Accept two list from the user and find common element from the both list in java?

Question

For this I have to take two list as input from user and then I have to compare it. How to do it in java language.

Answer 1

If you want to find common elements between two string ArrayLists

public static ArrayList<String> commonElements(ArrayList<String> a, ArrayList<String> b){

   // Initialize arraylist to return
   ArrayList<String> toReturn = new ArrayList<String>();

   // Iterate across elements of 'a'
   for (String s : a){

      // If the element is in 'b'
      if (b.contains(s)){

         // Add it to 'toReturn'
         toReturn.add(s);
      
      }

   }
  
   return toReturn;
}

Example

public static void main(String[] args) {
   ArrayList<String> a = new ArrayList<String>();
   ArrayList<String> b = new ArrayList<String>();
   a.add("hi");
   a.add("bye");
   a.add("welcome");
   a.add("goodbye");
   b.add("hi");
   b.add("hello");
   b.add("goodbye");
   for (String s : commonElements(a, b)){
      System.out.println(s);
   }
}

Output

hi
goodbye