How to merge two ArrayLists without duplicates? [duplicate]

Answer 1

Try this kind of thing. As Set doesn't allow duplicates you can add only the changes

ArrayList a=new ArrayList<>();
a.add("a");
a.add("b");
ArrayList b=new ArrayList<>();
a.add("a");
a.add("c");
Set s=new HashSet();
s.addAll(a);
s.addAll(b);
a=new ArrayList<>(s);
for(String r:a){
    System.out.println(r);
}