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Java Collection, TreeMap Exercises: Get the portion of a map whose keys range from a given key to another key

Java Collection, TreeMap Exercises: Exercise-21 with Solution

Write a Java program to get the portion of a map whose keys range from a given key (inclusive), to another key (exclusive).

Sample Solution:-

Java Code:

import java.util.*;
import java.util.Map.Entry;  
public class Example21 {  
          public static void main(String args[]) {

  // Declare tree maps
  TreeMap < Integer, String > tree_map = new TreeMap < Integer, String > ();
  SortedMap < Integer, String > sub_tree_map = new TreeMap < Integer, String > ();

  // Put elements to the map 
  tree_map.put(10, "Red");
  tree_map.put(20, "Green");
  tree_map.put(30, "Black");
  tree_map.put(40, "White");
  tree_map.put(50, "Pink");
  System.out.println("Orginal TreeMap content: " + tree_map);
  sub_tree_map = tree_map.subMap(20, 40);
  System.out.println("Sub map key-values: " + sub_tree_map);
 }
}

Sample Output:

Orginal TreeMap content: {10=Red, 20=Green, 30=Black, 40=White, 50=Pink
}                                                                      
Sub map key-values: {20=Green, 30=Black}

Java Code Editor:

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Java: Tips of the Day

getEnumMap

Converts to enum to Map where key is the name and value is Enum itself.

public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
    return Arrays.stream(enumClass.getEnumConstants())
            .collect(Collectors.toMap(Enum::name, Function.identity()));
}

Ref: https://bit.ly/3xXcFZt