This glossary defines common terms used in our class. Most are split up by the week they are introduced, though you can skip to course-specific terms for acronyms and words that are about our class itself (rather than computer science concepts).

This glossary is a new experimental resource! We’d love to hear from you with questions, suggestions, or concerns. Post on Ed!

Week 1: Java Basics; Printing, Strings, and Variables¶

• bug: an error in a program
• class*: a file in Java where code is written
  • Note: all code you write in CSE 121 goes into one class
• class comment: a comment that explains a program and its general functionality
• comment: text in a code file that does not affect the behavior of a program
• compiler: a program that translates a programmer's instructions into a form that is more usable by a computer
• console: the place where a program's printed output appears
• debugging: the process of finding and fixing bugs
• executes/runs: when a computer reads a set of instructions written in code and performs them
• hardcode: the practice of placing fixed, unchangeable values directly into code that cannot be modified without modifying the program
• header comment: a comment at the top of a program that includes your name, the date you wrote the program, the class, the assignment, and your TA's name.
• print: display text to the console
• String: represents a collection of letters, digits, or other characters that are strung together
• whitespace: a term to describe characters that are 'invisible' on a screen, such as spaces, tabs, and new lines

Week 2: Data Types and Expressions; String Methods, char, and Variables¶

Data Types, Expressions, Operators¶

• boolean: a data type that represents either true or false
• char: a data type that represents a single character
• double: a data type that represents decimal numbers
• expression: a combination of values and operators that evaluates to a single value
• int: a data type that represents whole numbers
• logical operators: a symbol used to evaluate an expression to true or false (ex &&, ||, !)
• modulo (mod): an operation that finds the remainder of division (%)
• operator: a symbol that performs an operation on a value or variable (ex +, /, %, &&)
• PMMDAS (a simplified order of operations):
  • P - parenthesis
  • MMD - modulo, multiplication, or division, whichever comes first (left to right)
  • AS - addition or subtraction, whichever comes first (left to right)
• precedence: the order in which subexpressions of an expression are evaluated
• relational operators: a symbol used to compare two values and evaluate an expression to either true or false (ex ==, <, >=)
• subexpression: a portion of an expression that can be evaluated independently
• type: the kind of data specified for a value (ex: int, double, String)
  

Variables, Strings, Debugging¶

• assignment: a way to assign a value to a variable
• case-sensitive: distinguishes between uppercase and lowercase letters
• case-insensitive: does not distinguish between uppercase and lowercase letters
• declaration: a way to define a variable with a name and a data type
• index (pertaining to a String): the numerical position of a character in a String
• initialization: a way to store a value into a variable for the first time
• passing in: referring to the argument passed into the parentheses
• primitive: a type that is directly built into Java that always begin as a lowercase letter (ex int, boolean, char, double)
• substring: a portion of characters in a String, defined by a specific starting and ending position
• variable: gives a name to a specific value
• zero-based indexing: the first character in a String is assigned an index of 0 (not 1)

Week 3: for Loops and Nested for Loops; the Random Class¶

for Loops and Nested for Loops¶

• block: the code between two curly braces
• fenceposting: a programming technique used to handle scenarios where the first or last iteration of a loop requires special handling, such as avoiding extra characters or operations. Similar to building a fence with wires separated by posts, we want the fence to start and end with a post to avoid having an extra dangling wire at the end.
  • Let's say we want to print "p-i-c-k-l-e-b-a-l-l" To prevent printing “-p-i-c-k-l-e-b-a-l-l”, we can use fenceposting. First, print out the p. Next, starting at the second character in the String, print a dash and the character, one after the other, for every character in the String.

          
            String word = "pickleball";
            System.out.print(word.charAt(0));
    
            for (int i = 1; i < word.length(); i++) {
              char letter = word.charAt(i);
              System.out.print("-" + letter);
            }
          
        

• for loop: a programming construct that repeats lines of code a set number of times
• infinite loop: a loop that does not stop because the condition required for it to end is never met
• iterate: the act of repeating a process or set of steps until a condition is met, often within a loop
• iteration: a single instance of a repeated process
• nested for loop: a for loop placed inside another for loop; used when we need to repeat a task (inner loop) multiple times within another repetition (outer loop)
• scope: the ability for different variables to be accessed, altered, and utilized within a particular part of a program; variables are typically only in scope within the curly braces that they were created inside
• String traversal: the process of accessing and processing each character in a String one by one

Random Class¶

• object*: a complex value that is typically created with the new keyword (in contrast to simple literal values) (ex Random)
• pseudorandom numbers: a sequence of numbers that appear random, but are actually generated by mathematical formulas and algorithms
• pseudorandom number generator: a computer algorithm that generates pseudorandom numbers
• seed: a starting value used within the initialization of a pseudorandom number generator

Week 4: Methods, Parameters, Returns¶

• calling: a way to execute a method
• class constant: a variable whose value cannot be changed after assignment
• method: a block of code that allows us to define our own commands and compartmentalize our code
• method body: the block of code enclosed within two curly braces of a method
• method comment: a high-level comment that describes a method
  • See the Commenting Guide for more information!
• parameter: the input that a method can receive and use throughout its body; parameters appear in a specific order and have a type
• return: the process of sending a value from a method back to the caller using a return statement
• return type: the type of value that a method is expected to return, as specified in its definition (ex int, double, String)
• void: a type that represents nothing; a method with a void return type returns nothing

Week 5: Conditionals¶

• boolean zen: the act of directly comparing a boolean value equal to true or false within a conditional, which is improper code quality
  • See the Code Quality Guide for more information!
• conditional: a control structure that allows a program to conditionally execute a block of code based on whether a specific condition is true or false
• if statement: a control structure that executes a block of code only if a specified condition evaluates to true
• else if block: a control structure that is an optional part of an if statement; it provides an additional condition to check if the previous condition evaluated to false
• else block: a control structure that is a final, optional part of an if statement that executes a block of code if none of the preceding conditions were true

Week 6: while Loops; User Input (Scanner); Boolean Zen¶

• definite loop: a loop where the number of iterations is known (traditionally a for loop)
• indefinite loop: a loop where the number of iterations is unknown and runs until a certain condition is met (ex: while loops)
• Scanner: an object that is used to read user input
• token: a unit comprised of one or more non-whitespace characters
• while loop: a programming construct that repeats lines of code until a certain condition is met

Week 7: Arrays¶

• array: a data structure of a fixed length that can store multiple values of the same data type
• array traversal: a programming pattern that allows us to examine each element of an array individually using a loop
• data structure: a structured way of storing and manipulating data to enable efficient access
• element: an individual value in an array, referred to by its index
• index (array): the numerical position of an element in an array

Week 8: Reference Semantics; 2D Arrays¶

• null: a Java keyword that represents an absence of a reference
• reference: a value that points to where an object is stored in the computer's memory
• reference semantics: governs object types; when copies are made, a reference to the underlying object is copied
• value semantics: governs primitive types; when copies are made, the underlying value is copied
• 2D (two-dimensional) array: an array of arrays, where each element of the outer array is an array

Course Specific Terms¶

• Pre-Class Materials/Work (PCM/W): Ungraded but highly encouraged short readings. Brief introduction to the new topics that will be covered in lecture; as such, they are due before every lecture.
• Post-Section Work (PSW): Short Google form submitted before midnight on the day of section, as problems within will typically be walked through during section. If enough are satisfactorily completed based on effort, an extra resubmission will be awarded.
• Introductory Programming Lab (IPL): CSE 12x's TA office hours, located in Mary Gates Hall (MGH) 334. Staffed for most of the afternoon and early evening on weekdays, as well as occasional weekends. Hours vary quarter to quarter. View this quarter's schedule.
• ESN Grading: The three grade buckets we use to categorize graded work, with E for Excellent, S for Satisfactory, and N for Not yet. Evaluations based on the skills required to understand and apply the concepts, as we are not necessarily looking for “perfect” code.
• Resubmissions (Resub): An opportunity to revise and resubmit either a programming assignment or a creative project, offered once per week.
• Creative Projects (Cx): Medium to longer semi-guided assignments that allow exploration of programming skills, as well as incorporating more freedom in extension implementations. Assigned a single ESN grade (based on the rubric) and are typically due on Tuesday by 11:59pm.
• Programming Assignments (Px): Longer assignments to assess understanding of class concepts, occasionally incorporating more elements and going further in-depth. Assigned four ESN grades (based on the rubric) and are typically due on Tuesday by 11:59pm.
• Code Quality Guide: Guide to writing quality code, as well as our grading standards for code quality.
• Commenting Guide: Guide to writing quality comments, as well as our grading standards for comments.
• Spec (Specification): Instructions that tell you what the program should do. Will often contain guidance, implementation guidelines, and tips!

Footnotes¶

* This is a topic that is not covered deeply in CSE 121. However, you’ll revisit this idea in-depth in CSE 122 & 123.

Acknowledgements¶

This iteration of the glossary was developed by Hannah Swoffer, Maitreyi Parakh, and Sushma Shankar. This is based on a prior glossary written by Hannah Swoffer and Trey Adams.