Spring Boot

Controller testing checks that REST endpoints return the right status codes and JSON without starting a server or opening a browser. It is used to verify URL mapping, request-body conversion and response handling quickly and automatically. Spring’s MockMvc sends fake HTTP requests straight into the controller and lets you assert on the response. Only the […]

Mockito is a Java library that creates fake (mock) objects so a class can be tested on its own. It is used to isolate business logic: the service is tested without a real database or repository. A mock returns whatever you tell it to, so tests are fast, repeatable and need no MySQL. You can

Unit testing is a software testing technique used to verify individual components of an application independently from the rest of the system. In Spring Boot, JUnit 5 is commonly used to write and execute test cases, while Mockito is used to create mock objects for dependencies such as repositories. For example, a StudentService class may

DatabaseMetaData is a JDBC interface used to obtain information about the database, JDBC driver, tables, columns, and supported database features. It is obtained from a Connection object using the getMetaData() method. Using DatabaseMetaData, a Java program can dynamically inspect database information without directly querying system tables. This is useful for database administration, debugging, database migration

A transaction groups several database operations into one unit of work, so they either all succeed or none of them take effect. If every step succeeds, the transaction is committed and the changes become permanent; if any step fails, it is rolled back and the database returns to its earlier state. In Spring Boot you

A cron expression is a short text pattern that tells Spring exactly when a task should run, such as “every day at 8:30 AM” or “every Monday at 9:00 AM”. Unlike fixed rate and fixed delay, which repeat after an interval, cron ties execution to clock and calendar times. You use it with @Scheduled(cron =

Fixed-rate and fixed-delay are two ways to repeat a background task at a regular interval with @Scheduled. Fixed rate counts the interval from the start of the previous run, so the rhythm stays steady. Fixed delay counts the interval from the end of the previous run, so there is always a pause between runs. Choosing

Scheduled processing lets a Spring Boot application run a method automatically at fixed times or intervals, without any user request. You enable it with @EnableScheduling and mark a method with @Scheduled, and Spring runs it on a background thread. It is used for daily reports, data cleanup, sending reminders, syncing with other systems, and cache

PDF export converts application data into a fixed-layout document that looks the same on every device and prints cleanly.In Spring Boot, a PDF library (here OpenPDF) builds the document in memory as a byte[], and the controller returns it with the application/pdf content type.Unlike CSV or Excel, a PDF is meant for reading and printing,

Export means converting database records into a downloadable file, so users can open, share, or analyze data outside the application. CSV is a plain-text format (comma-separated values) that any tool can open, while Excel (.xlsx) supports styling, formulas, and formatted dates. In Spring Boot, the service builds the file in memory as a byte[] and