Cheat Sheet
Hello, World.
Editing, compiling, and executing.
Built-in data types.
Declaration and assignment statements.
Integers.
Floating-point numbers.
Booleans.
Comparison operators.
Parsing command-line arguments.
Math library.
The full java.lang.Math API.
Type conversion.
If and if-else statements.
Nested if-else statement.
While and for loops.
Break statement.
Do-while loop.
Switch statement.
Arrays.
Compile-time initialization.
Typical array-processing code.
Two-dimensional arrays.
Compile-time initialization.
Ragged arrays.
Functions.
Libraries of functions.
Our standard random library.
Our standard statistics library.
Using an object.
Creating an object.
Instance variables.
Constructors.
Instance methods.
Classes.
Object-oriented libraries.
-->
Java's String data type.
The full java.lang.String API.
Note: the java.lang.StringBuilder API is similar, but StringBuilder supports some operations more efficiently than String (notably, string concatenation) and some operations less efficiently (notably, substring extraction).
Compile-time and run-time errors.
Here's a list of errors compiled by Mordechai Ben-Ari. It includes a list of common error message and typical mistakes that give rise to them.