Java 树形结构生成序号实现

public class TreeVO {

    private String sqNum;

    private Long id;

    private Long parentId;

    private List childList;
}

用上面树形结构生成下面这样的序号

1-1
1-1.1
1-1.2
1-2
1-2.1
1-2.1

public class TreeSequenceNumber {

    public static void main(String[] args) {
        TreeSequenceNumber treeSequenceNumber = new TreeSequenceNumber();
        treeSequenceNumber.createSeqNum();
    }


    void createSeqNum() {
        //组装数据
        List treeList = createData();

        //根节点生成序号
        for (int i = 0; i < treeList.size(); i++) {
            TreeVO treeVO = treeList.get(i);
            String parentSeqNum = i + 1 + "";
            treeVO.setSqNum(parentSeqNum);
            recursiveLoopCreateSeqNum(treeVO.getChildList(), parentSeqNum);
        }

        //打印结果
        System.out.println(JSON.toJSONString(treeList));
    }


    void recursiveLoopCreateSeqNum(List treeList, String parentSeqNum) {
        if (null == treeList || treeList.size() < 1) {
            return;
        }
        for (int i = 0; i < treeList.size(); i++) {
            TreeVO treeVO = treeList.get(i);
            String childSeqNum = parentSeqNum + "-" + (i + 1);
            treeVO.setSqNum(childSeqNum);
            recursiveLoopCreateSeqNum(treeVO.getChildList(), childSeqNum);
        }
    }


    
    List createData() {
        //树形结构数据列表
        List treeVOList = new ArrayList<>();

        //造数据
        TreeVO treeVO1 = new TreeVO();
        treeVO1.setParentId(5L);
        treeVO1.setId(1L);

        TreeVO treeVO2 = new TreeVO();
        treeVO2.setParentId(5L);
        treeVO2.setId(2L);

        TreeVO treeVO3 = new TreeVO();
        treeVO3.setParentId(6L);
        treeVO3.setId(3L);

        TreeVO treeVO4 = new TreeVO();
        treeVO3.setParentId(6L);
        treeVO4.setId(4L);


        List treeVO5ChildList = new ArrayList<>();
        treeVO5ChildList.add(treeVO1);
        treeVO5ChildList.add(treeVO2);

        TreeVO treeVO5 = new TreeVO();
        treeVO5.setId(5L);
        treeVO5.setParentId(0L);
        treeVO5.setChildList(treeVO5ChildList);

        List treeVO6ChildList = new ArrayList<>();
        treeVO6ChildList.add(treeVO3);
        treeVO6ChildList.add(treeVO4);

        TreeVO treeVO6 = new TreeVO();
        treeVO6.setId(6L);
        treeVO6.setParentId(0L);
        treeVO6.setChildList(treeVO6ChildList);

        treeVOList.add(treeVO5);
        treeVOList.add(treeVO6);

        return treeVOList;
    }

}

最终结果：

[{
	"childList": [{
		"id": 1,
		"parentId": 5,
		"sqNum": "1-1"
	}, {
		"id": 2,
		"parentId": 5,
		"sqNum": "1-2"
	}],
	"id": 5,
	"parentId": 0,
	"sqNum": "1"
}, {
	"childList": [{
		"id": 3,
		"parentId": 6,
		"sqNum": "2-1"
	}, {
		"id": 4,
		"sqNum": "2-2"
	}],
	"id": 6,
	"parentId": 0,
	"sqNum": "2"
}]