Question

I just want to know how to print out Strings in an ArrayList with a given certain value only for the output. For example: I input “Hot”, “Cold”, “Pressure”, “Pain”. What method/control statement should I use to make so that the output will only be the words with four letters?

Output:
“Cold”
“Pain”

It only prints “Cold” & “Pain” because they’re the only one with four elements.
Will the use of .set be useful?

Answer 1

As explained in the comments, you could iterate over the list. If this is a repeated operation, you could use a map to sort the strings by length. See below an example with the 2 solutions:

public static void main(String[] args) {
    List<String> list = Arrays.asList("Hot", "Cold", "Pressure", "Pain");

    //Solution 1
    for (String s : list) {
        if (s.length() == 4) {
            System.out.println(s); //prints Cold and Pain
        }
    }

    //Solution 2
    Map<Integer, List<String>> map = new HashMap<Integer, List<String>> ();
    for (String s : list) {
        int length = s.length();
        if (map.containsKey(length)) {
            map.get(length).add(s);
        } else {
            map.put(length, new ArrayList<String>(Arrays.asList(s)));
        }
    }

    System.out.println(map.get(4)); //prints [Cold, Pain]
    System.out.println(map.get(3)); //prints [Hot]
}