如何对HashMap freemarker模板的值进行排序

Question

I have in java this HashMap:

HashMap<String, String> map = new HashMap<String, String>();

     map.put("k1",  "3");
     map.put("k2", "4");
     map.put("k3", "2");
     map.put("k4", "6");
     map.put("k5", "1");
     map.put("k6", "5");

I print with freemarker template in this mode:

<#list map?values as v>
${v} - 
</#list>

but it prints in this order:

2 - 6 - 1 - 5 - 3 - 4

I would like to print in this order:

1 - 2 - 3 - 4 - 5  -6

how can I sort values ​​with with freemarker template?

Answer 1

Try this:

<#list map?values?sort as v>
    ${v} - 
</#list>

Notice the use of the sort builtin for the sequence of values.

Answer 2

If you are displaying the values independent of the keys then you can take the values out of the map and construct a TreeSet from it. Then the values would be in order.

TreeSet ordered =  new TreeSet(map.values());

Then

 <#list ordered as v>
     ${v} - 
 </#list>

Answer 3

This behaviour is predictable as HashMaps are not ordered. As has been pointed out in the comments a SortedMap eg TreeMap will sort on the keys. So you're going to have to cut some code to sort this.

See Sort a Map<Key, Value> by values (Java)

Answer 4

HashMap is not ordered. You should use a TreeMap instead which implements a SortedMap :-

SortedMap<String, String> map = new TreeMap<String, String>();

Please note - Sorted Map provides a total ordering on its keys . You cannot have it sorted on the values. If you want to sort on values you can always do that by sorting on the Map.entrySet() using a Comparable .

Also take a look at this very similar question: TreeMap sort by value

Answer 5

如果需要以可预测的顺序迭代HashMap ，则可以使用具有可预测迭代顺序的LinkedHashMap ，它维护一个运行所有条目的双向链表。