Java TreeMap remove(Object key) Method Example

The remove(Object key) method of java.util.TreeMap class removes the mapping for this key from this TreeMap if present.

Signature

public V remove(Object key)

This method associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced. Throws java.lang.ClassCastException if the specified key cannot be compared with the keys currently in the map and java.lang.NullPointerException if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

Example

The following example shows the usage of java.util.TreeMap.remove(key) method.

public class RemoveMethodTreeMapExample 
{
    public static void main(String args[])
    {
        // create an empty TreeMap
        TreeMap<Integer,String>  treeMap1 = new TreeMap<Integer,String>();
        
        // use put() method to put elements to the TreeMap
        treeMap1.put(1,"Element1");
        treeMap1.put(2,"Element2");
        treeMap1.put(3,"Element3");
        treeMap1.put(4,"Element4");
        treeMap1.put(5,"Element5");
        
        //Print the elements of TreeMap before remove
        System.out.println("**Elements of TreeMap before remove**");
        for(Map.Entry<Integer,String> entry : treeMap1.entrySet())
        {
            System.out.println("Key : "+entry.getKey()+" ...."+"Value : "+entry.getValue());
        }
        
        //Print the value returned while removing
        System.out.println("Value returned : "+treeMap1.remove(3));
        
        //Print the elements of TreeMap after remove
        System.out.println("**Elements of TreeMap after remove**");
        for(Map.Entry<Integer,String> entry : treeMap1.entrySet())
        {
            System.out.println("Key : "+entry.getKey()+" ...."+"Value : "+entry.getValue());
        }
    }
}

Output

**Elements of TreeMap before remove**
Key : 1 ....Value : Element1
Key : 2 ....Value : Element2
Key : 3 ....Value : Element3
Key : 4 ....Value : Element4
Key : 5 ....Value : Element5
Value returned : Element3
**Elements of TreeMap after remove**
Key : 1 ....Value : Element1
Key : 2 ....Value : Element2
Key : 4 ....Value : Element4
Key : 5 ....Value : Element5

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