org.wicketstuff.minis.model.IsEmptyOrNullModel.java Source code

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Here is the source code for org.wicketstuff.minis.model.IsEmptyOrNullModel.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.wicketstuff.minis.model;

import java.util.Collection;

import org.apache.wicket.model.IModel;
import org.apache.wicket.util.string.Strings;

/**
 * Model of whether the object of the dependent model is empty or null.
 *
 * @param <W>
 *            type of the dependent model
 */
public class IsEmptyOrNullModel<W> extends LoadableDetachableDependentModel<Boolean, W> {

    /**
     * Constructor.
     * 
     * @param dependentModel
     *            non-null collection model this model depends on
     */
    public IsEmptyOrNullModel(IModel<W> dependentModel) {
        super(dependentModel);
    }

    @Override
    protected Boolean load() {
        boolean empty = true;
        W dependentValue = getDependentModel().getObject();
        if (dependentValue instanceof Collection) {
            empty = ((Collection<?>) dependentValue).isEmpty();
        } else if (dependentValue instanceof CharSequence) {
            empty = Strings.isEmpty((CharSequence) dependentValue);
        } else {
            empty = dependentValue == null;
        }
        return empty;
    }

}