DEMO_01：List数据存储，回调函数，集合转字符串，元素去重

/**
 * 考核点：List数据存储，回调函数，集合转字符串，元素去重
 * <p>
 * 题目：
 * 1. 构建属性结构List<DemoNode> data,根据本包的data.png中数据结构图将数据存入data中(字就是nodeName)
 * 2. 将树形结构List<DemoNode>里面的元素全部遍历出来存放到List<String> list中，输出结果转换成字符串：粉粉碎机被粉碎机粉碎了怎么办
 * 3. 将list里元素去重后存放到List<String> result，输出结果转换成字符串：粉碎机被了怎么办
 */
public class Main01 {

    public static void main(String[] args) {

        // 树型数据存放
        List<DemoNode> data = new ArrayList<>();
        // 构建元素
        DemoNode demoNode = generateNodeTree();
        data.add(demoNode);

        // 遍历数据存放
        List<String> eleList = new ArrayList<>();
        getAllEle(eleList, data);

        System.out.println(String.join("", eleList));     // 粉粉碎机被粉碎机粉碎了怎么办

        // 去重后元素存放
        // method1: 使用set无法保证能按List顺序排序
        Set<String> set = new HashSet<>(eleList);
        List<String> result1 = new ArrayList<>(set);
        System.out.println(String.join("", result1)); // 了么粉被碎怎机办

        // method2: 使用List.contains方法判断重存放
        List<String> result2 = new ArrayList<>();
        for (String one : eleList) {
            if (!result2.contains(one)) {
                result2.add(one);
            }
        }
        System.out.println(String.join("", result2)); // 粉碎机被了怎么办
    }

    /**
     * 遍历树形结构（按层级从小到大）
     *
     * @param eleList  存放节点名称元素集合
     * @param nodeList 要遍历的元素集合
     */
    static void getAllEle(List<String> eleList, List<DemoNode> nodeList) {
        List<DemoNode> childList = new ArrayList<>();
        for (DemoNode one : nodeList) {
            eleList.add(one.getNodeName());
            if (one.getChild() != null && one.getChild().size() > 0) {
                childList.addAll(one.getChild());
            }
        }
        // 下一级有子节点，开始下一级遍历
        if (childList != null && childList.size() > 0) {
            getAllEle(eleList, childList);
        }
    }

    /**
     * 构建图片属性结构
     *
     * @return
     */
    private static DemoNode generateNodeTree() {
        /** 构造第三层元素并归属 **/
        DemoNode node31 = new DemoNode("被");
        List<DemoNode> node31Childs = addChildNodeList(new DemoNode("了"), new DemoNode("怎"));
        node31.setChild(node31Childs);

        DemoNode node33 = new DemoNode("碎");
        List<DemoNode> node33Childs = addChildNodeList(new DemoNode("么"), new DemoNode("办"));
        node33.setChild(node33Childs);

        /** 构造第二层元素并归属 **/
        DemoNode node21 = new DemoNode("粉");
        List<DemoNode> node21Childs = addChildNodeList(node31, new DemoNode("粉"));
        node21.setChild(node21Childs);

        DemoNode node22 = new DemoNode("碎");
        List<DemoNode> node22Childs = addChildNodeList(node33, new DemoNode("机"));
        node22.setChild(node22Childs);

        DemoNode node23 = new DemoNode("机");
        List<DemoNode> node23Childs = addChildNodeList(new DemoNode("粉"), new DemoNode("碎"));
        node23.setChild(node23Childs);

        /** 构造第一层元素并归属 **/
        DemoNode nodeRoot = new DemoNode("粉");
        List<DemoNode> nodeRootChilds = addChildNodeList(node21, node22, node23);
        nodeRoot.setChild(nodeRootChilds);

        return nodeRoot;
    }

    /**
     * 组装子节点
     *
     * @param childNodes
     * @return
     */
    private static List<DemoNode> addChildNodeList(DemoNode... childNodes) {
        List<DemoNode> list = new ArrayList<>();
        for (DemoNode one : childNodes) {
            list.add(one);
        }
        return list;
    }

}

/**
 * 节点数据
 */
public class DemoNode {

    private String NodeName; //节点名称
    private List<DemoNode> child; //子节点

    public String getNodeName() {
        return NodeName;
    }

    public void setNodeName(String nodeName) {
        NodeName = nodeName;
    }

    public List<DemoNode> getChild() {
        return child;
    }

    public void setChild(List<DemoNode> child) {
        this.child = child;
    }

    public DemoNode(String nodeName) {
        NodeName = nodeName;
    }

    public DemoNode() {
    }
}