UIKey.java

/*
 *
 *  * Copyright (c) 2016. David Sowerby
 *  *
 *  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 *  * the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 *  *
 *  * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 *  * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 *  * specific language governing permissions and limitations under the License.
 *
 */
package uk.q3c.krail.core.guice.uiscope;

import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;

/**
 * This class is entirely passive - it is a surrogate for the UI itself during the IoC process in support of
 * {@link UIScoped}. <br>
 * <br>
 * The UI instance would normally be used as the key in @link {@link UIScope}, but this causes a problem with
 * constructor injection of a UI instance. This is because any constructor parameters which are also UIScoped are
 * created before the UI, and therefore before the UI entry in UIScope exists. To overcome this, the UI is represented
 * by a {@link UIKey}, which is available from the start of UI construction. The UI itself, and any UIScoped injections
 * are then linked by that {@link UIKey} instance.<br>
 * <br>
 * The counter value is set by the {@link UIKeyProvider}
 */
@Immutable
public class UIKey implements Comparable<UIKey> {
    private final int counter;

    public UIKey(int counter) {
        super();
        this.counter = counter;
    }

    @Override
    public String toString() {
        return "UIKey:" + counter;
    }

    @Override
    public int compareTo(@Nonnull UIKey other) {
        return this.getCounter() - other.getCounter();
    }

    public int getCounter() {
        return counter;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        UIKey uiKey = (UIKey) o;

        return counter == uiKey.counter;

    }

    @Override
    public int hashCode() {
        return counter;
    }
}