Week 7: Enum, Generic Type, Streams, write to file, class diagram/11B. Sentences Ending with a Period

Write a method:
public static ArrayList<String> sentencesWithPeriod(ArrayList<String> sentences)

that takes a list of sentences as strings as its parameter.
The method returns a new list containing only those sentences from the original list that end with a period.
Use 'stream' for your solution



import java.util.Random;
import java.util.ArrayList;
import java.util.stream.Collectors;

public class Test {
    public static void main(String[] args) {
        final Random r = new Random();
        

        String[] sub = "Pike Perch Roach Rose Poppy Lily Rabbit Bunny Hare Java Python".split(" ");
        String[] ob = "fish flower plant animal mammal programming language".split(" ");

        ArrayList<String> sentences = new ArrayList<>();
        int m = r.nextInt(6) + 6;
        for (int i = 0; i < m; i++) {
            String sentence = sub[r.nextInt(sub.length)] + " is a " + ob[r.nextInt(ob.length)];
            sentence += r.nextInt(2) == 0 ? "." : "";
            sentences.add(sentence);
        }

        System.out.println("Sentences:");
        sentences.stream().forEach(s -> System.out.println("" + s));

        System.out.println("Sentences ending with a period:");
        sentencesWithPeriod(sentences).stream().forEach(s -> System.out.println(s));
    }


    //ADD
    public static ArrayList<String> sentencesWithPeriod(ArrayList<String> sentences) {
        // approach 1 - substring
        // substring() returns a new string 
        // => which is a reference type object 
        // => so compare using .equals()
        //https://stackoverflow.com/questions/5163785/how-do-i-get-the-last-character-of-a-string
        return sentences.stream().
                         filter(str -> str.substring(str.length() - 1).equals(".")).
                         collect(Collectors.toCollection(ArrayList::new));

                         
        // approach 2 - charAt
        // charAt() returns a char
        // => which is a primitive type
        // => so compare using '=='
        return sentences.stream().
                         filter(str -> str.charAt(str.length() - 1) == '.').
                         collect(Collectors.toCollection(ArrayList::new));

                         
        // approach 3 - endsWith
        // endsWith() returns a boolean
        // => naturally 'true' elements are kept
        return sentences.stream().
                         filter(str -> str.endsWith(".")).
                         collect(Collectors.toCollection(ArrayList::new));
        
    }





}




Sentences:
Bunny is a programming.
Pike is a plant.
Bunny is a mammal
Java is a flower
Hare is a animal
Lily is a programming.

Sentences ending with a period:
Bunny is a programming.
Pike is a plant.
Lily is a programming.