AI Prompt Generator for Java

Java’s own version history changes what a correct answer looks like more than most languages’. Records — compact, immutable data carriers — were finalized in Java 16; sealed classes, which restrict which other classes may extend or implement a type, in Java 17; pattern matching for switch and virtual threads (lightweight, JVM-managed threads for high-throughput I/O-bound code) both in Java 21. Java 25, released in September 2025, is the current LTS release. An assistant asked to refactor or write code with no version specified has no way to know whether any of those are actually usable — it either avoids them entirely (missing a genuine improvement available on your version) or suggests one that won’t compile on an older runtime, and it can’t tell which mistake it’s making without being told.

The same gap shows up around Spring. Spring Boot 2.x builds on the javax.* package namespace for the Jakarta specifications (persistence, validation, servlets); Spring Boot 3.x and later moved to jakarta.* for the same APIs, and Spring Boot 4 continues on jakarta.* under Jakarta EE 11 with a Java 17 baseline. The two namespaces are not interchangeable — code written against one will not compile against the other — and an assistant told only “Spring Boot,” with no version, will guess, sometimes mixing both namespaces in the same generated file. Naming the framework version turns that guess into a fact.

Testing has its own version split. JUnit 4’s API lives under org.junit (@Test, @Before, @RunWith); JUnit 5 and 6 use the Jupiter API under org.junit.jupiter.api (@Test, @BeforeEach, @ExtendWith) — different packages, different annotation names, and not designed to be mixed in one test class. An assistant with no stated test framework has no reason to prefer one over the other, and will sometimes import from both in the same generated file, which fails to compile rather than merely running the “wrong” style of test. The same applies to a mocking library: told to “mock the repository” with no library specified, an assistant might reach for Mockito syntax, EasyMock syntax, or a hand-written stub, inconsistently, prompt to prompt.

Framework choice also changes what a code review should actually look for. A Spring Boot or Jakarta EE project built on JPA has two review concerns that don’t apply to plain Java: transaction boundaries (whether @Transactional sits on the right method, with the right propagation) and the N+1 query pattern, where a loop over a parent entity triggers one additional query per child row instead of a single joined fetch. Neither shows up in code that isn’t using a JPA-backed framework, so a generic “review this code” prompt has no way to know to look for them — which is why this tool’s own code-review guidance only adds those two checks when a Spring Boot or Jakarta EE framework is actually selected.

This page pre-fills the form with a small, realistic Java example so the effect is visible immediately: a DiscountCalculator class with one method, apply(BigDecimal price, int percent), that validates both arguments and returns the discounted price rounded half-up to two decimal places — a normal case, two argument-validation edge cases, and a rounding behavior, which is exactly the shape a “write tests” prompt needs to produce boundary-value test cases rather than a single happy-path test. With Java 21, no framework, Maven, and JUnit 5 selected, the assistant is told precisely which test API to use and precisely which language-version features are safe to reach for — removing both kinds of guesswork the generic prompt below has no way to resolve on its own.