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假想面试题：现在有一串字符串2, 2, 3……，其中字符串中的数字类似于Word文档中的标题级别，最终效果是让它们按照Word文档导航窗格中的标题级别格式进行展示

目录

    • 一、问题
    • 二、答案
      • 1、依赖
      • 2、代码
      • 3、结果
      • 4、思路分析
    • 三、拓展
      • 1、反向思维
      • 2、引用数据类型
    • 四、实战
      • 1、背景
      • 2、实战模拟
        • 2.1、代码
        • 2.2、结果

一、问题

现在有一串字符串2, 2, 3, 4, 4, 3, 4, 4, 5, 5, 5, 5, 5, 3, 4, 4, 4, 4, 4, 3, 4, 4，其中字符串中的数字类似于Word文档中的标题级别，最终效果是让它们按照Word文档导航窗格中的标题级别格式进行展示，具体展示效果如下：

二、答案

1、依赖

<dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.78</version>
</dependency>

2、代码

public class Test {public static void main(String[] args) {// 数据准备开始String numString = "2, 2, 3, 4, 4, 3, 4, 4, 5, 5, 5, 5, 5, 3, 4, 4, 4, 4, 4, 3, 4, 4";String[] split = numString.split(", ");List<Integer> list = new ArrayList<>();for (String s : split) {list.add(Integer.valueOf(s));}// 数据准备结束// 已处理对象集合List<Number> numberList = new ArrayList<>();// 最高级对象Number result = new Number();result.setChilds(new ArrayList<>());for (Integer num : list) {// 当前对象Number entity = new Number();entity.setNum(num);entity.setChilds(new ArrayList<>());// 获取父级对象Number parent = getParent(numberList, num);if (parent == null) {result.getChilds().add(entity);} else {parent.getChilds().add(entity);}// 放入集合numberList.add(entity);}// 数据打印for (Number child : result.getChilds()) {printNumber(child, "");}}/*** 数据打印** @param number 对象* @param prefix 前缀**/private static void printNumber(Number number, String prefix) {System.out.println(prefix + number.getNum());List<Number> childs = number.getChilds();if (childs == null || childs.size() == 0) {return;}for (Number child : childs) {printNumber(child, prefix + "    ");}}/*** 获取父类（采用反向思维查找）** @param numberList 对象集合* @param num        数字* @return 对象**/private static Number getParent(List<Number> numberList, Integer num) {if (numberList.size() == 0) {return null;}for (int i = numberList.size() - 1; i >= 0; i--) {Number number = numberList.get(i);if (number.getNum() < num) {return number;}}return null;}
}/*** 数字类（存储数字和子级对象）*/
class Number {private Integer num;private List<Number> childs;public Integer getNum() {return num;}public void setNum(Integer num) {this.num = num;}public List<Number> getChilds() {return childs;}public void setChilds(List<Number> childs) {this.childs = childs;}
}

3、结果

2
234434455555344444344

4、思路分析

首先创建一个Number类，然后类里面的childs属性是List<Number>，这是大多数人都可以想到的事情，问题关键在于如何让对应的序号放到对应的childs属性里面，那也就是找到当前节点的父节点，按照上面的逻辑，子节点的序号肯定大于父节点的序号，并且父节点顺序肯定在子节点的前面，并且具体子节点最近，因此我就把已经处理过的节点存储在numberList集合里面，然后采用反向思维的方式查找具体当前节点最近的父级节点

当然，如果子级节点没有父级节点，那么它就是最高级节点

三、拓展

1、反向思维

对于上面的问题，如果从正方向出发，其实很难有什么好的思路来进行实现，但是反向思维可以很好的解决该问题，所以以后遇到问题的时候，可以从反向出发来解决问题

2、引用数据类型

我把当前节点都是放在父节点的childs属性里面，我获取最终结果的时候只需要找到顶级节点就可以了，这其实就是引用数据类型起到的作用

四、实战

1、背景

公司有一个文档导入的项目，可以将docx文档进行导入，然后在页面上进行展示，在处理标题过程中，我们可以从上到下获取到所有的目录html，但是返回给前端的时候需要以目录树的方式返回，因此把这种实际情况进行抽象，其实就是上面的例子，公司项目中文档导入成功的截图如下：

2、实战模拟

2.1、代码

public class Test {public static void main(String[] args) {// 原始数据String jsonStr = "[\"<H2 id =\\\"h_f5ec3fd69a4d497ca4b33a10b3d71aa9\\\" name = \\\"h_f5ec3fd69a4d497ca4b33a10b3d71aa9\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:黑体;\\\"><span style=\\\"line-height:28.6pt;\\\">开发准备</span></H2>\",\"<H2 id =\\\"h_11533fd60df540dcb50e792873665d59\\\" name = \\\"h_11533fd60df540dcb50e792873665d59\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:黑体;\\\"><span style=\\\"line-height:28.6pt;\\\">功能说明</span></H2>\",\"<H3 id =\\\"h_e4569a42140041c98ae045603dbe103a\\\" name = \\\"h_e4569a42140041c98ae045603dbe103a\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:楷体;\\\"><span style=\\\"line-height:28.6pt;\\\">审批方案</span></H3>\",\"<H4 id =\\\"h_c6764240e50746f2bf08b93b36e868c4\\\" name = \\\"h_c6764240e50746f2bf08b93b36e868c4\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">配置文件</span></H4>\",\"<H4 id =\\\"h_df412c661a324d3d89e73e6e2144cfee\\\" name = \\\"h_df412c661a324d3d89e73e6e2144cfee\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">属性说明</span></H4>\",\"<H3 id =\\\"h_0bba1e95aa864e2b964254e5a4b13eae\\\" name = \\\"h_0bba1e95aa864e2b964254e5a4b13eae\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:楷体;\\\"><span style=\\\"line-height:28.6pt;\\\">集成接口</span></H3>\",\"<H4 id =\\\"h_f4d7e2cc579746b2b4e5476ed883e15d\\\" name = \\\"h_f4d7e2cc579746b2b4e5476ed883e15d\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">入口参数</span></H4>\",\"<H4 id =\\\"h_03fcedbe1dae4788b499dae77d05dc41\\\" name = \\\"h_03fcedbe1dae4788b499dae77d05dc41\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">相关接口</span></H4>\",\"<H5 id =\\\"h_778cdce51d214dde967f868780d0eab8\\\" name = \\\"h_778cdce51d214dde967f868780d0eab8\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">送审</span></H5>\",\"<H5 id =\\\"h_d0daa8157cd24b39a9d20b6165d2f2ec\\\" name = \\\"h_d0daa8157cd24b39a9d20b6165d2f2ec\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">同意</span></H5>\",\"<H5 id =\\\"h_40ba3e6901c8478399ffe3d4350932dc\\\" name = \\\"h_40ba3e6901c8478399ffe3d4350932dc\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">拟同意</span></H5>\",\"<H5 id =\\\"h_a4ae1d569ef94b92a57bd217ddab70d2\\\" name = \\\"h_a4ae1d569ef94b92a57bd217ddab70d2\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">不同意</span></H5>\",\"<H5 id =\\\"h_2abf049d3ba543638097170dbde425ba\\\" name = \\\"h_2abf049d3ba543638097170dbde425ba\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">收回</span></H5>\",\"<H3 id =\\\"h_a484ff6248dc4b3486f5716ed5116b82\\\" name = \\\"h_a484ff6248dc4b3486f5716ed5116b82\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:楷体;\\\"><span style=\\\"line-height:28.6pt;\\\">应用案例</span></H3>\",\"<H4 id =\\\"h_6fbc18ae698c43508bfe0894ec441b8f\\\" name = \\\"h_6fbc18ae698c43508bfe0894ec441b8f\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">送审</span></H4>\",\"<H4 id =\\\"h_81e4902a4db746df87823635a588dcc1\\\" name = \\\"h_81e4902a4db746df87823635a588dcc1\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">同意</span></H4>\",\"<H4 id =\\\"h_adccf8ec1c9f41fd9f2e8a3c4dfa4958\\\" name = \\\"h_adccf8ec1c9f41fd9f2e8a3c4dfa4958\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">拟同意</span></H4>\",\"<H4 id =\\\"h_04c7c25c2edb4a5ca083cf50099d5768\\\" name = \\\"h_04c7c25c2edb4a5ca083cf50099d5768\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">不同意</span></H4>\",\"<H4 id =\\\"h_1273a45625e64b07b680ae66ca7160fc\\\" name = \\\"h_1273a45625e64b07b680ae66ca7160fc\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">收回</span></H4>\",\"<H3 id =\\\"h_b7455f2532254807bbdd36a08b3e587a\\\" name = \\\"h_b7455f2532254807bbdd36a08b3e587a\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:楷体;\\\"><span style=\\\"line-height:28.6pt;\\\">数据展示</span><span style=\\\"line-height:28.6pt;\\\">的接口</span></H3>\",\"<H4 id =\\\"h_4961ecfa9f7a4a95b6d6abf8f0d3a62c\\\" name = \\\"h_4961ecfa9f7a4a95b6d6abf8f0d3a62c\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">待提交</span></H4>\",\"<H4 id =\\\"h_9f16c84cc0e1451182b1487237906282\\\" name = \\\"h_9f16c84cc0e1451182b1487237906282\\\" style=\\\"mso-line-height-rule:exactly;line-height:28.6pt;font-size:21px;font-family:仿宋;\\\"><span style=\\\"line-height:28.6pt;\\\">已提交</span></H4>\"]";// 数据转换List<String> list = JSONObject.parseArray(jsonStr, String.class);// 存储最高级节点的集合List<Catalog> resultList = new ArrayList<>();// 存放已处理节点集合List<Catalog> catalogList = new ArrayList<>();for (String html : list) {// 获取id，用作前端锚点跳转String id = getId(html);// 获取目录名称String caption = getCaption(html);// 获取目录序号Integer num = getNum(html);// 创建当前对象Catalog entity = new Catalog();entity.setId(id);entity.setCaption(caption);entity.setNum(num);// 获取父级对象Catalog parent = getParent(catalogList, num);if (parent == null) {// 最高等级数据插入resultList.add(entity);} else {// 判断父级childs属性是否有值List<Catalog> childs = parent.getChilds();if (childs == null) {parent.setChilds(new ArrayList<>());}// 数据插入parent.getChilds().add(entity);}// 放入集合catalogList.add(entity);}// 打印目录树System.out.println(JSONObject.toJSONString(resultList));}/*** 获取父级节点对象** @param catalogList 已处理节点集合* @param num         目录序号* @return 父级节点对象*/private static Catalog getParent(List<Catalog> catalogList, Integer num) {if (catalogList.size() == 0) {return null;}for (int i = catalogList.size() - 1; i >= 0; i--) {Catalog catalog = catalogList.get(i);if (catalog.getNum() < num) {return catalog;}}return null;}/*** 获取id，用作前端锚点跳转** @param html 目录Html* @return id值*/private static String getId(String html) {// ?<=和?=的使用，可以看博客： pattern = "(?<=id =\").*?(?=\")";Matcher matcher = Patternpile(pattern, Pattern.CASE_INSENSITIVE).matcher(html);while (matcher.find()) {String id = matcher.group();return id;}return null;}/*** 获取目录标题** @param html 目录Html* @return 目录标题*/private static String getCaption(String html) {if (html != null) {return html.replaceAll("<p.*?>|</p>|<span.*?>|<span>|</span>|<H[1-9].*?>|</H[1-9]>", "");}return null;}/*** 获取目录序号** @param html 目录Html* @return 目录Html*/private static Integer getNum(String html) {String pattern = "(?<=<H).*?(?= id)";Matcher matcher = Patternpile(pattern, Pattern.CASE_INSENSITIVE).matcher(html);while (matcher.find()) {String group = matcher.group();Integer num = Integer.valueOf(group);return num;}return null;}
}/*** 目录*/
class Catalog {// idprivate String id;// 标题private String caption;// 序号private Integer num;private List<Catalog> childs;public Integer getNum() {return num;}public void setNum(Integer num) {this.num = num;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getCaption() {return caption;}public void setCaption(String caption) {this.caption = caption;}public List<Catalog> getChilds() {return childs;}public void setChilds(List<Catalog> childs) {this.childs = childs;}
}

2.2、结果

建议数据格式化之后再看，格式化网站：/

[{"caption":"开发准备","id":"h_f5ec3fd69a4d497ca4b33a10b3d71aa9","num":2},{"caption":"功能说明","childs":[{"caption":"审批方案","childs":[{"caption":"配置文件","id":"h_c6764240e50746f2bf08b93b36e868c4","num":4},{"caption":"属性说明","id":"h_df412c661a324d3d89e73e6e2144cfee","num":4}],"id":"h_e4569a42140041c98ae045603dbe103a","num":3},{"caption":"集成接口","childs":[{"caption":"入口参数","id":"h_f4d7e2cc579746b2b4e5476ed883e15d","num":4},{"caption":"相关接口","childs":[{"caption":"送审","id":"h_778cdce51d214dde967f868780d0eab8","num":5},{"caption":"同意","id":"h_d0daa8157cd24b39a9d20b6165d2f2ec","num":5},{"caption":"拟同意","id":"h_40ba3e6901c8478399ffe3d4350932dc","num":5},{"caption":"不同意","id":"h_a4ae1d569ef94b92a57bd217ddab70d2","num":5},{"caption":"收回","id":"h_2abf049d3ba543638097170dbde425ba","num":5}],"id":"h_03fcedbe1dae4788b499dae77d05dc41","num":4}],"id":"h_0bba1e95aa864e2b964254e5a4b13eae","num":3},{"caption":"应用案例","childs":[{"caption":"送审","id":"h_6fbc18ae698c43508bfe0894ec441b8f","num":4},{"caption":"同意","id":"h_81e4902a4db746df87823635a588dcc1","num":4},{"caption":"拟同意","id":"h_adccf8ec1c9f41fd9f2e8a3c4dfa4958","num":4},{"caption":"不同意","id":"h_04c7c25c2edb4a5ca083cf50099d5768","num":4},{"caption":"收回","id":"h_1273a45625e64b07b680ae66ca7160fc","num":4}],"id":"h_a484ff6248dc4b3486f5716ed5116b82","num":3},{"caption":"数据展示的接口","childs":[{"caption":"待提交","id":"h_4961ecfa9f7a4a95b6d6abf8f0d3a62c","num":4},{"caption":"已提交","id":"h_9f16c84cc0e1451182b1487237906282","num":4}],"id":"h_b7455f2532254807bbdd36a08b3e587a","num":3}],"id":"h_11533fd60df540dcb50e792873665d59","num":2}]

本文标签： 假想面试题现在有一串字符串2 2 3，其中字符串中的数字类似于Word文档中的标题级别，最终效果是让它们按照Word文档导航窗格中的标题级别格式进行展示

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