Java Notes

Java

A test double stands in for a real dependency so a unit can be tested in isolation, quickly and predictably.

Java

A unit test runs a small piece of code with known input and asserts the result, automatically and repeatedly.

Java

A transaction makes several statements succeed or fail together, and batching turns many round trips into one.

Java

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

Java

JDBC is the standard API for talking to a relational database from Java: a connection, a statement, and a result set.

Java

Since Java 11 the platform includes a modern HTTP client with synchronous and asynchronous requests and HTTP/2 support.

Java

Addresses, sockets and streams. Underneath every network library in Java is a socket carrying bytes.

Java

What changed in each release since Java 8, which old habits it replaces, and what to reach for in new code today.

Java

An immutable object cannot change after construction, which removes whole categories of bug at the cost of a little copying.

Java

A sealed type names exactly which types may extend it, which lets the compiler check that a pattern switch covers every case.

Java

Modules add a boundary above packages: a module declares what it needs and what it exposes, and everything else stays private.

Java

A dynamic proxy implements an interface at runtime and routes every call through one handler, which is how cross cutting behaviour is added.