Concepts starting with J
46 concepts, each with a plain-language explanation, examples and diagrams. Pick a letter or open a concept.
- Jacobian Matrix — Backpropagation calculates the gradient of a loss with respect to network weights for an example.
- Jar Files and Packaging Programs — A resource is data a program uses that is not code, such as images, sounds, and text; the user normally does not need to know…
- Java and Networked Applications — The Internet is a worldwide network containing millions of connected computers.
- Java and the Internet — Java's networking support should be understood as one advantage among others.
- Java Arrays Basics — The standard array-processing methods are static methods defined in the Arrays class, which is in the java.util package.
- Java bytecode — Just-in-time compilation translates Java bytecode into native machine language during program execution.
- Java Classes and Instance Variables — A Java record is an object that belongs to a special kind of class called a record class.
- Java Classes and Interfaces — Packages are named containers for related Java classes and interfaces.
- Java Collections Framework: ArrayList and Collections.sort — Sorting WordData objects by frequency in descending order means placing the record with the highest count first.
- Java Color Class — RGB describes a color with three numbers giving the levels of red, green, and blue, and Java creates such a color with the…
- Java Compilation and Java Bytecode — The JVM is a virtual computer, not a physical machine.
- Java Constructors and Object Initialization — A canonical constructor takes parameters to initialize an object's fields, and it can be customized with additional code.
- Java Control Flow with if-else Statements — A switch statement chooses one block of code based on the value of an integer variable, and each case label is associated with a…
- Java Data Types — Arithmetic expressions depend on both the operator and the types of the operands.
- Java Development Environments — Packages are named containers for related Java classes and interfaces.
- Java Development with Eclipse IDE — Download Eclipse IDE for Java Developers from the official Eclipse packages page.
- Java Event Handling — Java has three complete GUI-toolkit families discussed here: AWT, Swing, and JavaFX.
- Java Events and Event Listeners — A custom component is written by subclassing an existing Java component class, which lets you keep inherited behavior and change…
- Java Expressions and Operators — When several operators appear in one expression without parentheses, precedence decides which operator is evaluated first, using…
- Java File Dialogs and Saving User Work — ImageIO is the Java class that moves images between a running program and files, in both directions
- Java Frames and Windows — A custom dialog box is built as a subclass of JDialog, and it is a separate window much like a frame.
- Java GUI Components — User interactions with GUI components generate events.
- Java If and Else Statements — The dangling else problem occurs when nested if statements are interpreted differently by the compiler than the programmer…
- Java Import Directives — Packages are named containers for related Java classes and interfaces.
- Java Methods and Arguments — A method reference such as Math::sqrt is a shorthand that names an existing method without calling it at that point.
- Java Network Support — Java's early Internet identity was strongly connected to applets.
- Java Numeric Types — Assignment is an operator whose value is the value assigned to the left-hand variable.
- Java Packages — Declare a package at the beginning of the Java source file with package package_name;.
- Java Packages and Import Statements — The GUI version of TextIO is textiogui/TextIO.java, a class that opens a window where TextIO I/O operations are performed.
- Java Program Structure — A Java program is defined within a public class.
- Java Record Classes and Their Components — Declaring a class final means no subclass can exist, so the compiler knows exactly what each method call does and can optimize…
- Java Statements and Expressions — jshell provides a direct command-line way to try Java code.
- Java Swing Components and Layouts — GridLayout arranges components in a grid, and the add-call order determines their positions.
- Java variable declarations — An enum defines a type with a fixed set of named values.
- Java Window Basics with JFrame — The pack() method resizes a window to match the preferred size of its contents, and it works correctly only when every component…
- Java's Standard Packages — A package can contain both classes and other packages, and a package contained in another package is called a subpackage.
- Javadoc Comments — A doc tag is a command inside a Javadoc comment, identified by a name that begins with @.
- JavaScript for Web Visualization — A geospatial application pipeline connects input data, a geocoding API, a database, and a visualization layer.
- Jensen's Inequality — Gradient Descent convergence is analyzed here for convex-Lipschitz functions.
- JOIN Syntax and Fundamentals — Many-to-many relationships require three tables: two entity tables and one junction table that holds foreign keys linking them.
- Joins: Combining Data from Multiple Tables — SQL uses a single equal sign (=) for equality testing in WHERE clauses, not the double equal sign (==) used in Python.
- JSON and XML: Data Formats for Web Services — A web service is a set of services in an application's API that are made available over the web via HTTP.
- JSON Syntax and Structure — XML uses tags and attributes; JSON uses curly braces and key-value pairs to represent the same information.
- JSON: A Lightweight Data Format — An API is an application-to-application contract that publishes rules for accessing services provided by one program for use by…
- Junction Tables and Composite Primary Keys — A junction table with a role attribute stores not just the fact of a relationship, but also the nature of that relationship…
- Junction Tables: Implementing Many-to-Many Relationships — A many-to-many relationship exists when records on both sides can connect to multiple records on the opposite side, unlike…