In the below example I have described "how to add or merge two array list?". Here I have created two array String  a[],String b[], then I have initialize values in array . After this I have created arrayList and merge value String a[] and String b[]. You can see below program it will clearly describe you How to Merge two array list.

public class Add {
  public static void main(String args[]){
    String a[] = {"a", "b", "c"};
    String b[] = {"d", "e","f","g" };

    List<String> list = new ArrayList<String>(Arrays.asList(a));
 
 // here merge  String a[], String b[] values

    list.addAll(Arrays.asList(b));
    Object [] c = list.toArray();
    System.out.println(Arrays.toString(c));
   
  }
}

 output :  [a, b, c, d, e, f, g]