List数据按照树状结构(tree)进行排序

一般应用我们都是把数据直接转成树状结构。这个可以通过sql实现，但是也有用到只按照树状结构排序的情况。（适用于网站栏目设置，并且可以排序这样的功能）

以下代码是整理自网上的，以供参考：

1、一个Bean，用于模仿我们平时接收数据的实体类

public class MyTestTree {
	private int id;

	private String name;

	private int parentId;
	
	private int no_order;

	private List childrens;

	public MyTestTree(int id, String name, int parentId,int no_order) {
		this.id = id;
		this.name = name;
		this.parentId = parentId;
		this.no_order = no_order;
	}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getParentId() {
		return parentId;
	}

	public void setParentId(int parentId) {
		this.parentId = parentId;
	}

	public List getChildrens() {
		return childrens;
	}

	public void setChildrens(List childrens) {
		this.childrens = childrens;
	}

	public int getNo_order() {
		return no_order;
	}

	public void setNo_order(int no_order) {
		this.no_order = no_order;
	}
}

2、使用测试数据进行排序

public class TestListTree {

	public static void main(String[] args) {
		// id,pid(父节点),name(节点名称),sequence(同级节点排序依据)
		MyTestTree tree1 = new MyTestTree(1, "顶层节点1", 0, 1);
		MyTestTree tree2 = new MyTestTree(2, "顶层节点2", 0, 2);
		MyTestTree tree3 = new MyTestTree(3, "顶层节点3", 0, 3);

		MyTestTree tree4 = new MyTestTree(4, "二级节点4", 1, 1);
		MyTestTree tree5 = new MyTestTree(5, "二级节点5", 2, 2);
		MyTestTree tree6 = new MyTestTree(6, "二级节点6", 3, 3);

		MyTestTree tree7 = new MyTestTree(7, "三级节点7", 4, 1);
		MyTestTree tree8 = new MyTestTree(8, "三级节点8", 4, 2);
		MyTestTree tree9 = new MyTestTree(9, "三级节点9", 5, 1);

		List list = new ArrayList();
		list.add(tree1);
		list.add(tree2);
		list.add(tree3);
		list.add(tree4);
		list.add(tree5);
		list.add(tree6);
		list.add(tree7);
		list.add(tree8);
		list.add(tree9);

		LinkedList result = new LinkedList();
		LinkedList f = toSort(list, result, 0);
		for (int i = 0; i < f.size(); i++) {
			System.out.print(f.get(i).getId() + ",");
			System.out.print(f.get(i).getName() + ",");
			System.out.print(f.get(i).getParentId() + ",");
			System.out.println(f.get(i).getNo_order());
		}
	}
	
	/**
	 * 
	 * @Description: 排序
	 * @param list
	 * @param result
	 * @param father
	 * @return
	 * LinkedList
	 */
	private static LinkedList toSort(List list,
			LinkedList result, int father) {
		List temp = new ArrayList();
		// 最高层,临时存放
		for (int i = 0; i < list.size(); i++) {
			if (list.get(i).getParentId() == father) {
				temp.add(list.get(i));
			}
		}

		if (temp.size() < 1) {
			return result;
		} else { 
			// 删除最高层
			for (int j = 0; j < list.size(); j++) {
				if (list.get(j).getParentId() == father) {
					list.remove(j);
				}
			}
			// 对最高层排序
			for (int i = 0; i < temp.size() - 1; i++) {
				for (int j = i + 1; j < temp.size(); j++) {
					if (temp.get(i).getNo_order() > temp.get(j).getNo_order()) {
						MyTestTree myTestTree = temp.get(i);
						temp.set(i, temp.get(j));
						temp.set(j, myTestTree);
					}
				}
			}
			// 递归
			for (int i = 0; i < temp.size(); i++) {
				result.add(temp.get(i));
				toSort(list, result, temp.get(i).getId());
			}
			return result;
		}

	}
}