() {
        return mGlobalState;
    }


    @Override
    public boolean isInState(State state) {
        if (state == mCurrentState) {
             return true;
        } else {
            return false;
        }
    }


    @Override
    public synchronized boolean handleEvent(StateEvent event) {
        boolean ret = mCurrentState.handleEvent(event); 
        if (!ret) {
            if (mGlobalState != null) {
                ret = mGlobalState.handleEvent(event);
                if (!ret) {
                    mLogger.warn("Unhandled event {} in state {}, global state {}", 
                                event.getClass().getSimpleName(), 
                                mCurrentState.getClass().getSimpleName(),
                                mGlobalState.getClass().getSimpleName());
                }
            } else {
                mLogger.warn("Unhandled event {} in state {}, global state not set", 
                            event.getClass().getSimpleName(), 
                            mCurrentState.getClass().getSimpleName());
            }
        }
        
        return ret;
    }
}

Java Source Code List

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