Learning Path
7 Lessons
1
Tutorial
Introduction to Arrays
What is a program? Primitive vs Reference types. Why we need arrays. Declaration, creation, and initialization.
2
Exercises
1D Arrays Exercises
15 interactive questions testing your understanding of primitive vs reference variables, array manipulation, and pass by value/reference.
3
Tutorial
2D and 3D Arrays
The computer only understands 1D arrays! Learn how 2D arrays are "array of arrays" and 3D arrays are "array of 2D arrays".
4
Tutorial
Ragged (Jagged) Arrays
Why ragged arrays exist and when to use them. Creating arrays where each row has different number of columns.
5
Exercises
2D and 3D Arrays Exercises
15 interactive questions covering 2D arrays, 3D arrays, ragged arrays, and the array of arrays concept.
6
Practical
Reading 2D Ragged Arrays from File
Learn to read variable-length student marks from a text file using nextLine() and split(). Includes downloadable Java code and data file.
7
Practical
Reading 3D Ragged Arrays from File
Build on 2D skills to read a Department → Students → Courses structure (CS, IT, IS) from file. Complete line-by-line explanation.
📚 Key Concepts You'll Learn
Reference Variables
Understand how arrays are stored via references, not directly in variables.
Array of Arrays
2D and 3D arrays are NOT tables - they're arrays pointing to other arrays!
Memory Layout
Visualize how arrays are stored in Stack and Heap memory.
Ragged Arrays
Create flexible arrays where each row can have different sizes.
Reading from Files
Load ragged arrays from text files using Scanner, nextLine(), and split().