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In Kotlin, you create a class with the class keyword, and you create an object instance by calling the class constructor. class Person { var name: String = "Unknown" var age: Int = 0 } fun main() { val person = Person() person.name = "Alice" person.age = 25 println("${person.name} is ${person.age} years old") } Output: […]
A compiled Java .class file starts with a fixed header (0xCAFEBABE), followed by a pair of numbers: minor_version and major_version. The pair (commonly written as major.minor, e.g., 52.0) identifies which Java platform level the bytecode targets. The JVM uses this to decide whether it can load the class. If the class was compiled for a […]
Virtual threads are one of the most exciting additions to modern Java. They make it much easier to write highly concurrent applications without the complexity of managing large thread pools, callbacks, or reactive pipelines. If you build applications with Spring Boot, virtual threads can help your app handle many more concurrent tasks with simpler code. […]
ResultSetMetaData lets you inspect the shape of a SQL query result at runtime — for example: how many columns were returned each column’s name and label its SQL type table/schema info if available whether values can be null, are auto-incremented, etc. Basic usage package org.kodejava.jdbc; import java.sql.*; public class MetaDataExample { public static void main(String[] […]
You use java.sql.DatabaseMetaData by: Opening a Connection Calling conn.getMetaData() Querying catalogs/schemas/tables/columns/keys/indexes via the DatabaseMetaData “getXxx” methods (they mostly return ResultSets) Reading those result sets like normal query results Below are the most common inspection tasks and the JDBC calls that power them. 1) Get the DatabaseMetaData package org.kodejava.jdbc; import java.sql.Connection; import java.sql.DatabaseMetaData; import java.sql.Dr...
In JDBC, “database timeouts” can mean a few different things, and you handle each at a different layer. The most practical approach is to set timeouts deliberately and then catch the right exception types so you can decide whether to retry, fail fast, or surface a user-friendly error. 1) Connection timeout (can’t connect / handshake […]
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