Question

我有一个两个数组列表，在单个索引处有多个值。我正在添加如下的值：

ArrayList<String> list1 = new ArrayList<String>();
list1.addAll(Arrays.asList("iFRa1wVJ","Breakfast","7:00am","8:30am"));
list1.addAll(Arrays.asList("JyvmCZhw","Lunch","1:00pm","3:00pm"));
list1.addAll(Arrays.asList("HR6ovPjE","Dinner","7:30pm","9:30pm"));


ArrayList<String> list2 = new ArrayList<String>();
list2.addAll(Arrays.asList("iFRa1wVJ","Breakfast1","9:00am","10:30am"));
list2.addAll(Arrays.asList("JyvmCZhw","Lunch","2:00pm","3:00pm"));
list2.addAll(Arrays.asList("HR6ovPjE","Dinner","8:30pm","9:30pm"));

预期结果如下：

   iFRa1wVJ,Breakfast,7:00am,8:30am --> Breakfast1 is overwriiten as Breakfast from list1
   JyvmCZhw,Lunch,1:00pm,3:00pm --> 2:00pm is overwriiten as 1:00pm from list1
   HR6ovPjE,Dinner,7:30pm,9:30pm --> 8:30pm is overwriiten as 7:30pm from list1

我需要比较每个索引的值，并使用第一个列表的值更新第二个列表。如何比较每个索引中的列表。任何帮助将不胜感激。感谢。

Answer 1

听起来好像最好使用Map或Set代替List。例如：

class Meal {
    //You may want to store times in a different format, i.e. a long in millisecond
    private final String name, startTime, endTime;

    Meal(String name, String startTime, String endTime) {
        this.name = name;
        this.startTime = startTime;
        this.endTime = endTime;
    }

    //getName(), getStartTime(), getEndTime()...

}

在你的地图上......

final Map<String, Meal> map = new HashMap<>();
map.put("iFRa1wVJ", new Meal("Breakfast","7:00am","8:30am"));
map.put("iFRa1wVJ", new Meal("Breakfast","9:00am","10:30am"));

第二个“早餐”将取代第一个“早餐”，因为它们共享相同的密钥。

Answer 2

您希望在每个索引处有两个具有多个值的数组列表，但在原始代码中ArrayList<String>只是一个在每个索引处都有一个String对象的数组。所以我更改了数据结构以保存String的列表。如果您真正想要做的就是使用相应索引list1的值更新每个索引，您只需更新索引处的所有内容。

ArrayList<List<String>> list1 = new ArrayList<List<String>>();
list1.add(Arrays.asList("iFRa1wVJ", "Breakfast", "7:00am", "8:30am"));
list1.add(Arrays.asList("JyvmCZhw", "Lunch", "1:00pm", "3:00pm"));
list1.add(Arrays.asList("HR6ovPjE", "Dinner", "7:30pm", "9:30pm"));

ArrayList<List<String>> list2 = new ArrayList<List<String>>();
list2.add(Arrays.asList("iFRa1wVJ", "Breakfast1", "9:00am", "10:30am"));
list2.add(Arrays.asList("JyvmCZhw", "Lunch", "2:00pm", "4:00pm"));
list2.add(Arrays.asList("HR6ovPjE", "Dinner", "8:30pm", "9:30pm"));

for (int i = 0; i < list1.size(); i++) {
    list2.set(i, list1.get(i));
}

System.out.println(list1);

比较和更新两个arraylist java android

2 个答案: