Question

Write a method doubleList that takes an ArrayList of Strings as a parameter and that replaces every string with two of that string. For example, if the list stores the values {"how", "are", "you?"} before the method is called, it should store the values {"how", "how", "are", "are", "you?", "you?"} after the method finishes executing.

Answer 1

Answer:

// Method to double the content in a list

// Method receives an arraylist as parameter

public static void doubleList(ArrayList<String> stringlist) {

 // Create a new array list to hold the new content

 ArrayList<String> newList = new ArrayList<>();

 // Create a loop that cycle through the string list

 // For every cycle, get the current content of the list

 // and add it twice to the new list

 for (int i = 0; i < stringlist.size(); i++) {

  newList.add(stringlist.get(i));

  newList.add(stringlist.get(i));

 }

 // Copy the content of the new list back to the string list

 stringlist = newList;

 // Display the result

 System.out.println(stringlist);

}

Explanation:

Please go through the comments in the code for better understanding and readability.

Hope this helps!