chapter 3 - syntax + errors + debugging

Size

Programming languages have small vocabularies compared to natural languages.

Rigidity

In a programming language, one must get the syntax absolutely correct.

Literalness

Computers follow instructions in a very literal manner.

Vocabulary of a language

The set of words and phrases used in a programming language. An example of an item in the vocabulary of Java is 'class'.

Syntax rule in Java

A guideline that defines the structure of statements in Java. An example is the requirement that every statement must end with a semicolon.

Expression (x + y) * z

This expression means to first add the values of x and y, and then multiply the result by z.

Differences between programming languages and natural languages

1. Programming languages have strict syntax rules, while natural languages are more flexible. 2. Programming languages are designed for machine understanding, whereas natural languages are for human communication.

Primitive data types in Java

These include numbers (both integer and floating-point), characters, and Booleans.

Objects in Java

Instances of classes that can be manipulated and sent messages.

Concatenation operator

An operator used to combine strings in Java.

Numeric data types

Data types in Java that represent numbers, including int and double.

int data type

A numeric data type in Java that uses 4 bytes of storage and has a range from -2,147,483,648 to 2,147,483,647.

double data type

A numeric data type in Java that uses 8 bytes of storage and has a range from -1.7976931348623157E+308 to 1.7976931348623157E+308.

short data type

A numeric data type in Java that uses 2 bytes for small integers.

long data type

A numeric data type in Java that uses 4 bytes for large integers.

byte data type

A numeric data type in Java that uses 1 byte for very small integers.

float data type

A numeric data type in Java that uses 4 bytes for smaller, less precise floating-point numbers.

Literals

Items in a program whose values do not change, restricted to primitive data types and strings.

Example of numeric literals

Examples include the numbers 5.0 and 9.0, and the string 'Enter degrees Fahrenheit: '.

Storage requirements for int

4 bytes.

Storage requirements for double

8 bytes.

Numeric calculations

A central part of most programs, often following the format: input numeric data, perform calculations, output numeric results.

Temperature conversion program

An example program that adheres to the format of manipulating numeric data types.

Range of int

-2,147,483,648 to 2,147,483,647.

Range of double

-1.7976931348623157E+308 to 1.7976931348623157E+308.

Java's syntax for primitive data types

Involves combining them in expressions using operators like addition and multiplication.

Java's syntax for objects

Involves sending messages to objects.

Instantiation of objects

Objects must be instantiated before use, unlike primitive data types.

Examples of numeric data types

int and double are examples of numeric data types in Java.

Numeric literal

A representation of a number in code.

Integer

A whole number without a fractional component.

Negative integer

An integer that is less than zero.

Floating-point number

A number that has a decimal point.

Exponential notation

A way to express numbers as a decimal followed by a power of 10.

Scientific notation

Another term for exponential notation.

Variable

An item whose value can change during the execution of a program.

Variable declaration statement

A statement that specifies the type of a variable before it is used.

Constant

A variable whose value cannot change after it is initialized.

Final keyword

A keyword used to declare a constant in Java.

String literal

A sequence of characters enclosed in double quotes.

Scanner object

An object used to read input from various sources, including keyboard input.

Instantiation

The process of creating an instance of a class.

Data type

A classification that specifies which type of value a variable can hold.

Double

A data type that can hold floating-point numbers with double precision.

Comment

A piece of text in the code that is ignored by the compiler.

Multiline comment

A comment that includes all text between an opening /* and a closing */.

Floating-point notation

A representation of a number that includes a decimal point.

Variable type

The specific kind of data that a variable can hold.

Variable assignment

The process of setting a variable to a specific value.

Variable name

The identifier used to reference a variable in code.

End-of-line comment

A comment that appears on the same line as a statement, typically used for brief explanations.

Run-time errors

Errors that occur when an illegal operation is attempted during program execution, such as dividing by zero.

Logic errors

Errors that occur when the program does not produce the expected outcome due to incorrect logic.

Purpose of comments

To make a program more readable and easier to maintain.

Variable declaration comments

Comments that explain the purpose of a variable when it is declared.

Major segment comments

Brief comments that explain the purpose of major segments of code.

Complex section comments

Comments that explain the workings of complex or tricky sections of code.

Self-documenting programs

Programs that are written in a way that their code structure and symbols convey meaning without needing excessive comments.

Over-commenting

Including too many comments in a program, which can become burdensome to maintain.

Under-commenting

Including too few comments in a program, making it difficult for others to understand.

Compiler error messages

Messages printed by the compiler when it detects a syntax error.

Cryptic error messages

Error messages that are difficult to understand, often encountered during compilation or execution.

Misleading comments

Comments that restate the obvious or do not add value to the understanding of the code.

Commenting best practices

Guidelines for writing effective comments that enhance code readability.

Code readability

The ease with which a programmer can read and understand code.

Maintaining comments

The process of updating comments to ensure they remain relevant and accurate as code changes.

Error types

The three types of errors in programming: syntax errors, run-time errors, and logic errors.

Compiler

A program that translates source code into byte code, detecting syntax errors in the process.

ArithmeticException

An exception thrown by the Java Virtual Machine (JVM) when an illegal arithmetic operation occurs, such as division by zero.

Case-Sensitivity

A characteristic of programming languages where identifiers are distinguished based on the use of uppercase and lowercase letters.

JVM

Java Virtual Machine, an engine that provides a runtime environment to drive Java applications.

Scanner

A class in Java used to obtain input of primitive types and strings from various sources, including user input.

Null Pointer Exception

An error that occurs when a message is sent to a variable that has not been instantiated.

No Such Method Error

A runtime error that occurs when a method is misspelled, such as 'Main' instead of 'main'.

Test Data

Data used to test a program to verify that it produces the expected output.

Infinity

A value that represents a number that falls outside the range of a double in Java.

Java Case Sensitivity

The property of Java that distinguishes between uppercase and lowercase letters, making 'Main' and 'main' different.

Arithmetic Error

An error that occurs during arithmetic operations, such as division by zero.

Desk Checking

The process of rereading code carefully after writing it to reduce logic errors.

Compile-time Error

An error that occurs when the code is compiled, preventing the program from running.

Debugging

The process of identifying and removing errors or bugs from a program.

Bug

A term used to refer to a logic error in a program.

Terminal Window

The interface where output from a program is displayed.

User Input

Data provided by the user that is processed by the program.

Debugging Statements

Code inserted into a program to help identify and locate errors during execution.

Scanner Class

A class in Java used to obtain input from the user.