Long time no new post here. Kind of busy this lately and my writing mood was gone. Anyway, today I’m trying to share something related to basic Java programming.
I experienced difficulty to get a Map or HashMap to be sorted. And here I try to share how I handle it.
Sample of Map:
Map sampleMap = new HashMap(); sampleMap.put("key1", "value1"); sampleMap.put("key2", "value2"); sampleMap.put("key3", "value3"); sampleMap.put("key4", "value3");
If you see, I put the map in ascending order. But later when you try to retrieve the value, you will find the Map is not in order. From what I understand, Map will store the object ANYWHERE inside the memory. Below is my simple sample how to retrieve the value in order.
I store the key inside a List, and sort the list of key:
List sortedKeys = new ArrayList(sampleMap.keySet()); Collections.sort(sortedKeys);
Now you already have a List contains key of the map that has been sorted. The rest, use the sortedKeys to retrieve the object from the sampleMap.
Hope this can be useful.