Java Collection, TreeMap Exercises: Get the first (lowest) key and the last (highest) key currently in a map
Java Collection, TreeMap Exercises: Exercise-9 with Solution
Write a Java program to get the first (lowest) key and the last (highest) key currently in a map.
Sample Solution:-
Java Code:
import java.util.*;
import java.util.Map.Entry;
public class Example9 {
public static void main(String args[]) {
// Create a tree map
TreeMap <String,String> tree_map1 = new TreeMap <String,String> ();
// Put elements to the map
tree_map1.put("C2", "Red");
tree_map1.put("C1", "Green");
tree_map1.put("C4", "Black");
tree_map1.put("C3", "White");
System.out.println("Orginal TreeMap content: " + tree_map1);
System.out.println("Greatest key: " + tree_map1.firstKey());
System.out.println("Least key: " + tree_map1.lastKey());
}
}
Sample Output:
Orginal TreeMap content: {C1=Green, C2=Red, C3=White, C4=Black} Greatest key: C1 Least key: C4
Java Code Editor:
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Previous: Get a key-value mapping associated with the greatest key and the least key in a map.
Next: Get a reverse order view of the keys contained in a given map.
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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
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