Java coding interview practice
48 test-checked Java exercises for the live-coding interview: strings, collections, streams, records, sealed types and generics, compiled on JDK 21. Free.
Topics
- Strings: 6 exercises
- Collections: 6 exercises
- Streams & lambdas: 6 exercises
- Records, classes & interfaces: 6 exercises
- Generics & Optional: 6 exercises
- Exceptions & validation: 6 exercises
- Algorithms & recursion: 6 exercises
- Modern Java: 6 exercises
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.