﻿ Java: A key-value mapping using a map's greatest, least key

# Java Collection, TreeMap Exercises: Get a key-value mapping associated with the greatest key and the least key in a map

## Java Collection, TreeMap Exercises: Exercise-8 with Solution

Write a Java program to get a key-value mapping associated with the greatest key and the least key in a map.

Sample Solution:-

Java Code:

``````import java.util.*;
import java.util.Map.Entry;
public class Example8 {
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("C1", "Red");
tree_map1.put("C2", "Green");
tree_map1.put("C3", "Black");
tree_map1.put("C4", "White");

System.out.println("Orginal TreeMap content: " + tree_map1);
System.out.println("Greatest key: " + tree_map1.firstEntry());
System.out.println("Least key: " + tree_map1.lastEntry());
}
}
``````

Sample Output:

```Orginal TreeMap content: {C1=Red, C2=Green, C3=Black, C4=White}
Greatest key: C1=Red
Least key: C4=White ```

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