In this tutorial, we will see “How to sort a Map by Key & Value in Java 8 using LinkedHashMap?”
Approach/Steps:
1. Create a Map object and add values to it. 2. Convert Map object into a Stream. 3. Sort it now. 4. Finally, either collect it with LinkedHashMap OR perform the forEachOrdered operation with LinkedHashMap.
Sort a Map in Java 8 with examples...!!! Share on X
Example 1. Sort Map by Key using LinkedHashMap with Collect
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.stream.Collectors;
public class Sort_Map_ByKey_With_Collect_Java8 {
public static void main(String[] argv) {
Map <String, Integer> unsortedMapObj = new HashMap <> ();
unsortedMapObj.put("Tom", 50);
unsortedMapObj.put("Brett", 45);
unsortedMapObj.put("Ashton", 9);
unsortedMapObj.put("Claire", 78);
unsortedMapObj.put("Daniella", 2);
System.out.println("Original Unsorted Map: \n" + unsortedMapObj);
Map <String, Integer> sortedMapObj = unsortedMapObj
.entrySet()
.stream()
.sorted(Map.Entry.comparingByKey())
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> oldValue, LinkedHashMap::new));
System.out.println("\nResulted Sorted Map by Key in ascending order: \n" + sortedMapObj);
}
}
Output:
Original Unsorted Map:
{Claire=78, Brett=45, Tom=50, Daniella=2, Ashton=9}
Resulted Sorted Map by Key in ascending order:
{Ashton=9, Brett=45, Claire=78, Daniella=2, Tom=50}
Example 2. Sort Map by Key using LinkedHashMap with ForEachOrdered
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
public class Sort_Map_ByKey_With_ForEachOrdered_Java8 {
public static void main(String[] args) {
Map <String, Integer> unsortedMapObj = new HashMap <> ();
unsortedMapObj.put("Tom", 50);
unsortedMapObj.put("Brett", 45);
unsortedMapObj.put("Ashton", 9);
unsortedMapObj.put("Claire", 78);
unsortedMapObj.put("Daniella", 2);
System.out.println("Original Unsorted Map: \n" + unsortedMapObj);
Map <String, Integer> sortedMapObj = new LinkedHashMap <> ();
unsortedMapObj.entrySet()
.stream()
.sorted(Map.Entry.comparingByKey())
.forEachOrdered(i -> sortedMapObj.put(i.getKey(), i.getValue()));
System.out.println("\nResulted Sorted Map by Key in ascending order: \n" + sortedMapObj);
}
}
Output:
Original Unsorted Map:
{Claire=78, Brett=45, Tom=50, Daniella=2, Ashton=9}
Resulted Sorted Map by Key in ascending order:
{Ashton=9, Brett=45, Claire=78, Daniella=2, Tom=50}
Example 3. Sort Map by Value using LinkedHashMap with Collect
import java.util.Comparator;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.stream.Collectors;
public class Sort_Map_ByValue_With_Collect_Java8 {
public static void main(String[] argv) {
Map <String, Integer> unsortedMapObj = new HashMap <> ();
unsortedMapObj.put("Tom", 50);
unsortedMapObj.put("Brett", 45);
unsortedMapObj.put("Ashton", 9);
unsortedMapObj.put("Claire", 78);
unsortedMapObj.put("Daniella", 2);
System.out.println("Original Unsorted Map: \n" + unsortedMapObj);
Map <String, Integer> sortedMapObj = unsortedMapObj.entrySet()
.stream()
.sorted(Map.Entry.comparingByValue(Comparator.naturalOrder()))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (oldValue, newValue) -> oldValue, LinkedHashMap::new));
System.out.println("\nResulted Sorted Map by value in ascending order: \n" + sortedMapObj);
}
}
Output:
Original Unsorted Map:
{Claire=78, Brett=45, Tom=50, Daniella=2, Ashton=9}
Resulted Sorted Map by value in ascending order:
{Daniella=2, Ashton=9, Brett=45, Tom=50, Claire=78}
Example 4. Sort Map by Value using LinkedHashMap with ForEachOrdered
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
public class Sort_Map_ByValue_With_ForEachOrdered_Java8 {
public static void main(String[] argv) {
Map <String, Integer> unsortedMapObj = new HashMap <> ();
unsortedMapObj.put("Tom", 50);
unsortedMapObj.put("Brett", 45);
unsortedMapObj.put("Ashton", 9);
unsortedMapObj.put("Claire", 78);
unsortedMapObj.put("Daniella", 2);
System.out.println("Original Unsorted Map: \n" + unsortedMapObj);
Map <String, Integer> sortedMapObj = new LinkedHashMap <> ();
unsortedMapObj.entrySet()
.stream()
.sorted(Map.Entry. <String, Integer> comparingByValue())
.forEachOrdered(x -> sortedMapObj.put(x.getKey(), x.getValue()));
System.out.println("\nResulted Sorted Map by value in ascending order: \n" + sortedMapObj);
}
}
Output:
Original Unsorted Map:
{Claire=78, Brett=45, Tom=50, Daniella=2, Ashton=9}
Resulted Sorted Map by value in ascending order:
{Daniella=2, Ashton=9, Brett=45, Tom=50, Claire=78}
Sort a Map in Java 8 with examples...!!! Share on X
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