courses / java

learn java

Three levels, from never written code to writing it like a professional. Write once, run anywhere.

build things that are actually useful.

For people who finished Level 1, or can already write small programs with variables, decisions, loops and functions.

1 unit 1 Lists that grow Keep as many things as you like, in order, and change them as you go. 0 of 4 · 37 min
  1. A list that grows9 min
  2. Changing a list9 min
  3. Lists of numbers9 min
  4. Searching and sorting lists10 min
2 unit 2 Maps and sets Look things up by name and keep every value only once. 0 of 4 · 38 min
  1. Look it up with a HashMap9 min
  2. Updating a map10 min
  3. Looping over a map10 min
  4. No repeats with a HashSet9 min
3 unit 3 Build better objects Give your objects a proper start, skills of their own and some privacy. 0 of 4 · 39 min
  1. Constructors10 min
  2. Objects that do things10 min
  3. Keep your fields private10 min
  4. Objects that describe themselves9 min
4 unit 4 Shared, equal and fixed Share values across objects, compare them fairly and fix a set of choices. 0 of 4 · 41 min
  1. Shared boxes and constants10 min
  2. When are two objects equal?12 min
  3. Enums: a fixed set of choices9 min
  4. Enums with their own values10 min
5 unit 5 Family trees Build new classes on top of old ones and give them a shared shape. 0 of 4 · 41 min
  1. Inheritance10 min
  2. Overriding10 min
  3. Interfaces10 min
  4. Sort by your own rules11 min
6 unit 6 When things go wrong Catch problems, throw your own and keep your program running. 0 of 4 · 42 min
  1. Catching an exception10 min
  2. More catches and finally10 min
  3. Throwing your own problems10 min
  4. Checked exceptions and your own12 min
7 unit 7 Save your work Build text, save it in files and read it back. 0 of 4 · 43 min
  1. Building text with StringBuilder9 min
  2. Writing and reading a file11 min
  3. One line per record11 min
  4. Try-with-resources12 min
end of level 2 level check Build one small project with everything from this level. Pass it and your face levels up. see the check