I need your assiatance please:
I have a map :
Map<String, Object[]> data = new HashMap<String, Object[]>();
The Object[] array is built out of triples: [String, String, Integer]
Later on, I am going to read the object[] array values, but I should print them sorted according to the integer value.
How can I do this in the best way?
Thank you!
One way is with a stream:
data.values().stream()
.sorted(Comparator.comparing(a -> (Integer)a[2]))
.forEachOrdered(a -> System.out.println(Arrays.toString(a)));
First you have to extract the values from the map. Then you can use a sort method implementation from native java, with your custom comparator.
Map<String, Object[]> data = new HashMap<String, Object[]>();
List<Object[]> values = new ArrayList<Object[]>();
values.addAll(data.values());
Collections.sort(values, new Comparator<Object[]>()
{
@Override
public int compare(Object[] o1, Object[] o2)
{
// TODO implement me
// o1 less than o2 ? return -1
// o1 greater than o2 ? return 1
// o1 equals o2 ? return 0
}
});
In this example you only need to implement the compare method. From the docs:
Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.
You can also take a look at: Sort ArrayList of custom Objects by property
Use Java 8 to sort the values.
final Map<String, Object[]> data = new HashMap<>();
data.put("foo", new Object[]{"A", "B", 1});
data.put("bar", new Object[]{"C", "D", 2});
data.put("baz", new Object[]{"E", "F", 3});
final Comparator<Object[]> comparator = (oa1, oa2) ->
((Integer) oa1[2]).compareTo((Integer) oa2[2]);
List<Object[]> sorted =
data.values().stream().sorted(comparator).collect(Collectors.toList());
Set<Object[]>and from this set, you can sort according to the Integer value.new HashMap<String, Object[]>()? Don't you use Java 7+? With streams, it will be much easier to do the sorting. Only if it were not a Object[] but a complex object.