Placement Notes - Page 4

File System versus DBMS

The file based approach fails on redundancy, inconsistency, isolation, atomicity, concurrency, security and integrity. Each failure maps to one specif...

DBMS

What a DBMS Is and Why It Exists

A DBMS is the software layer between users and stored data. It exists to give many users controlled, concurrent, recoverable and consistent access to...

Java

PreparedStatement and SQL Injection Prevention in Java

Concatenating input into SQL lets a caller rewrite your query. Bound parameters make that structurally impossible.

Java

Garbage Collection in Java

The collector reclaims objects that can no longer be reached. Understanding reachability explains both leaks and pauses.

Java

JVM Architecture in Java

The class loader, the runtime data areas and the execution engine, and how a class file becomes running machine code.

Java

Race Conditions and Deadlocks in Java

The two failures that define concurrency: results that depend on timing, and threads that wait for each other forever.

Java

Synchronization in Java: synchronized and volatile

synchronized gives mutual exclusion and visibility. volatile gives visibility only, and knowing the difference prevents most concurrency bugs.

Java

Type Erasure in Java

Generic type information exists only at compile time. Knowing what the compiler removes explains every generics restriction.

Java

How HashMap Works Internally in Java

Buckets, hashing, collisions and resizing. Understanding the mechanism explains the performance and every rule about keys.

Java

List in Java: ArrayList, LinkedList, Vector and Stack

A List keeps insertion order and allows duplicates. ArrayList is the default; LinkedList wins only at the ends.

Java

Exceptions in Java: Hierarchy and Types

Errors, checked exceptions and unchecked exceptions sit in one hierarchy, and knowing which is which decides how you should react.

Java

Wrapper Classes, Autoboxing and Unboxing in Java

Wrapper classes turn primitives into objects so they can be used with generics and collections, and the conversion is automatic but not free.