private static HashMap<String,ArrayList<String>> tmpMap=new  HashMap<String,ArrayList<String>>();
    private static void putData(String pid,String id)
    {
        ArrayList<String> childList=tmpMap.get(pid);
        if(childList==null)
        {
            childList=new ArrayList<String>();
            tmpMap.put(pid, childList);
        }
        childList.add(id);
    }
    private static void makeTree(String pid,int level)
    {
        System.out.println("level:"+level+","+pid);
        ArrayList<String> childList=tmpMap.get(pid);
        if(childList!=null)
        {
            for(int i=0;i<childList.size();i++)
            {
                makeTree(childList.get(i),level+1);
            }
        }
    }
    public static void main(String[] args) {
        putData("A","B");
        putData("A","C");
        putData("B","D");
        putData("B","G");
        System.out.println(tmpMap.toString());
        makeTree("A",1);

    }