TreeMap in Java

TreeMap is Red-Black tree based NavigableMap implementation. It is sorted according to the natural ordering of its keys.

Example

import java.util.Map;
import java.util.TreeMap;

public class Detective {

	public static void main(String[] args) {

		//The entries in a TreeMap are always sorted based on the natural ordering of the keys
		Map<Integer, String> statements = new TreeMap<Integer, String>();

		// Inserting statements into the map
		statements.put(5, "shouting");
		statements.put(1, "fight");
		statements.put(7, "fleeing");
		statements.put(9, "gunshot");
		statements.put(15, "panic");
		statements.put(3, "anger");
		statements.put(8, "shouting");
		
		// printing the already sorted map
		printStatements(statements);
	}

	public static void printStatements(Map<Integer, String> map) {
		for (Map.Entry<Integer, String> entry : map.entrySet()) {
			System.out.println( "Key : " + entry.getKey() +  " Value : " +entry.getValue());
		}
	}
}

Output

Key : 1 Value : fight
Key : 3 Value : anger
Key : 5 Value : shouting
Key : 7 Value : fleeing
Key : 8 Value : shouting
Key : 9 Value : gunshot
Key : 15 Value : panic

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