#java

Questions from a fresher backend interview at a unicorn product company, covering Java, data structures, Firebase, networking, and concurrency.

A three-round Oracle interview experience in Gandhinagar, India, with the puzzles, Java, SQL, and string problems asked in each round.

Two firsthand accounts of Fresher Java Backend Developer interviews at a fintech company and an outsourcing company, with the OOP, Java core, database, and Spring questions asked.

A Java/Spring Boot Dockerfile on Alpine JRE with JVM tuning, graceful shutdown, a curl healthcheck, and OCI labels, balancing image size against maintainability.

A Java Dockerfile that automatically upgrades Gradle plugins and dependencies at build time and uses a compiled Java class as the healthcheck on a distroless runtime.

A Java Dockerfile that builds a minimal custom JRE with jlink and jdeps and runs it on a distroless base image with a busybox wget healthcheck.

An overview of four Dockerfile optimization approaches for Java/Spring Boot applications, compared by image size, security, and performance.

The most heavily optimized Java Dockerfile, combining a hand-picked jlink JRE, Spring Boot layered JARs, tini, SHA256-pinned Alpine, and a non-root CIS-compliant user.

How a .class file becomes a running application: loading and class identity, linking and verification, initialization, interpreter/JIT/AOT, threads and happens-before, heap allocation and GC roots, and JVMTI/JMX/JFR monitoring.

Why ExecutorService fan-out leaks threads and waits too long, and how StructuredTaskScope models subtasks as one unit: fork, join and close, joiner policies, timeout semantics, interrupt-based cancellation, JSON thread dumps, and the JDK 27 preview / JDK 28 final status.

Pointer to MicroProfile, an API library that provides tooling for building microservices in Java.

Curated Spring Boot resources including a tutorial series, Dockerizing a Spring Boot app, Spring Authorization Server, and the MapStruct DTO mapper.