Java Collection, TreeMap Exercises: Get the greatest key less than or equal to the given key

Java Collection, TreeMap Exercises: Exercise-12 with Solution

Write a Java program to get the greatest key less than or equal to the given key.

Sample Solution:-

Java Code:

import java.util.*;
import java.util.Map.Entry;  
public class Example12 {  
      public static void main(String args[]) {
  // Create a tree map
  TreeMap < Integer, String > tree_map1 = new TreeMap < Integer, String > ();
  // Put elements to the map 
  tree_map1.put(10, "Red");
  tree_map1.put(20, "Green");
  tree_map1.put(40, "Black");
  tree_map1.put(50, "White");
  tree_map1.put(60, "Pink");

  System.out.println("Orginal TreeMap content: " + tree_map1);
  System.out.println("Checking the entry for 10: ");
  System.out.println("Key is: " + tree_map1.floorKey(10));
  System.out.println("Checking the entry for 30: ");
  System.out.println("Key is: " + tree_map1.floorKey(30));
  System.out.println("Checking the entry for 70: ");
  System.out.println("Key is: " + tree_map1.floorKey(70));

Sample Output:

Orginal TreeMap content: {10=Red, 20=Green, 40=Black, 50=White, 60=Pink
Checking the entry for 10:                                             
Key is: 10                                                             
Checking the entry for 30:                                             
Key is: 20                                                             
Checking the entry for 70:                                             
Key is: 60

Java Code Editor:

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Java: Tips of the Day


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