CartoonGram

University project — 3rd year, Observer Design Pattern

Team: Vleju Cosmin Eugen, Slătineanu Andreea-Elena

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What's this?

A social network simulator built in Java Swing with cartoon characters as users. It's an implementation of the Observer design pattern — characters post content, and followers get notified in real time when someone they follow publishes something.

The feed shows posts from Tom (Tom & Jerry), Jake and Princess Bubblegum (Adventure Time), Gumball and Darwin (The Amazing World of Gumball). You can follow/unfollow, like posts (custom heart icon drawn with Java2D Bezier curves), and leave comments (animated slide-in section).

The follow system uses a custom Observer pattern — each character is a Subject with its own list of Observers. When you hit Follow, both the Followers window and the button itself update instantly, without the character knowing who follows it.

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How the Observer pattern works here

• Subject — each character (FollowSubject) holds a list of observers and a follow/unfollow state
• Observers — the FollowButton toggles its label, and a Follower object adds/removes the name from the Following window
• When you click Follow, setFollowed() triggers notifyObservers(), which calls update() on everything attached

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What it looks like

The UI is a 400×600 phone-like window with scrollable feed, profile pics, post images, follow buttons, likes, and a bottom nav bar. Custom drawn heart icon for likes (empty/filled states), smooth comment section animation, and an animated scroll-to-top button.

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Running it

git clone https://github.com/papadie23/CartoonGram.git
cd CartoonGram

# Compile (requires JDK)
javac -d bin src/pk1/*.java

# Run
java -cp bin pk1.GUIinit

Opens a 400×600 Swing window.

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Screenshots

Main feed

Comment section

Following window

Post transitions

Follow state change

Following window update

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Tech

Java, Swing, Java2D, custom Observer pattern

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Why we built this

Part of our 3rd year software engineering coursework — to understand how the Observer pattern works under the hood, applied to something fun rather than a boring tutorial example.