java ordering a map code example

Example: Java sort Map by values

//----------------------------------------------------------------------
// in ascending order:
Map<String, Integer> unSortedMap = getUnSortedMap();
         
System.out.println("Unsorted Map : " + unSortedMap);
 
//LinkedHashMap preserve the ordering of elements in which they are inserted
LinkedHashMap<String, Integer> sortedMap = new LinkedHashMap<>();
 
unSortedMap.entrySet()
    .stream()
    .sorted(Map.Entry.comparingByValue())
    .forEachOrdered(x -> sortedMap.put(x.getKey(), x.getValue()));
 
System.out.println("Sorted Map   : " + sortedMap);
 
Output:
 
Unsorted Map : {alex=1, charles=4, david=2, brian=5, elle=3}
Sorted Map   : {alex=1, david=2, elle=3, charles=4, brian=5}


//----------------------------------------------------------------------
// in descending order:
Map<String, Integer> unSortedMap = getUnSortedMap();
         
System.out.println("Unsorted Map : " + unSortedMap);
 
//LinkedHashMap preserve the ordering of elements in which they are inserted
LinkedHashMap<String, Integer> reverseSortedMap = new LinkedHashMap<>();
 
//Use Comparator.reverseOrder() for reverse ordering
unSortedMap.entrySet()
    .stream()
    .sorted(Map.Entry.comparingByValue(Comparator.reverseOrder())) 
    .forEachOrdered(x -> reverseSortedMap.put(x.getKey(), x.getValue()));
 
System.out.println("Reverse Sorted Map   : " + reverseSortedMap);
 
Output:
 
Unsorted Map        : {alex=1, charles=4, david=2, brian=5, elle=3}
Reverse Sorted Map  : {brian=5, charles=4, elle=3, david=2, alex=1}