Intermediate 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

A thread moves through six states, and knowing which one it is in is the first step in diagnosing any hang.

Java

A thread is an independent path of execution inside one process, and Java gives you several ways to start one.

Java

Every unbuffered read is a system call. Buffering turns thousands of them into a handful, and it is the single largest I/O win available.

Java

InputStream and OutputStream carry raw bytes; Reader and Writer carry characters. Choosing wrongly corrupts data.

Java

Path names a location and Files performs the operations. Together they replaced the older File class for almost every purpose.