JAVA 树中 按最长路径行驶

 private Vector findRoad(int posX,int posY,int dir){
        Vector roadUPVec=null,roadRIGHTVec=null,roadDOWNVec=null,roadLEFTVec=null;
        boolean tempUP=false,tempRIGHT=false,tempLEFT=false,tempDOWN=false;
        int upNum=0,downNum=0,rightNum=0,leftNum=0,maxNum=0;
       
        if(posY>0 && m_nowMap[posX][posY-1]!=0 && dir!=DIR_UP){
            roadUPVec=new Vector();
            roadUPVec.addElement(new Integer(posX));
            roadUPVec.addElement(new Integer(posY-1));
            Vector tempVec=findRoad(posX,posY-1,DIR_DOWN);
            if(tempVec!=null){
                for(int i=0;i<tempVec.size();i++)
                    roadUPVec.addElement(tempVec.elementAt(i));
            }
        }
        else
            tempUP=false;
        if(posX<COLUMN-1 && m_nowMap[posX+1][posY]!=0 && dir!=DIR_RIGHT){
            roadRIGHTVec=new Vector();
            roadRIGHTVec.addElement(new Integer(posX+1));
            roadRIGHTVec.addElement(new Integer(posY));
            Vector tempVec=findRoad(posX+1,posY,DIR_LEFT);
            if(tempVec!=null){
                for(int i=0;i<tempVec.size();i++)
                    roadRIGHTVec.addElement(tempVec.elementAt(i));
            }
        }
        else
            tempRIGHT=false;
        if(posY<ROW && m_nowMap[posX][posY+1]!=0 && dir!=DIR_DOWN){
            roadDOWNVec=new Vector();