Glossary
This page will include all of the
Keep in mind that since this course is being released week by week, the video material links for the vocabulary that you have not yet encountered will remain inactive until the corresponding week has been released.
| Term | Definition | Link to content |
| Abstraction | The process of simplifying or hiding complicated implementation details in order to reduce complexity and showing only the functionality. | Problem Solving |
| AND logical operator | The logical AND operator (&&) returns the boolean value true if both operands are true and returns false otherwise. The operands are implicitly converted to type boolean prior to evaluation, and the result is of type boolean. | Primitive Type - boolean |
| API | Application Program Interface is a set of functions that are exposed by a system or programming language in order to allow a developer to write code that interacts with that existing code. | The Scanner Class |
| Argument | An argument is a value passed into a function. This value is then used for operations within the function. We often talk about how many arguments are needed by a specific function. | Example-Robot(Cont.) |
| ASCII | ASCII stands for American Standard Code for Information Interchange. Computers can only understand numbers, so an ASCII code is the numerical representation of characters and symbols such as 'a' or '@'. | Primitive Type - Char |
| assert keyword | assert is a Java keyword used to define an assert statement. An assert statement is used to declare an expected boolean condition in a program. If the program is running with assertions enabled, then the condition is checked at runtime. | Example: Compute Change |
| Assignment | An assignment statement in Java uses the assignment operator (=) to assign the result of an expression to a variable. | The Scanner Class |
| Binary | A number representation system that counts in base-2 rather than base-10 (decimal system). This is used because computers only understand two states 1 or 0. | Introduction to the Binary system |
| Bit | A single binary digit, represented either by a "1" or a "0". All information stored in a computer is made up of individual bits. | Introduction to the Binary system |
| Bitwise operator | A bitwise operator is used to perform bitwise operations on bit patterns or binary numerals that involve the manipulation of individual bits. | Casting |
| Block | A block is a group of zero or more statements between balanced curly braces. | Example-Hello World |
| Boolean primitive type | A Boolean value is one with two choices: true or false, yes or no, 1 or 0. | Primitive Type - boolean |
| break Keyword | Break statement is one of the several control statements Java provide to control the flow of the program. Used to indicate termination of loop or switch case | Switch Basics |
| Byte | A byte is made up of 8 bits. | Memory Sizes |
| Bytecode | An intermediate language that is executed by a runtime program. Java code is compiled to a bytecode before it is interpreted by the Java Virtual Machine. | Programming Languages and Translations |
| Cache | A cache is a temporary storage area. In modern hardware, there are several levels of cache that are used to store data close to the processor for quick retrieval. | Memory Sizes |
| case Keyword | Identifies the various cases in a switch statement | Switch Basics |
| Char literals |
Representation of a character value within the source code of a computer program. e.g char a = 'A'; |
Primitive Type - Char |
| char type | A char is a primitive data type. It stores a 16-bit value. | Primitive Type - Char |
| Class | A class is a template for creating objects. Within a class contains the outline for variables, and methods/functions. | The Software Lifecycle |
| Code block | Refers to the block of code between curly braces | Curly Braces, Block Form |
| Comments | Comments are a section of code that is not compiled or run. They can be used to explain parts of the code, keep track of things remaining to be done, or any other type of documentation. | Program Structure and Other Basics in Java |
| Comparison operator | The result of every comparison is boolean (true or false). | Comparing Strings |
| Compile | When a program compiles, the computer is turning the program into bytecode. In other languages, compiled code is translated into assembly code and then eventually machine code which resembles the binary numbers that a computer understands. | Programming Languages and Translations |
| Concatenate | You can concatenate/combine/join two Java Strings using the + operator. | Example-Robot(Cont.) |
| Conditional Execution | A statement that controls the flow of execution depending on some condition. The boolean expression in a conditional statement that determines which branch is executed. | Selection Basics |
| Console | Console refers to a terminal attached to a minicomputer or mainframe and used to monitor the status of the system. | Example-Hello World |
| Constructor | A constructor is a special method of a class, but instead of being called, the constructor executes when an object is created and initializes an instance of class type. A class can have more than one constructor if the parameters are different. | Example-Robot(Cont.) |
| CPU | The Central Processing Unit contains the logic circuits that perform all the instruction sent by the computer’s programs. It contains an ALU (Arithmetic and Logic Unit) and a Control Unit which then handles the execution of computational instructions and fetches and decodes new instructions. | Problem Solving |
| Dangling else | A dangling else is a problem in code that arises when there are nested if statements and it is not made clear which if statement the else statement corresponds to. | Dangling else |
| Decrement | An decrease/subtraction, especially by a fixed value. | Operator Shortcuts |
| default Keyword | The default statement is where the switch operator jumps to if none of the case labels match the controlling expression. | Switch Basics |
| DeMorgan's Laws | !(a || b) == !a && !b and !(a && b) == !a!|| !b | DeMorgan's Laws |
| Dot operator | A dot operator connects classes and objects to methods. | The Scanner Class |
| Double class | The java.lang.Double class wraps a value of the primitive type double in an object. An object of type Double contains a single field whose type is double. | Wrapper Class |
| double Type | A double is a primitive data type. It stores a 64-bit floating point value. | Example-Wheel |
| Downcasting | Casting is the process of changing a variable to a different data type. When downcasting, you are changing the data type to one that has smaller storage. | Casting |
| Eager Evaluation | Eager evaluation is used by most programming languages, including Java, and it means that when you assign an expression to a variable, the computer calculates the expression and stores the result in the variable. This is the opposite of short-circuit evaluation. | Short-circuit Evaluation |
| Efficiency | The fewer lines of code that are required to complete the algorithm, the more efficient it is. | Tenets of Good Programmers |
| else block | When the condition in the if-statement returns false, the commands in the else block are executed | Selection Basics |
| End-behavior | Behavior of variable as it approaches its bounds. | DeMorgan's Laws |
| Epsilon | Since floating point calculations involve a bit of uncertainty we can try to allow for this by seeing if two numbers are ‘close’ to each other. If you decide – based on error analysis, testing, or a wild guess – that the result should always be within 0.00001 of the expected result then you can change your comparison to this:if ((result - expectedResult) < 0.00001) // This is how you compare. The maximum error value is typically called epsilon. | Example: Compute Change |
| Equality relational operator | The equality operator is ==. It is used to test if two values are equal, and results in a boolean value. | Primitive Type - boolean |
| Escape Sequence | Characters like tab, newline. | Primitive Type - Char |
| Ethical Behavior | Behavior that follows coding ethics. | Ethics of CS and Engineering |
| Ethics | Ethics are an individual's thoughts and beliefs regarding their behavior and how their behavior, in turn, affects those people in the world around them. | Ethics of CS and Engineering |
| Exception | Exceptions are thrown when something goes wrong in either the compiling of the code or running of the code. | Example: Compute Change |
| Exclusive OR (XOR) | True only when one, or the other is true, otherwise false | Boolean Operators |
| Expression | A combination of symbols that represent a value. | Casting |
| Field | A field is a class, interface, or enum with an associated value. | Constructors and Field |
| Floating Point Numbers | Decimal numbers | Real Numbers |
| Floating point type | A float is a primitive data type that stores a 32-bit decimal value. | Primitive Types |
| Greater than relational operator | ">" This operation specifies a "greater than relation between two values. | Primitive Type - boolean |
| Hard Disk | A Hard Disk Drive (HDD) is a magnetic disk in your computer where you can store data. It is permanent memory, and is the slowest access point in your computer’s memory system. | Memory Sizes |
| Hexadecimal | A number representation system that counts in base-16 rather than base-10 (decimal system). To code the numbers 10-15, a hexadecimal system employs the letters A-F. | Other Number Systems |
| IDE | Integrated Development Environment. This type of environment allows an application developer to write code while compiling, debugging and executing it at the same place. It is a program designed to help programmers write code. Most will include minimum tools that highlight keywords, indent new blocks and do some auto-completion of code. | How to Start Writing Code |
| if-block | Commands inside the if-block will execute if the condition in the if-statement return true. | Selection Basics |
| Immutable | Immutable means that once the constructor for an object has completed execution that instance can't be altered. Strings are immutable in Java, where if you modify a String, a whole new memory gets assigned to the String and the old String still occupies memory, just not accessible. | Strings |
| Import | To import something means you are transferring data from one piece of software to another. In Java, import is a keyword that is used to indicate which pre-written classes or packages you are using. | Program Structure and Other Basics in Java |
| Increment | An increase/addition, especially by a fixed value. | Operator Shortcuts |
| Inequality relational operator | "!=" specifies that the relation between two values is not equal. | Primitive Type - boolean |
| Integer class | The java.lang.Integer class wraps a value of the primitive type int in an object. An object of type Integer contains a single field whose type is int. | Wrapper Class |
| Integer Division | The result is rounded down to the nearest Integer. | Operations on Integer Types |
| integral type | An int is a primitive data type. It stores a 32-bit value | Primitive Types |
| JDK | Java development kit. The underlying components used to write Java code. | The Software Lifecycle |
| JRE | Java Runtime Environment. JRE is part of the JDK. This is the component that allows us to run our completed code. | How to Start Writing Code |
| JVM | Java Virtual Machine is the runtime engine of the Java Platform, which allows any program written in Java or other language compiled into Java bytecode to run on any computer that has a native JVM. | Programming Languages and Translations |
| Keyword | Special words reserved by a programming language or by a program. You are not allowed to use keywords as variable names. | Program Structure and Other Basics in Java |
| Legal Behavior | Behavior that is required by the law. This is not the same as Ethical Behavior. | Ethics of CS and Engineering |
| Less than relational operator | "<" This operation specifies a "greater than" relation between two values. | Primitive Type - boolean |
| Library | A library, in this case a library in Java, is where pre-written classes are stored. | The Scanner Class |
| Logical AND operator | True when one, AND other (both) operands are true. False when either of the operands are false | Boolean Operators |
| Logical NOT operator | Reverses the Meaning of operand. | Boolean Operators |
| Logical OR operator | True when one, or other, or both operands are true. Only false when both operands are false | Boolean Operators |
| Main Method | Every Java program must have a main method. This is where the program begins execution. | Example-Hello World |
| Mantissa | The part of a floating-point number that represents the significant digits of that number, and that is multiplied by the base raised to the exponent to give the actual value of the number. eg: in 0.456, 456 * 10^-3, 456 is mantissa. | Real Numbers |
| Math Library | All of the basic math functions beyond the binary operators can be found in java.lang.Math. This class is important because it allows you to do a number of operations, such as finding the absolute value, using log, etc. This is also a static class, which we will learn more about later. | Operations on Real Types |
| Memory address | Hexadecimal address where memory is stored. | Comparing Strings |
| Memory allocation | Memory allocation is the process of setting aside sections of memory in a program to be used to store data. | References |
| Method | A method belongs to a class, and it defines what tasks that class can do. | The Software Lifecycle |
| Method call | How you call a method. | Example-Robot(Cont.) |
| Naming Conventions | A naming convention is the suggested rule for assigning names to your variables and definitions. The preferred naming conventions for Java: Variables/Objects are always in camelCase; Classes are in UpperCamelCase; Constants are in ALL_CAPS. | Formatting |
| new Keyword | "new" is used when to declare a new object through its constructor. | Example-Robot |
| NOT logical operator | "not" is a Boolean operator that returns the opposite of the input. Often is denoted by the ! | Primitive Type - boolean |
| null reference | Literally, "null" means nothing or without value. In programming, it refers to something not having any value attached to it. Null is the default value of all variables until you assign them to something. | References |
| numeric type | A data type that represents a number. | Primitive Types |
| Object | An object is an instance of a class. This means that in order to use the methods of a class, you have to create an object. This object maintains its own state (values for the variables that appear in the class definition for the object), and behaves according to the methods defined within the class. | The Software Lifecycle |
| Octal | A number representation system that counts in base-8 rather than base-10. | Other Number Systems |
| Operator Precedence | Same as order of operations for normal math problems. You can remember the order as Please Excuse My Dear Aunt Sally (Parentheses, exponents, multiplication, division, addition, subtraction). All math operations will follow this order. | Casting |
| OR logical operator | "or" is another Boolean operator like "and" and "not". In this case, it evaluates to True if either of the 2 arguments are True. or is usually denoted by ||, two vertical pipes. | Primitive Type - boolean |
| Overflow | Opposite of underflow, when a number is actually too big for the computer to store in memory. | Overflow and Underflow |
| Parameter Name | The name given to a parameter | Example-Robot(Cont.) |
| Parameter Type | A special kind of variable, used to refer to one of the pieces of data provided as input to a method. | Example-Robot(Cont.) |
| Pass a Parameter | When you call a function, it may require one or more parameters (values appearing in between the parentheses that follow the function name). To provide values to the method, you pass the data, and the function will use that data to complete its tasks. | Example-Robot(Cont.) |
| Peripheral | Any computer device that is not part of the essential computer (the processor, memory, and data paths) but is situated relatively close by. | Memory Sizes |
| Pointer | An object that refers to a specific address in memory, and this can be used to refer to another object. | References |
| Postfix | When the operators are written after their operands. e.g. a++ | Operator Shortcuts |
| Prefix | When the operators are written before their operands. e.g. ++a | Operator Shortcuts |
| Primitive type | A basic data type that is predefined by a programming language. In Java, the eight primitive types are: byte, short, int, long, float, double, boolean, & char. | Primitive Types |
| Promotion | Refer to Upcast | Casting |
| RAM | RAM (random access memory) is the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer’s processor. | Problem Solving |
| Reference type | A data type that refers to an object--any object that is not a primitive type is a reference type. Every instance of a class is a reference, including data types like Strings. | Casting example |
| Relational operator | An operator that tests of defines the relation between two operators. Examples: "==", "!=", ">", "<", ">=", "<=" | Relational Operators |
| return Keyword | Causes the execution to end in that specific method. | Example-Wheel |
| Return Type | Each method can return one value dependent on the data type specified as the return type (int, double, String, void, bool, etc). Note that a method that doesn’t return a value has a void return type. | Example-Robot |
| Scanner | The Scanner class is used to read information from an input stream. This can be the user of the program, or a file. It is imported for use in any Java program. | The Scanner Class |
| Selection Statement | A control statement that allows choosing between two or more execution paths in a program. | Selection Basics |
| Sequential Statement | Statements execute in order that we save them in the program | Selection Basics |
| Short-circuit Evaluation |
For some Boolean operators, the second argument is only checked if the first is true. In the case of the condition statement: if ( false && (whatever)) //returns false Because the first argument is false and the operator "&&" requires both arguments to be true to return true, the (whatever) is not evaluated and the statements returns false. |
Short-circuit Evaluation |
| Shorthands | These are nice ways to save a few keystrokes as we type out our instructions, and are particularly useful if we use long variable names. e.g. *=, += | Operator Shortcuts |
| Sign Bit | The most significant number represents the sign of the number. | Number Representations |
| Software Development Lifecycle | The steps required to develop a piece of Software. | The Software Lifecycle |
| Standard Input | Source of input data for command line programs | The Scanner Class |
| static Keyword | Static is a keyword in Java that is used to describe a certain type of method or variable. When all of the methods and variables of a class are static, you could say that class is a static class. When used with variables, it means that the variable is the same for all instances of that class (i.e., all objects will share one single value). When used with methods, it means you can use that method without creating an object of that class. | Example-Robot |
| String interning | String.intern() can be used to save memory by ensuring that any duplicate Strings use the same memory. If a large number of names is being stored, interning the Strings would cause the name Phil to only be stored once, even if there were multiple Phils. | Comparing Strings |
| String literal | A sequence of characters surrounded by quotation marks that can populate a String Object. | Strings |
| String type | An object that holds a grouping of characters together. | Primitive Type - Char |
| String.charAt() | Returns a char that is at the specified index in the string. | References Continued |
| String.compareTo() | Compares the passed string to the specified object, and returns 1, -1, 0. | String Operations |
| String.equals() | Compares the passed string to the specified object and return a boolean. | String Operations |
| String.indexOf() | Returns the index of the first occurrence of the passed string. | References Continued |
| String.length() | Returns the length of the specified string. | Strings |
| String.substring() | This can be used to to create a substring either from the passed index to the end of the string, or from one index to another. | Strings |
| Style | The way that your code looks on the screen is referred to as the style. | Tenets of Good Programmers |
| Swap | To swap values in variables we need to create a temporary variable to store one of the values before swapping. | Example- Swapper |
| Switch Keyword | A switch statement allows a variable to be tested for equality against a list of values. Each value in this list is called a case, and the variable being switched on is checked for each case | Switch Basics |
| Syntax | The arrangement of words and phrases; code differs for different programming languages. | Example-Hello World |
| System.out.printf() method | A method that prints formatted text on to the system. | Printf and Format |
| Temporary Variable | A variable that is created to store a value temporarily. | Example - Swapper |
| Ternary Operator | condition ? true-value : false-value | Ternary Operators |
| this Keyword | "this" is another keyword in Java that is used by classes and objects to reference themselves. It is handy to use in constructors when the parameter names match the class variable names, or when writing a method that will refer to a second instance of the class in which that method is defined (passed as a parameter). | Example-Robot(Cont.) |
| Threshold | A value for a "minuscule difference" below which the answer is still considered correct. The smaller the value, the more precise we want our calculations to be | Example: Compute Change |
| Truncate | The result of storing data in a location that is not large enough for its size and those some data is lost. | Operations on Integer Types |
| Truth Table | A Truth table show all the possible combination of inputs and then what outputs they all give. | DeMorgan's Laws |
| Typecast | The act of converting data from one type to another. | Casting example |
| Types | Types refer to different ways of storing data and what possible values they can contain. | References |
| Underflow | Opposite of overflow, when a number is actually too small for the computer to store in memory. | Overflow and Underflow |
| Unicode | An encoding standard used to represent characters and symbols. | Primitive Type - Char |
| Upcast | Opposite of downcasting. To upcast a value, you are casting it to a supertype (a data type that can hold a larger amount of data). | Casting |
| Variable name | The name given to a variable. | Example-Wheel |
| Variable type | A variable is a reference to a value stored in memory, which can change over the lifetime of the program. | Example-Wheel |
| void Return Type | Void is a keyword that denotes a method that does not have a return type. Note that a constructor also does not have a return type, however, it does not have "void" in its declaration. A variable cannot be declared as a void type. | Example-Robot |
| Von Neumann Architecture | A computer architecture conceived by mathematician John von Neumann, which forms the core of almost every computer system in use today. | Problem Solving |
| Wildcard symbols | Wildcard character is a single character, such as an asterisk (*), used to represent a number of characters or an empty string. | Printf and Format |
| Wrapper Class | A class that encapsulates, hides or wraps data types from the eight primitive data types | Wrapper Classes |
| XOR logical operator | The xor operator is: ^ It is a bitwise operator that will assess 2-bit values and return 1 if one and only one of the bits is a 1. | Primitive Type - boolean |
| zero-based index | A zero-based index means that the index for a particular array-like structure is zero. This is how arrays and Strings are structured in Java. | Strings |