org.springframework.beans.factory.support.ManagedList.java Source code

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Here is the source code for org.springframework.beans.factory.support.ManagedList.java

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/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.beans.factory.support;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.BeanMetadataElement;
import org.springframework.beans.Mergeable;
import org.springframework.lang.Nullable;

/**
 * Tag collection class used to hold managed List elements, which may
 * include runtime bean references (to be resolved into bean objects).
 *
 * @author Rod Johnson
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 27.05.2003
 * @param <E> the element type
 */
@SuppressWarnings("serial")
public class ManagedList<E> extends ArrayList<E> implements Mergeable, BeanMetadataElement {

    @Nullable
    private Object source;

    @Nullable
    private String elementTypeName;

    private boolean mergeEnabled;

    public ManagedList() {
    }

    public ManagedList(int initialCapacity) {
        super(initialCapacity);
    }

    /**
     * Set the configuration source {@code Object} for this metadata element.
     * <p>The exact type of the object will depend on the configuration mechanism used.
     */
    public void setSource(@Nullable Object source) {
        this.source = source;
    }

    @Override
    @Nullable
    public Object getSource() {
        return this.source;
    }

    /**
     * Set the default element type name (class name) to be used for this list.
     */
    public void setElementTypeName(String elementTypeName) {
        this.elementTypeName = elementTypeName;
    }

    /**
     * Return the default element type name (class name) to be used for this list.
     */
    @Nullable
    public String getElementTypeName() {
        return this.elementTypeName;
    }

    /**
     * Set whether merging should be enabled for this collection,
     * in case of a 'parent' collection value being present.
     */
    public void setMergeEnabled(boolean mergeEnabled) {
        this.mergeEnabled = mergeEnabled;
    }

    @Override
    public boolean isMergeEnabled() {
        return this.mergeEnabled;
    }

    @Override
    @SuppressWarnings("unchecked")
    public List<E> merge(@Nullable Object parent) {
        if (!this.mergeEnabled) {
            throw new IllegalStateException(
                    "Not allowed to merge when the 'mergeEnabled' property is set to 'false'");
        }
        if (parent == null) {
            return this;
        }
        if (!(parent instanceof List)) {
            throw new IllegalArgumentException("Cannot merge with object of type [" + parent.getClass() + "]");
        }
        List<E> merged = new ManagedList<>();
        merged.addAll((List<E>) parent);
        merged.addAll(this);
        return merged;
    }

}