Created
April 17, 2015 11:41
-
-
Save jessalfredsen/8ee964dc333b732bea85 to your computer and use it in GitHub Desktop.
deepMerge in Java Maps
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import java.util.HashMap; | |
| import java.util.Map; | |
| import java.util.List; | |
| import java.util.ArrayList; | |
| public class HelloWorld{ | |
| public static void main(String []args){ | |
| System.out.println("Hello World"); | |
| Map vehicles = new HashMap(); | |
| // Add some vehicles. | |
| vehicles.put("BMW", 5); | |
| vehicles.put("Mercedes", 3); | |
| vehicles.put("Audi", 4); | |
| vehicles.put("Ford", 10); | |
| ArrayList wheels = new ArrayList(); | |
| wheels.add(15); | |
| wheels.add(16); | |
| vehicles.put("wheels", wheels); | |
| Map vehicles2 = new HashMap(); | |
| vehicles2.put("Ford", 20); | |
| ArrayList wheels2 = new ArrayList(); | |
| wheels2.add(18); | |
| vehicles2.put("wheels", wheels2); | |
| System.out.println("Total vehicles: " + vehicles.size()); | |
| System.out.println("wheels: " + vehicles.get("wheels")); | |
| Map vehicles_final = deepMerge(vehicles, vehicles2); | |
| System.out.println("Total vehicles: " + vehicles_final.size()); | |
| System.out.println("wheels: " + vehicles_final.get("wheels")); | |
| } | |
| // This is fancier than Map.putAll(Map) | |
| private static Map deepMerge(Map original, Map newMap) { | |
| for (Object key : newMap.keySet()) { | |
| if (newMap.get(key) instanceof Map && original.get(key) instanceof Map) { | |
| Map originalChild = (Map) original.get(key); | |
| Map newChild = (Map) newMap.get(key); | |
| original.put(key, deepMerge(originalChild, newChild)); | |
| } else if (newMap.get(key) instanceof List && original.get(key) instanceof List) { | |
| List originalChild = (List) original.get(key); | |
| List newChild = (List) newMap.get(key); | |
| for (Object each : newChild) { | |
| originalChild.add(each); | |
| } | |
| } else { | |
| original.put(key, newMap.get(key)); | |
| } | |
| } | |
| return original; | |
| } | |
| } | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment