In Java, when it comes to handling duplicate keys in a TreeMap, the class does not allow duplicate keys. If we try to insert a key-value pair with a key that already exists in the TreeMap, the new value will override the existing one associated with that key.
Declaration of a TreeMap:
TreeMap<KeyType, ValueType> treeMap = new TreeMap<>();
Program to Handle Duplicate Keys in a TreeMap in Java
Below is a demonstration of a Program to Handle Duplicate Keys in a TreeMap in Java:
Java
// Java program to handle duplicate keys in a TreeMap import java.util.TreeMap;
class GFG {
public static void main(String[] args) {
// Creating a TreeMap
TreeMap<Integer, String> treeMap = new TreeMap<>();
// Adding key-value pairs
treeMap.put( 1 , "One" );
treeMap.put( 2 , "Two" );
treeMap.put( 3 , "Three" );
// Attempting to add a duplicate key
treeMap.put( 2 , "New Two" ); // This will overwrite the value for key 2
// Displaying the contents of the TreeMap
System.out.println( "TreeMap contents: " + treeMap);
}
} |
Output
TreeMap contents: {1=One, 2=New Two, 3=Three}
Explanation of the Program:
-
In the above program, it creates a
TreeMap
namedtreeMap
. -
Key-value pairs are added to the
treeMap
. -
An attempt is made to insert a duplicate key
2
with the value"New Two"
. SinceTreeMap
does not allow duplicate keys, the existing value associated with key2
(“Two”) will be replaced by the new value (“New Two”). -
The contents of the
treeMap
are displayed.