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What happens when we try to add a duplicate key into a HashMap object in java?
The HashMap is a class that implements the Map interface. It is based on the Hash table. It allows null values and null keys.
You can store key-value pairs in the HashMap object. Once you do so you can retrieve the values of the respective keys but, the values we use for keys should be unique
Duplicate values
The put command associates the value with the specified key. i.e. if we add a key-value pair where the key exists already, this method replaces the existing value of the key with the new value,
Example
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class DuplicatesInHashMap {
public static void main(String args[]) {
HashMap<String, Long> map = new HashMap<String, Long>();
map.put("Krishna", 9000123456L);
map.put("Rama", 9000234567L);
map.put("Sita", 9000345678L);
map.put("Bhima", 9000456789L);
map.put("Yousuf ", 9000456789L);
System.out.println("Values Stored . . . . . .");
//Retrieving the values of a Hash map
Iterator it1 = map.entrySet().iterator();
System.out.println("Contents of the hashMap are: ");
while(it1.hasNext()){
Map.Entry <String, Long> ele = (Map.Entry) it1.next();
System.out.print(ele.getKey()+" : ");
System.out.print(ele.getValue());
System.out.println();
}
map.put("Bhima", 0000000000L);
map.put("Rama", 0000000000L);
//Retrieving the values of a Hash map
Iterator it2 = map.entrySet().iterator();
System.out.println("Contents of the hashMap after inserting new key-value pair: ");
while(it2.hasNext()){
Map.Entry <String, Long> ele = (Map.Entry) it2.next();
System.out.print(ele.getKey()+" : ");
System.out.print(ele.getValue());
System.out.println();
}
}
}Output
Values Stored . . . . . . Contents of the hashMap are: Yousuf : 9000456789 Krishna : 9000123456 Sita : 9000345678 Rama : 9000234567 Bhima : 9000456789 Contents of the hashMap after inserting new key-value pair: Yousuf : 9000456789 Krishna : 9000123456 Sita : 9000345678 Rama : 0 Bhima : 0
Updated on: 15-Oct-2019
3K+ Views
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