Programming Academy
Learn Java with a real compiler right on the page: println and Scanner, decisions and loops, arrays, ArrayLists and strings, methods, classes, inheritance and interfaces, then sorting, searching, 2D arrays, exceptions and HashMap.
55 lessons, about 360 minutes so far · the first 3 lessons free
55 lessons
What Java is, the parts every Java program has, and your first programs: print words and numbers with println, write comments, and read what the compiler tells you when something's wrong.
Keep values in variables (int, double, char, boolean, String), do sums with them, and read what the user types with Scanner.
Let a program choose: if and else, comparing values, combining conditions with &&, || and !, else if, and switch.
Repeat things without copying lines: while, for and do-while loops, break and continue, and loops inside loops.
Keep many values under one name: arrays, then ArrayLists that grow, the for-each loop, totals, the biggest and searching.
Work with text: length and charAt, joining and comparing with equals, substring and indexOf, and building text with StringBuilder.
Split a program into methods of your own: parameters and return values, overloading, and methods that call themselves.
Make your own types: classes with fields and methods, constructors, private fields with getters, and lists of objects.
Build on other classes: extends and super, overriding methods, abstract classes and interfaces, and a final project.
The classic algorithms every exam asks for: linear and binary search, bubble sort and selection sort, then 2D arrays for tables and matrices.
Handle problems without crashing (try, catch, finally and throw), then look things up by name with HashMap, and finish with a word-count project.
