str.substring equals; str.charAt ==; str.endsWith

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

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+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.
+