How do I implement a TreeMap in Java?

How do I implement a TreeMap in Java?

To implement a TreeMap in Java, you can use the TreeMap class from the java.util package. Here's a simple example:

import java.util.TreeMap;

public class TreeMapExample {
    public static void main(String[] args) {
        TreeMap<Integer, String> treeMap = new TreeMap<>();
        treeMap.put(1, "One");
        treeMap.put(2, "Two");
        treeMap.put(3, "Three");

        System.out.println(treeMap);
    }
}

This code creates a TreeMap, adds some key-value pairs, and prints the map.

What are the advantages of using TreeMap over HashMap?

TreeMap maintains a sorted order of its keys, which allows for range queries and ordered traversal. In contrast, HashMap does not guarantee any order.

Can I use custom objects as keys in a TreeMap?

Yes, you can use custom objects as keys in a TreeMap, but you need to ensure that your objects implement the Comparable interface or provide a Comparator when creating the TreeMap.

What happens if I try to insert a null key?

In a TreeMap, inserting a null key will throw a NullPointerException because TreeMap does not allow null keys.