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ActiveMQ example source code file (LinkedNode.java)

This example ActiveMQ source code file (LinkedNode.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

illegalargumentexception, illegalargumentexception, linkednode, linkednodelist, linkednodelist, suppresswarnings, t, t, this, you, you

The ActiveMQ LinkedNode.java source code

/**
 * 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.apache.kahadb.util;

/**
 * Provides a base class for you to extend when you want object to maintain a
 * doubly linked list to other objects without using a collection class.
 * 
 * @author chirino
 */
public class LinkedNode<T extends LinkedNode {

    protected LinkedNodeList<T> list;
    protected T next;
    protected T prev;

    public LinkedNode() {
    }

    @SuppressWarnings("unchecked")
    private T getThis() {
        return (T) this;
    }

    public T getHeadNode() {
        return list.head;
    }

    public T getTailNode() {
        return list.head.prev;
    }

    public T getNext() {
        return isTailNode() ? null : next;
    }

    public T getPrevious() {
        return isHeadNode() ? null : prev;
    }

    public T getNextCircular() {
        return next;
    }

    public T getPreviousCircular() {
        return prev;
    }

    public boolean isHeadNode() {
        return list.head == this;
    }

    public boolean isTailNode() {
        return list.head.prev == this;
    }

    /**
     * @param node
     *            the node to link after this node.
     * @return this
     */
    public void linkAfter(T node) {
        if (node == this) {
            throw new IllegalArgumentException("You cannot link to yourself");
        }
        if (node.list != null) {
            throw new IllegalArgumentException("You only insert nodes that are not in a list");
        }
        if (list == null) {
            throw new IllegalArgumentException("This node is not yet in a list");
        }

        node.list = list;

        // given we linked this<->next and are inserting node in between
        node.prev = getThis(); // link this<-node
        node.next = next; // link node->next
        next.prev = node; // link node<-next
        next = node; // this->node
        list.size++;
    }

    /**
     * @param rightList
     *            the node to link after this node.
     * @return this
     */
    public void linkAfter(LinkedNodeList<T> rightList) {

        if (rightList == list) {
            throw new IllegalArgumentException("You cannot link to yourself");
        }
        if (list == null) {
            throw new IllegalArgumentException("This node is not yet in a list");
        }

        T rightHead = rightList.head;
        T rightTail = rightList.head.prev;
        list.reparent(rightList);

        // given we linked this<->next and are inserting list in between
        rightHead.prev = getThis(); // link this<-list
        rightTail.next = next; // link list->next
        next.prev = rightTail; // link list<-next
        next = rightHead; // this->list
    }

    /**
     * @param node
     *            the node to link after this node.
     * @return
     * @return this
     */
    public void linkBefore(T node) {

        if (node == this) {
            throw new IllegalArgumentException("You cannot link to yourself");
        }
        if (node.list != null) {
            throw new IllegalArgumentException("You only insert nodes that are not in a list");
        }
        if (list == null) {
            throw new IllegalArgumentException("This node is not yet in a list");
        }

        node.list = list;

        // given we linked prev<->this and are inserting node in between
        node.next = getThis(); // node->this
        node.prev = prev; // prev<-node
        prev.next = node; // prev->node
        prev = node; // node<-this

        if (this == list.head) {
            list.head = node;
        }
        list.size++;
    }

    /**
     * @param leftList
     *            the node to link after this node.
     * @return
     * @return this
     */
    public void linkBefore(LinkedNodeList<T> leftList) {

        if (leftList == list) {
            throw new IllegalArgumentException("You cannot link to yourself");
        }
        if (list == null) {
            throw new IllegalArgumentException("This node is not yet in a list");
        }

        T leftHead = leftList.head;
        T leftTail = leftList.head.prev;
        list.reparent(leftList);

        // given we linked prev<->this and are inserting list in between
        leftTail.next = getThis(); // list->this
        leftHead.prev = prev; // prev<-list
        prev.next = leftHead; // prev->list
        prev = leftTail; // list<-this

        if (isHeadNode()) {
            list.head = leftHead;
        }
    }

    public void linkToTail(LinkedNodeList<T> target) {
        if (list != null) {
            throw new IllegalArgumentException("This node is already linked to a node");
        }

        if (target.head == null) {
            next = prev = target.head = getThis();
            list = target;
            list.size++;
        } else {
            target.head.prev.linkAfter(getThis());
        }
    }

    public void linkToHead(LinkedNodeList<T> target) {
        if (list != null) {
            throw new IllegalArgumentException("This node is already linked to a node");
        }

        if (target.head == null) {
            next = prev = target.head = getThis();
            list = target;
            list.size++;
        } else {
            target.head.linkBefore(getThis());
        }
    }

    /**
     * Removes this node out of the linked list it is chained in.
     */
    public boolean unlink() {

        // If we are allready unlinked...
        if (list == null) {
            return false;
        }

        if (getThis() == prev) {
            // We are the only item in the list
            list.head = null;
        } else {
            // given we linked prev<->this<->next
            next.prev = prev; // prev<-next
            prev.next = next; // prev->next

            if (isHeadNode()) {
                list.head = next;
            }
        }
        list.size--;
        list = null;
        return true;
    }

    /**
     * Splits the list into 2 lists. This node becomes the tail of this list.
     * Then 2nd list is returned.
     * 
     * @return An empty list if this is a tail node.
     */
    public LinkedNodeList<T> splitAfter() {

        if (isTailNode()) {
            return new LinkedNodeList<T>();
        }

        // Create the new list
        LinkedNodeList<T> newList = new LinkedNodeList();
        newList.head = next;

        // Update the head and tail of the new list so that they point to each
        // other.
        newList.head.prev = list.head.prev; // new list: tail<-head
        newList.head.prev.next = newList.head; // new list: tail->head
        next = list.head; // old list: tail->head
        list.head.prev = getThis(); // old list: tail<-head

        // Update all the nodes in the new list so that they know of their new
        // list owner.
        T n = newList.head;
        newList.size++;
        list.size--;
        do {
            n.list = newList;
            n = n.next;
            newList.size++;
            list.size--;
        } while (n != newList.head);

        return newList;
    }

    /**
     * Splits the list into 2 lists. This node becomes the head of this list.
     * Then 2nd list is returned.
     * 
     * @return An empty list if this is a head node.
     */
    public LinkedNodeList<T> splitBefore() {

        if (isHeadNode()) {
            return new LinkedNodeList<T>();
        }

        // Create the new list
        LinkedNodeList<T> newList = new LinkedNodeList();
        newList.head = list.head;
        list.head = getThis();

        T newListTail = prev;

        prev = newList.head.prev; // old list: tail<-head
        prev.next = getThis(); // old list: tail->head
        newList.head.prev = newListTail; // new list: tail<-head
        newListTail.next = newList.head; // new list: tail->head

        // Update all the nodes in the new list so that they know of their new
        // list owner.
        T n = newList.head;
        newList.size++;
        list.size--;
        do {
            n.list = newList;
            n = n.next;
            newList.size++;
            list.size--;
        } while (n != newList.head);

        return newList;
    }

    public boolean isLinked() {
        return list != null;
    }

	public LinkedNodeList<T> getList() {
		return list;
	}

}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ LinkedNode.java source code file:

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