Java Programming Chapter 4: Functions and Strings

Chapter 4: Mathematical Functions, Characters, and Strings

• Chapter 4 focuses on mathematical functions, characters, and strings in Java programming.
• Motivations for this chapter often involve computing areas or solving location-based problems, like figuring out the area enclosed by multiple cities based on GPS data.
• Objectives include using mathematical methods provided in the Math class, representing characters (char type), encoding characters (ASCII, Unicode), using escape sequences for special characters, casting between numeric and character types, comparing characters, working with String objects, and performing various string operations including concatenation, substring extraction, and character searching.

Mathematical Functions

• Java's Math class provides numerous methods to perform common mathematical operations.

The Math Class

• Contains pre-defined constants: PI and E.
• Offers various methods for trigonometric calculations (sin, cos, tan, acos, asin, atan), exponential functions (exp, log, log10, pow, sqrt), rounding functions (ceil, floor, rint, round), and values generation (min, max, abs, random).

Trigonometric Methods

• These methods in the Math class calculate trigonometric functions, such as sine, cosine, tangent, and their inverses.
• Examples are provided to demonstrate how these methods work.

Exponent Methods

• The Math class includes methods for calculating exponential functions.

Rounding Methods

• The methods allow rounding numbers to the nearest integer.

min, max, abs, and random Methods

• These methods provide functions for determining minimum and maximum values, absolute value, and random values.

Case Study: Computing Angles of a Triangle

• The case study involves writing a program to calculate the internal angles of a triangle based on the given x-y coordinates of its corner points.

Character Data Type

• Java uses Unicode to represent characters

Unicode Format

• Unicode is a 16-bit encoding scheme, crucial for handling diverse languages and characters.
• It takes two bytes and utilizes hexadecimal representations.

ASCII Code for Common Characters

• ASCII is a subset of Unicode containing commonly used characters. It defines the code values (in decimal) for these characters.

Escape Sequences for Special Characters

• Escape sequences are used to represent special characters like tab, linefeed, formfeed etc. in strings.

Appendix B: ASCII Character Set

• A table displaying ASCII codes for commonly used characters.

Casting between char and Numeric Types

• Demonstrates converting a character to an integer or vice-versa using casting.

Comparing and Testing Characters

• Methods for comparing character conditions like being upper-case, lower-case, or a digit.

Methods in the Character Class

• Methods describe the conditions of a character (if it is a digit, letter, or whether it is in uppercase or lowercase etc.)

The String Type

• Java represents strings of characters using the String class
• Strings are reference types, not primitive types.
• Concatenation, assigning, and simple string operations are discussed.

Simple Methods for String Objects

• Methods for working with Strings like getting length, finding a specific character at an index, creating new strings in upper-case/lower-case or trimmed etc.

Simple Methods for String Objects

• These methods need to be called on a specific string instance.

Getting String Length

• Illustrates how to retrieve the length of a string.

Getting Characters from a String

• Demonstrates how to locate and retrieve specific characters within a string.

Converting Strings

• Explains converting strings into upper- or lower-case, and trimming the string.

String Concatenation

• Shows different ways to combine or join multiple strings together using the plus or dot-concat functions

Reading a String from the Console

• Explains how to receive and work with strings entered by the user.

Reading a Character from the Console

• Explains how to read and process characters from the console.

Comparing Strings

• Illustrates comparison methods for strings

Obtaining Substrings

• Explains how to extract parts of a string.

Finding a Character or a Substring in a String

• Demonstrates functions for finding characters and substrings.

Finding a Character or a Substring in a String

• Shows different methods to find a character or a substring(string part) within a string.

Conversion between Strings and Numbers

• Illustrates how to transform strings to numerical values.

Problem: Guessing Birthday

• Describes a program that involves guessing a birthday.

Mathematics Basis for the Game

• Explains the mathematical foundations for determining birth dates (using binary conversion in base-two number system).

Case Study: Converting a Hexadecimal Digit to a Decimal Value

Describes a program that converts hexadecimal digits to their decimal equivalents

Case Study: Revising the Lottery Program Using Strings

• Details a revised lottery program to show the use of strings in programming.

Formatting Output

• Explains the function that generates formatted output.

Frequently-Used Specifiers

• Discusses common format specifiers in output formatting

FormatDemo

• Case study involving formatted table display using printf.