Add SkillLevel in Game

src/main/java/seedu/address/model/game/Game.java

@@ -20,6 +20,7 @@ public class Game {
 
     public final String gameName;
     public final Username username;
+    public final SkillLevel skillLevel;
 
     /**
      * Constructs a {@code Game} without a username.
@@ -31,6 +32,7 @@ public Game(String gameName) {
         checkArgument(isValidGameName(gameName), MESSAGE_CONSTRAINTS);
         this.gameName = gameName;
         this.username = null;
+        this.skillLevel = null;
     }
 
     /**
@@ -43,6 +45,20 @@ public Game(String gameName, String username) {
         checkArgument(isValidGameName(gameName), MESSAGE_CONSTRAINTS);
         this.gameName = gameName;
         this.username = new Username(username);
+        this.skillLevel = null;
+    }
+
+    /**
+     * Constructs a {@code Game} with a username.
+     *
+     * @param gameName A valid Game name.
+     */
+    public Game(String gameName, String username, SkillLevel skillLevel) {
+        requireNonNull(gameName);
+        checkArgument(isValidGameName(gameName), MESSAGE_CONSTRAINTS);
+        this.gameName = gameName;
+        this.username = new Username(username);
+        this.skillLevel = new SkillLevel(skillLevel);
     }
 
     /**

src/main/java/seedu/address/model/game/SkillLevel.java

@@ -0,0 +1,73 @@
+package seedu.address.model.game;
+
+import static java.util.Objects.requireNonNull;
+import static seedu.address.commons.util.AppUtil.checkArgument;
+
+/**
+ * Describes the Person's skill level in a Game.
+ */
+public class SkillLevel {
+
+    private static final String MESSAGE_CONSTRAINTS =
+            "Skill Level should not be blank";
+
+    /*
+     * Regex expression matches Strings that contain at least one non-whitespace character.
+     */
+    private static final String VALIDATION_REGEX = "^(?!\\s*$).+";
+
+    private final String skillLevel;
+
+    /**
+     * Constructs a {@code SkillLevel}.
+     *
+     * @param skillLevel a valid skill level or rank.
+     */
+    public SkillLevel(String skillLevel) {
+        requireNonNull(skillLevel);
+        checkArgument(isValidSkillLevel(skillLevel), MESSAGE_CONSTRAINTS);
+        this.skillLevel = skillLevel;
+    }
+
+    /**
+     * Returns true if a given string is a valid SkillLevel.
+     */
+    public static boolean isValidSkillLevel(String test) {
+        return test.matches(VALIDATION_REGEX);
+    }
+
+    /**
+     * Getter for skillLevel field.
+     */
+    public String getSkillLevel() {
+        return skillLevel;
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (other == this) {
+            return true;
+        }
+
+        // instanceof handles nulls
+        if (!(other instanceof SkillLevel)) {
+            return false;
+        }
+
+        SkillLevel otherName = (SkillLevel) other;
+        return skillLevel.equals(otherName.skillLevel);
+    }
+
+    @Override
+    public int hashCode() {
+        return skillLevel.hashCode();
+    }
+
+    /**
+     * Format state as text for viewing.
+     */
+    public String toString() {
+        return skillLevel;
+    }
+
+}