A-Streams: Use streams where loops only filter, map or join

src/main/java/ted/Storage.java

@@ -70,10 +70,9 @@ public void save(TaskList tasks) throws TedException {
                 Files.createDirectories(parentDir);
             }
 
-            List<String> lines = new ArrayList<>();
-            for (Task task : tasks.asList()) {
-                lines.add(task.toSaveFormat());
-            }
+            List<String> lines = tasks.asList().stream()
+                    .map(Task::toSaveFormat)
+                    .toList();
             Files.write(dataFile, lines);
         } catch (IOException e) {
             throw new TedException("Unable to save tasks to " + dataFile

src/main/java/ted/command/CommandType.java

@@ -1,5 +1,8 @@
 package ted.command;
 
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
 import ted.TedException;
 
 /**
@@ -64,14 +67,11 @@ public String getKeyword() {
      * @throws TedException if no command uses that keyword.
      */
     public static CommandType fromKeyword(String keyword) throws TedException {
-        for (CommandType command : values()) {
-            if (command.keyword.equals(keyword)) {
-                return command;
-            }
-        }
-
-        throw new TedException("I don't recognise \"" + keyword + "\". "
-                + "I understand: " + listKeywords() + ".");
+        return Arrays.stream(values())
+                .filter(command -> command.keyword.equals(keyword))
+                .findFirst()
+                .orElseThrow(() -> new TedException("I don't recognise \"" + keyword + "\". "
+                        + "I understand: " + listKeywords() + "."));
     }
 
     /**
@@ -82,10 +82,8 @@ public static CommandType fromKeyword(String keyword) throws TedException {
      * @return the keywords, separated by commas.
      */
     private static String listKeywords() {
-        String[] keywords = new String[values().length];
-        for (int i = 0; i < values().length; i++) {
-            keywords[i] = values()[i].keyword;
-        }
-        return String.join(", ", keywords);
+        return Arrays.stream(values())
+                .map(CommandType::getKeyword)
+                .collect(Collectors.joining(", "));
     }
 }

src/main/java/ted/task/TaskList.java

@@ -93,13 +93,9 @@ public boolean isEmpty() {
      */
     public TaskList find(String keyword) {
         String lowerCaseKeyword = keyword.toLowerCase();
-        TaskList matches = new TaskList();
-        for (Task task : tasks) {
-            if (task.getDescription().toLowerCase().contains(lowerCaseKeyword)) {
-                matches.add(task);
-            }
-        }
-        return matches;
+        return new TaskList(tasks.stream()
+                .filter(task -> task.getDescription().toLowerCase().contains(lowerCaseKeyword))
+                .toList());
     }
 
     /**