S-Line Filter: Edit Database

Set JAVA_HOME and JDK Path in Windows Environment Variables

What Will Be the Output? 🤔 | Java 8 Stream API Filter | Java Interview Question #javainterview

System Design: Building a Bulletproof Payment Gateway! 🚀 Basic payment setups fail during network timeouts. To block catastrophic duplicate charges, enforce client-generated idempotency keys (UUIDs). The server saves this key first; if a duplicate request arrives, it immediately returns the cached result instead of re-charging the buyer. Never overwrite database rows to update payment statuses. Instead, implement an immutable ledger where every state change—authorized, captured, or refunded—cre