根据list集合类的某个字段组合数据

最新推荐文章于 2024-02-29 09:30:25 发布

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最新推荐文章于 2024-02-29 09:30:25 发布

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分类专栏：集合

本文链接：https://blog.youkuaiyun.com/weixin_42274773/article/details/103970099

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这篇博客介绍如何利用Java对List集合中的对象，依据某个特定字段进行数据的组合与分组，以实现更高效的数据处理。

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代码

  public void bt3(View view) {
        Map<String, Bean> map = new HashMap<>();//分类 如下 应分三个集合
        map.put("1", new Bean("1", "2", "3", "4"));
        map.put("2", new Bean("1", "2", "3", "5"));
        map.put("3", new Bean("1", "2", "4", "6"));
        map.put("4", new Bean("1", "3", "7", "9"));
        map.put("5", new Bean("2", "2", "3", "4"));
        map.put("6", new Bean("2", "2", "7", "9"));
        map.put("7", new Bean("2", "3", "3", "8"));
        map.put("8", new Bean("3", "3", "3", "8"));
        LogUtils.E(map.toString());
        //把map转换成list
        List<Bean> beans = new ArrayList<>();
        for (Bean b : map.values()) {
            beans.add(b);
        }
        //string字段相同存入map
        Map<String, String> mapstring = new HashMap<>();
        for (Bean b : beans) {
            mapstring.put(b.getString(), b.getString());
        }
        LogUtils.E(mapstring.toString());
        //组合分类数据
        List<List<Bean>> listList = new ArrayList<>();
        for (Map.Entry<String, String> entry : mapstring.entrySet()) {
            List<Bean> lisdan=new ArrayList<>();
            for (Bean b : map.values()) {
                if (entry.getKey().equals(b.getString())) {
                    lisdan.add(b);
                }
            }
            LogUtils.E(lisdan.toString());
            listList.add(lisdan);
        }
        LogUtils.E(listList.toString());
}
/*
*类
**/
  class Bean {
        private String string;
        private String title;
        private String content;
        private String icon;
//get，set，构造器
}

分类结果

2020-01-14 11:17:12.217 12701-12701/com.ms.liu E/项目: [ main: RxOrBusActivity.java:95 bt3 ] - [Bean{string='1', title='2', content='3', icon='4'}, Bean{string='1', title='2', content='3', icon='5'}, Bean{string='1', title='2', content='4', icon='6'}, Bean{string='1', title='3', content='7', icon='9'}]
2020-01-14 11:17:12.218 12701-12701/com.ms.liu E/项目: [ main: RxOrBusActivity.java:95 bt3 ] - [Bean{string='2', title='2', content='3', icon='4'}, Bean{string='2', title='2', content='7', icon='9'}, Bean{string='2', title='3', content='3', icon='8'}]
2020-01-14 11:17:12.219 12701-12701/com.ms.liu E/项目: [ main: RxOrBusActivity.java:95 bt3 ] - [Bean{string='3', title='3', content='3', icon='8'}]
2020-01-14 11:17:12.221 12701-12701/com.ms.liu E/项目: [ main: RxOrBusActivity.java:98 bt3 ] - [[Bean{string='1', title='2', content='3', icon='4'}, Bean{string='1', title='2', content='3', icon='5'}, Bean{string='1', title='2', content='4', icon='6'}, Bean{string='1', title='3', content='7', icon='9'}], [Bean{string='2', title='2', content='3', icon='4'}, Bean{string='2', title='2', content='7', icon='9'}, Bean{string='2', title='3', content='3', icon='8'}], [Bean{string='3', title='3', content='3', icon='8'}]]