Most students understand graph theory, but fail when it comes to actual implementation in Java
This video fixes that.

In today’s lecture, I implemented Adjacency Matrix Graph from scratch in Java, exactly the way it is expected in coding interviews and real applications.

TIMESTAMPS (Java Graph Implementation)
0:00 - Implementing the Adjacency Matrix in Java (Step-by-Step)
1:27 - Core Concept: The Adjacency Matrix Data Structure Explained
1:44 - Java Implementation: Initializing the 2D Array Matrix
3:44 - Writing the addEdge Logic: Supporting Undirected & Weighted Graphs
4:23 - Logic Deep Dive: Directed vs. Undirected Graph Implementation
5:22 - Handling Edge Weights: Weighted vs. Unweighted Graph Logic 8:03 - removeEdge Method: Efficiently Deleting Connections in Java
8:45 - hasEdge Method: Constant Time O(1) Connection Check
9:47 - Visualizing the Matrix: Writing a Custom displayGraph Method
11:05 - Main Method: Object Instantiation & Vertices Definition
11:24 - Building the Graph: Linking Vertices with Weights
12:13 - Executing the Code: Live Matrix Display Output
12:55 - Final Testing: Verifying removeEdge & hasEdge Methods

We started from basic graph concept, then moved step-by-step toward a fully working undirected + weighted adjacency matrix graph.

WHAT YOU WILL LEARN IN THIS VIDEO:
What is Adjacency Matrix Graph
How graph is represented using a 2D array in Java
Creating Graph class in IntelliJ IDEA
Initializing adjacency matrix properly
Implementing addEdge() method
Implementing removeEdge() method
Implementing hasEdge() method
Implementing display() method
Understanding logic behind each method
Implementing Undirected Graph using Adjacency Matrix
Implementing Weighted Graph using Adjacency Matrix
Running the program and analyzing output

Interview Insight:
In interviews, companies don’t just ask “What is Adjacency Matrix?”
They ask:
How do you add / remove edges efficiently?
How do you check edge existence in O(1)?
How would you modify it for weighted graphs?
This video answers all of that with clean Java code and logic explanation.

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