Flash cards
Review the key moves
1/4
Core idea
What is the main idea behind Java HashMap put() Method?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
1Quick choice
Which statement best captures the main point of this lesson?
2Fill blank
Complete the missing token from the example code.
___ java.util.HashMap;3Order
Put the learning moves in the order that makes the concept easiest to apply.
The put() method writes an entry into the map.
Definition and Usage
Java HashMap put() Method
❮ HashMap Methods
Example
import java.util.HashMap;
public class Main {
public static void main(String[] args) {
HashMap<String, String> capitalCities = new HashMap<String, String>();
capitalCities.put("England", "London");
capitalCities.put("Germany", "Berlin");
capitalCities.put("Norway", "Oslo");
capitalCities.put("USA", "Washington DC");
System.out.println(capitalCities);
}
}Definition and Usage
The put() method writes an entry into the map. If an entry with the same key already exists then the value of that entry will be changed.
Syntax
public V put(K
key , V
value )K and V refer to the data types of the keys and values of the map.
Parameter Values
| Parameter | Description |
|---|---|
| key | Required. The key of the map entry. |
| value | Required. The value of the map entry. |
Technical Details
| Returns: | If an entry already existed with the specified key then it returns the value of that entry before overwriting it, otherwise it returns null . |
|---|