Java 101 Build Season Code Standards. OCT

Transcription

1 Java 101 Build Season Code Standards OCT jaander8@ncsu.edu

2 Keep in Mind: A program is read from top to bottom when compiled and run Any capitalization matters Statements end with a semicolon (;) Match up your closed brackets

3 Variables & Their Declarations: Int - An Integer (no decimal places) declared as int Ex: int a = 7; Double - A number with decimal places declared as double Ex: double x = 8.02; Char - A character/letter, declared as char Ex: char b = c ; String - a connection of characters, can be words, declared as String Ex: String name = Jill Boolean - a true or false expression, declared as boolean Ex: boolean bool = true;

4 Anatomy of A Declaration int numval = 20; Type of Variable Declared Name (You choose) The value of the variable String first_name = Jillian ;

5 Classes & Methods: Class: Class name MUST match the filename exactly in order for the file to compile With the exception of any imports or comments; class is the first line of code EX: TestFile.java public class TestFile { } Method: Inside the class of a program Can be multiple and there are multiple types First there exists the main method EX: (Main): Public static void main(string[] Args] { } EX: public static void Methodname() { }

6 Anatomy of Classes/Methods public class Test { public static void main(string[] Args){ Int x = 4; squared(x); public static int squared(int a){ int result; } } result = a * a; return result; Functions in Main Method method name Variable type of method, will return an int Class and class name (matches filename) Main method Method

7 Comments and Formatting Why Use Comments: Allow anyone to understand the code and rationalize reasoning behind chosen functions and declarations. Single Line Comment: to explain a variable or give a short explanation Ex: //this is a single line Multiple Line Comment: to describe a process, purpose, or emphasize the point of the function Ex: /** this is a multiple * line comment */

8 Variable/Class Name Etiquette camelcase: Used for variables First word is lowercase, following have a capital first letter Must be fairly simple to understand and know the relation input, joystickleft, redapple Magic Numbers: Magic numbers are unfortunate for anyone looking over the code or new to programming. Solution = constants - easy to change and understand EX: MAX_NUMBER = 10 for(int i=0; i<max_number; i++){

9 Operators: Addition Int sum; sum = x + 4 Subtraction Int difference; difference = x - 4 Multiplication Int product; product = x * 3 Division Int divided; divided = x/4 Modulo (remainder) Int mod; mod = x % 2 Powers Int cubed; cubed = Math.pow(x,3);

10 System.out.println( ) ; Print out something if(situation){ DO THIS If, Else Command } Do{ ACTION Do, While Command } while (SITUATION)

11 When In Doubt: FIRST Tutorials WPILIB API Github Code Chief Delphi Java API Handy Java Reference Textbook(s) Last resort ofc

12 Activity: You will be put into two teams, each will work on and write out the following two programs, using the online compiler to help. We will check as a class and write sections of the code out on the board. Figures.java ColorReader.java

13 Figures.java **Note that to create a backslash \ in a system print, you must use an escape sequence. Backslash: \\ Create a program that will print the text image to the left, using System.out.println( ); Decompose the file into the following methods executed in a method called drawfigures(); drawhexagon(); drawblankline(); drawbowl(); drawdashedline(); drawstopsign(); drawtrapezoid();

14 ColorReader.java - use online coder **Before the class, import the package needed for a Scanner: import java.util.*; Objective: Write a piece of code that reads a shorthand text description of a color and prints the full color name. Accepted colors are: B for blue, G for green, and R for red. If a user enters something other than B, G, or R the program should print an error message. The program should be case insensitive so b = B and vice versa. Ex: What color do you want? B You have chosen Blue. What color do you want? Bork Unknown color: Bork Expressions: Uses if, else statements, a Scanner, and global variables* *global variables are declared in the class before the main method as: public static DT name; Or public static final DT name;

15 Shooter Plans (Draft)

16 thanks! ANY