Date: 2016jun8
Update: 2025jul17
Language: Java
Keywords: duplicate, clone
Q. Java: Quick way to make a copy of an ArrayList
A. Usually I prefer to copy it in the constructor:
ArrayList<String> theClone = new ArrayList<String>(theOriginal);
Here's a full demo showing two ways to do it:
import java.util.ArrayList;
class Demo {
public static void main(String[] args) {
// Make "original" ArrayList
ArrayList<String> theOriginal = new ArrayList<String>();
theOriginal.add("one");
theOriginal.add("two");
theOriginal.add("three");
// You can make a copy in the constructor
ArrayList<String> theCopy1 = new ArrayList<String>(theOriginal);
// Or you can copy using `addAll()`
ArrayList<String> theCopy2 = new ArrayList<String>();
theCopy2.addAll(theOriginal);
}
}