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Java TreeMap remove() Method with Example

TreeMap Class putAll() method: Here, we are going to learn about the putAll() method of TreeMap Class with its syntax and example.
Submitted by Preeti Jain, on February 29, 2020

TreeMap Class putAll() method

• putAll() method is available in java.util package.
• putAll() method is used to remove the key-value pairs linked with the given key element (key_ele) that exists in this TreeMap.
• putAll() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• putAll() method may throw an exception at the removing mappings.
  • ClassCastException: This exception may throw when the given element is incompatible to compare.
  • NullPointerException: This exception may throw when the given parameter is null exists.

Syntax:

    public Value remove(Object key_ele);

Parameter(s):

• Object key_ele – represents the key element for which key-value pairs is to be removed when exists.

Return value:

The return type of the method is void, it returns the old value linked with the given key element otherwise it returns null.

Example:

// Java program to demonstrate the example 
// of Value remove(Object key_ele) method 
// of TreeMap 

import java.util.*;

public class RemoveOfTreeMap {
    public static void main(String[] args) {
        // Instantiates TreeMap
        TreeMap < Integer, String > tm = new TreeMap < Integer, String > ();

        // By using put() method is
        // to put the key-value pairs in
        // treemap tm
        tm.put(1, "C");
        tm.put(4, "C++");
        tm.put(3, "Java");
        tm.put(2, "Php");

        // Display TreeMap tm
        System.out.println("tm: " + tm);

        // By using remove(2) method is
        // to remove the key-value pairs
        // exists at the given key element
        // "2" when exists
        tm.remove(2);

        // Display updated TreeMap tm
        System.out.println("tm.remove(2): " + tm);
    }
}

Output

tm: {1=C, 2=Php, 3=Java, 4=C++}
tm.remove(2): {1=C, 3=Java, 4=C++}