implementing ConcurrentModificationException in Java 8 while Iterating Over a HashMap
I'm trying to figure out I'm integrating two systems and I'm maintaining legacy code that I've searched everywhere and can't find a clear answer. I'm experiencing a `ConcurrentModificationException` when trying to iterate over a `HashMap` while simultaneously modifying its entries. I'm using Java 8, and the behavior occurs in the following block of code: ```java Map<String, Integer> map = new HashMap<>(); map.put("A", 1); map.put("B", 2); map.put("C", 3); for (String key : map.keySet()) { if (key.equals("B")) { map.put("D", 4); // Modifying during iteration } System.out.println(key + " : " + map.get(key)); } ``` The `ConcurrentModificationException` is thrown at runtime, and I understand that this is due to modifying the collection while iterating over it. I tried using an `Iterator` to remove an entry instead, but I'm still working with issues with adding new entries during the iteration. Here’s the code I attempted with `Iterator`: ```java Iterator<String> iterator = map.keySet().iterator(); while (iterator.hasNext()) { String key = iterator.next(); if (key.equals("B")) { map.put("D", 4); // Still modifies during iteration } System.out.println(key + " : " + map.get(key)); } ``` I’ve read that using `ConcurrentHashMap` could be a solution, but I’m uncertain if it would suit my case since I still want to use a simple key-value pair structure. Is there a recommended approach to safely modify a `HashMap` while iterating over it without running into this exception? Any suggestions or best practices would be greatly appreciated! For context: I'm using Java on Windows. What's the best practice here? I've been using Java for about a year now. Any pointers in the right direction? Any feedback is welcome!