Question

我想创建一个每一行包含如下数组的列表：

key1 ->value1
key2 ->value2
key3 ->value3

（键和值为字符串）
我怎么能这样做？

Answer 1

如果您的密钥必须是String，那么您希望使用Map而不是数组。你想要/需要一个List<Map<String, String>>。

以下是一个例子：

//declaring and initializing the list of maps
//line below works for Java 7
//List<Map<String, String>> listOfMaps = new ArrayList<>();
//if you want/need to use Java 6 then use the following
List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();

//declaring, initializing and filling a map
//line below works for Java 7
//Map<String, String> map1 = new HashMap<>();
//if you want/need to use Java 6 then use the following
Map<String, String> map1 = new HashMap<String, String>();
map1.put("name", "Luiggi");
map1.put("lastname", "Mendoza");
map1.put("maintag", "Java");

//declaring, initializing and filling another map
//line below works for Java 7
//Map<String, String> map2 = new HashMap<>();
//if you want/need to use Java 6 then use the following
Map<String, String> map2 = new HashMap<String, String>();
map2.put("name", "Foo");
map2.put("lastname", "Bar");
map2.put("maintag", "Scala"); //I have nothing against scala

//add maps into the list
listOfMaps.add(map1);
listOfMaps.add(map2);

//Show contents of the list and map
System.out.println(listOfMaps);

//Traverse each element of the List to access key and value
int index = 0;
//it is better to use Iterator or enhanced for each than using List#get(index)
for (Map<String, String> map : listOfMaps) {
    System.out.println("Printing element " + index++);
    for(Map.Entry<String, String> entry : map.entrySet()) {
        System.out.println(entry.getKey() + ": " + entry.getValue());
    }
    System.out.println("--------------------------");
}

Answer 2

您可以使用

ArrayList<Map<String, String>>()

这将具有以下结构

列表索引0：Key1 - ＆gt;值1，Key2 - ＆gt;价值2
列表索引1：Key3 - ＆gt;价值3

所以要设置一个键值对：

List<Map<String, String>> list = new ArrayList<Map<String, String>>();
Map<String, String> map = new HashMap<String, String>();
map.put(key, value);
map.put(key1, value1);
list.add(map);

所以要从列表的第一个索引中的键中获取值：

String value = list.get(0).get(key)

Answer 3

Map<String, String> map = new HashMap<String, String>();
map.put("key1", "1");
map.put("key2", "2");

Map<String, String> anotherMap = new HashMap<String, String>();
anotherMap .put("key3", "3");
anotherMap .put("key4", "4");

List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();
listOfMaps.add(map);
listOfMaps.add(anotherMap);

为什么需要此列表？你需要做什么？或者这只是一个练习？

创建一个数组列表

3 个答案: