Add FindCommand class.

src/main/java/commands/FindCommand.java

@@ -0,0 +1,42 @@
+package commands;
+
+import data.task.Task;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class FindCommand extends Command {
+
+    public static final String COMMAND_WORD = "find";
+
+    public static final String MESSAGE_USAGE = COMMAND_WORD
+            + ": Displays all tasks as a list with target key word(s)."
+            + " -Example: " + COMMAND_WORD
+            + " read";
+
+    /** Offset required to convert between 1-indexing and 0-indexing.  */
+    public static final int DISPLAYED_INDEX_OFFSET = 1;
+
+    private final String keyword;
+
+    public FindCommand(String keyword) {
+        this.keyword = keyword;
+    }
+
+    public String execute() {
+        List<Task> matchingTasks = taskList.findMatch(keyword);
+
+        if (matchingTasks.isEmpty()) {
+            return "You don't have any matching task in your list.";
+        }
+
+        StringBuilder sb = new StringBuilder();
+        sb.append("Here are the matching tasks in your list:").append("\n");
+        int size = matchingTasks.size();
+        for (int i = 0; i < size - DISPLAYED_INDEX_OFFSET; i += 1) {
+            sb.append((i + DISPLAYED_INDEX_OFFSET)).append(". ").append(matchingTasks.get(i).toString()).append("\n");
+        }
+        sb.append(size).append(". ").append(matchingTasks.get(size - 1).toString());
+        return sb.toString();
+    }
+}

src/main/java/commands/HelpCommand.java

@@ -18,6 +18,7 @@ public String execute() {
                 + "\n" + TodoCommand.MESSAGE_USAGE
                 + "\n" + DeadlineCommand.MESSAGE_USAGE
                 + "\n" + EventCommand.MESSAGE_USAGE
+                + "\n" + FindCommand.MESSAGE_USAGE
                 + "\n" + MarkCommand.MESSAGE_USAGE
                 + "\n" + UnmarkCommand.MESSAGE_USAGE
                 + "\n" + DeleteCommand.MESSAGE_USAGE;

src/main/java/data/TaskList.java

@@ -3,7 +3,6 @@
 import data.task.Task;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 
 public class TaskList {
@@ -41,4 +40,14 @@ public void deleteTask(int taskIndex) {
     public List<Task> getAllTasks() {
         return this.tasks;
     }
+
+    public List<Task> findMatch(String keyWork) {
+        List<Task> internalList = new ArrayList<>();
+        for (Task task : tasks) {
+            if (task.getTaskName().contains(keyWork)) {
+                internalList.add(task);
+            }
+        }
+        return internalList;
+    }
 }

src/main/java/data/task/Task.java

@@ -9,6 +9,10 @@ public Task(String taskName) {
         this.isDone = false;
     }
 
+    public String getTaskName() {
+        return taskName;
+    }
+
     public String getStatusIcon() {
         return (isDone ? "X" : " "); // mark done task with X
     }

src/main/java/parser/Parser.java

@@ -5,6 +5,7 @@
 import commands.DeleteCommand;
 import commands.EventCommand;
 import commands.ExitCommand;
+import commands.FindCommand;
 import commands.HelpCommand;
 import commands.InvalidCommand;
 import commands.ListCommand;
@@ -61,6 +62,14 @@ public Command parseCommand(String userInput) {
                         "Use: event <description> /from <start_time> /to <end_time>");
             }
 
+        case FindCommand.COMMAND_WORD:
+            try {
+                String keyword = inputParts[1];
+                return new FindCommand(keyword);
+            } catch (ArrayIndexOutOfBoundsException e) {
+                return new WrongFormatCommand("Invalid format! Use: Find <keyword>");
+            }
+
         case MarkCommand.COMMAND_WORD:
             try {
                 int taskIndex = Integer.parseInt(inputParts[1]);