noderelation.java

支持并发访问的B+树

/*
 * Created on Jun 9, 2004
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
package com.nay0648.ds.bplustree;
import java.util.*;

/**
 * Description:<br>
 * &nbsp&nbsp this class is used to deal with the relationship between node
 * such as get a node's parent,get a node's brother and so on.here use an
 * List hold the node's address need to deal with,because the limit of the
 * memory,so here cache a node's address instead of cache a node.the node 
 * into this class must added in order.
 * @abstract
 * @keywords
 * @author nay0648<br>
 * if you have any questions,advices,suggests,or find any
 * bugs,please mail me: <a href="mailto:">[e-mail]</a>
 * @version last modified:Jun 9, 2004
 */
class NodeRelation
{
private List relation;

	public NodeRelation()
	{
		relation=new ArrayList();
	}
	
	/**
	 * add a node into the relation list
	 * @param addr
	 * the node's address
	 */
	public void addNode(long addr)
	{
		relation.add(new Long(addr));
	}
	
	/**
	 * get a node's parent node's address,exectaly,it's
	 * get the predecessor address of argument address,in
	 * relationship list
	 * @param addr
	 * a node's address
	 * @return
	 * return BPlusTree.NULL if this node dose not have parent
	 */
	public long getParent(long addr)
	{
		int i;
		
		for(i=0;i<relation.size();i++)
			if(((Long)relation.get(i)).longValue()==addr) break;
		if(i==0) return BPlusTree.NULL;
		else return ((Long)relation.get(i-1)).longValue();
	}
	
	public String toString()
	{
		return relation.toString();
	}
}