Flash cards
Review the key moves
1/4
Core idea
What is the main idea behind Java HashMap putAll() 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 putAll() method writes all of the entries from another map into the map.
Definition and Usage
Java HashMap putAll() 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");
HashMap<String, String> moreCities = new HashMap<String, String>();
moreCities.put("Canada", "Ottawa");
moreCities.put("Japan", "Tokyo");
capitalCities.putAll(moreCities);
System.out.println(capitalCities);
}
}Definition and Usage
The putAll() method writes all of the entries from another map into the map. If entries exist with the same keys then the values of these entries will be changed.
One of the following
public void putAll(Map
map )K and V refer to the data types of the keys and values of the map.
Parameter Values
| Parameter | Description |
|---|---|
| map | Required. Another map containing entries to be added to the map. |
Technical Details
| Throws: | NullPointerException - If the map argument is null . |
|---|