Implementation of Either for Google Guava

Either

import com.google.common.base.Function;
import com.google.common.base.Optional;
import java.util.NoSuchElementException;

public abstract class Either<T, U, W> {

	public abstract boolean isLeft();

	public abstract boolean isRight();

	public abstract U getRight();

	public abstract T getLeft();

	public W fold(Function<T, W> funcLeft, Function<U, W> funcRight) {
		if (this.isRight()) {
			return funcRight.apply(this.getRight());
		} else {
			return funcLeft.apply(this.getLeft());
		}
	}
	
	public W apply(Function<U, W> funcRight) {
		if (this.isRight()) {
			return funcRight.apply(this.getRight());
		} else {
			return this;
		}
	}

	public Optional<U> getOptional(){
		if(this.isRight()) {
			return Optional.fromNullable(this.getRight());
		}else {
			return Optional.absent();
		}
	}
}

class Left<T, U, W> extends Either<T, U, W> {
	private T value;

	public Left(T value) {
		this.value = value;
	}

	@Override
	public boolean isLeft() {
		return true;
	}

	@Override
	public boolean isRight() {
		return !isLeft();
	}

	public T get() {
		return value;
	}

	@Override
	public U getRight() {
		throw new NoSuchElementException("Right can't be accessed");
	}

	@Override
	public T getLeft() {
		return get();
	}
}

class Right<T, U, W> extends Either<T, U, W> {
	private U value;

	public Right(U value) {
		this.value = value;
	}

	@Override
	public boolean isLeft() {
		return false;
	}

	@Override
	public boolean isRight() {
		return !isLeft();
	}

	public U get() {
		return value;
	}

	@Override
	public U getRight() {
		return get();
	}

	@Override
	public T getLeft() {
		throw new NoSuchElementException("Left can't be accessed");
	}
}