[英]How to sort a map of type Map<String, List<String>> in Java
I'm trying to sort a map Map> which the map key set contain the order 1 2 3 4 ext ...我正在尝试对地图 Map> 进行排序,其中地图键集包含顺序 1 2 3 4 ext ...
The file which I'm retrieving data filter.properties 1=gwtCacheControlFilter:com.palmyra.arch.presentation.port.server.GWTCacheControlFilter:true:/*:null:presentation我正在检索数据的文件filter.properties 1=gwtCacheControlFilter:com.palmyra.arch.presentation.port.server.GWTCacheControlFilter:true::/*:null:presentation
public Map<String, List<String>> initiateMapOfFilters() throws IOException {
Map<String, List<String>> filterMap = new HashMap<>();
Properties properties = new Properties();
properties.load(FilterFileStream);
for (Entry<Object, Object> filterFromFile : properties.entrySet()) {
String filterValue = filterFromFile.getValue().toString();
String[] split = filterValue.split(":");
ArrayList<String> list = new ArrayList<>();
for (String s : split) {
list.add(s);
}
//-------sort the list with order
filterMap.put(split[filterNameIndex], list);
}
// Map<String, String> treeMap = new TreeMap<String, String>((Comparator<? super String>) filterMap); comment
return filterMap;
}
I want to return a map ordered by the key I tried:我想返回按我试过的键排序的地图:
Map<String, String> treeMap = new TreeMap<String, String>((Comparator<? super String>) filterMap);
Thank you for any suggestion.谢谢你的任何建议。
You have to use a comparator to make it work!您必须使用比较器才能使其工作! Like this :
像这样 :
Map<Integer,String> unsortedMap = new Hashmap<Integer,String>();
Map<Integer,String> treeMap = new TreeMap<Integer,String>(
new Comparator<Integer>() {
@Override
public int compare(Integer o1, Integer o2) {
return o2.compareTo(o1);//sort in descending order
}
});
Consider the below code.考虑下面的代码。 With java 8 you can use the Comparator.comparing method and get it done quite quickly.
使用 java 8,您可以使用 Comparator.comparing 方法并很快完成。
TreeMap<String, List<String>> treeMap = new TreeMap<>(Comparator.comparing(t -> Integer.valueOf(t)));
treeMap.put("5", Arrays.asList(new String[] {"data1", "data2", "data3"}));
treeMap.put("3", Arrays.asList(new String[] {"data4", "data5", "data6"}));
treeMap.put("1", Arrays.asList(new String[] {"data7", "data8", "data9"}));
treeMap.put("4", Arrays.asList(new String[] {"data10", "data11", "data12"}));
treeMap.
forEach((k,v) -> System.out.println(k + "=="+v));
Output is sorted on basis of keys:输出根据键排序:
1==[data7, data8, data9]
3==[data4, data5, data6]
4==[data10, data11, data12]
5==[data1, data2, data3]
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