How do I copy collections in Java?

How do I copy collections in Java?

You can copy collections in Java using methods like addAll(), clone(), or by using the constructor of the collection.

Can you show me an example using ArrayList?

Sure! Here's an example:

ArrayList<String> original = new ArrayList<>();
original.add("A");
original.add("B");

ArrayList<String> copy = new ArrayList<>(original);

What about using HashMap?

For HashMap, you can use the constructor as well:

HashMap<String, Integer> originalMap = new HashMap<>();
originalMap.put("One", 1);
originalMap.put("Two", 2);

HashMap<String, Integer> copyMap = new HashMap<>(originalMap);

Are there any performance considerations?

Yes, copying large collections can be expensive in terms of time and memory. It's important to consider the size and type of collection.