From fbe0fb471896e55c40d734b082f5e994e6dc775d Mon Sep 17 00:00:00 2001 From: Jake Prather Date: Sun, 30 Jun 2013 12:17:19 -0500 Subject: Added file name param and more. See description. -Fixed some minor issues/details -Can actually compile now (not just a bunch of random snippets) -Added more text & explanation to a few parts --- java.html.markdown | 377 ++++++++++++++++++++++++++++------------------------- 1 file changed, 200 insertions(+), 177 deletions(-) diff --git a/java.html.markdown b/java.html.markdown index 648b98bc..3208971d 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -6,6 +6,8 @@ author: Jake Prather author_url: http://github.com/JakeHP +filename: learnjava.java + --- Java is a general-purpose, concurrent, class-based, object-oriented computer programming language. @@ -19,120 +21,120 @@ Multi-line comments look like this. // Import Packages import java.util.ArrayList; -import package.path.here; // Import all "sub-packages" import java.lang.Math.*; -// Your program's entry point is a function called main -public class Main +// Inside of the learnjava class, is your program's +// starting point. The main method. +public class learnjava { - public static void main (String[] args) throws java.lang.Exception + //main method + public static void main (String[] args) { - //stuff here - } -} - -// Printing, and forcing a new line on next print = println() -System.out.println("Hello World"); -System.out.println("Integer: "+10+"Double: "+3.14+ "Boolean: "+true); -// Printing, without forcing a new line on next print = print() -System.out.print("Hello World"); -System.out.print("Integer: "+10+"Double: "+3.14+ "Boolean: "+true); + +System.out.println("->Printing"); +// Printing, and forcing a new line on next print, use println() +System.out.println("Hello World!"); +System.out.println("Integer: "+10+" Double: "+3.14+ " Boolean: "+true); +// Printing, without forcing a new line on next print, use print() +System.out.print("Hello World - "); +System.out.print("Integer: "+10+" Double: "+3.14+ " Boolean: "+true); /////////////////////////////////////// // Types /////////////////////////////////////// - +System.out.println("\n\n->Types"); // Byte - 8-bit signed two's complement integer // (-128 <= byte <= 127) -byte foo = 100; +byte fooByte = 100; // Short - 16-bit signed two's complement integer // (-32,768 <= short <= 32,767) -short bar = 10000; +short fooShort = 10000; -//Integer - 32-bit signed two's complement integer +// Integer - 32-bit signed two's complement integer // (-2,147,483,648 <= int <= 2,147,483,647) -int foo = 1; +int fooInt = 1; -//Long - 64-bit signed two's complement integer +// Long - 64-bit signed two's complement integer // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807) -long bar = 100000L; +long fooLong = 100000L; // (Java has no unsigned types) -//Float - Single-precision 32-bit IEEE 754 Floating Point -float foo = 234.5f; +// Float - Single-precision 32-bit IEEE 754 Floating Point +float fooFloat = 234.5f; -//Double - Double-precision 64-bit IEEE 754 Floating Point -double bar = 123.4; +// Double - Double-precision 64-bit IEEE 754 Floating Point +double fooDouble = 123.4; -//Boolean - True & False -boolean foo = true; -boolean bar = false; +// Boolean - True & False +boolean fooBoolean = true; +boolean barBoolean = false; -//Char - A single 16-bit Unicode character -char foo = 'A'; +// Char - A single 16-bit Unicode character +char fooChar = 'A'; -//Make a variable a constant +// Make a variable a constant final int HOURS_I_WORK_PER_WEEK = 9001; -//Strings -String foo = "Hello World!"; +// Strings +String fooString = "My String Is Here!"; // \n is an escaped character that starts a new line -String foo = "Hello World!\nLine2!"; -System.out.println(foo); -//Hello World! -//Line2! +String barString = "Printing on a new line?\nNo Problem!"; +System.out.println(fooString); +System.out.println(barString); -//Arrays +// Arrays //The array size must be decided upon declaration //The format for declaring an array is follows: // [] = new []; -int [] array = new int[10]; -String [] array = new String[1]; -boolean [] array = new boolean[100]; +int [] intArray = new int[10]; +String [] stringArray = new String[1]; +boolean [] booleanArray = new boolean[100]; // Indexing an array - Accessing an element -array[0]; +System.out.println("intArray @ 0: "+intArray[0]); // Arrays are mutable; it's just memory! -array[1] = 1; -System.out.println(array[1]); // => 1 -array[1] = 2; -System.out.println(array[1]); // => 2 +intArray[1] = 1; +System.out.println("intArray @ 1: "+intArray[1]); // => 1 +intArray[1] = 2; +System.out.println("intArray @ 1: "+intArray[1]); // => 2 -//Others to check out -//ArrayLists - Like arrays except more functionality is offered, +// Others to check out +// ArrayLists - Like arrays except more functionality is offered, // and the size is mutable -//LinkedLists -//Maps -//HashMaps +// LinkedLists +// Maps +// HashMaps /////////////////////////////////////// // Operators /////////////////////////////////////// +System.out.println("\n->Operators"); int i1 = 1, i2 = 2; // Shorthand for multiple declarations // Arithmetic is straightforward -i1 + i2; // => 3 -i2 - i1; // => 1 -i2 * i1; // => 2 -i1 / i2; // => 0 (0.5, but truncated towards 0) +System.out.println("1+2 = "+(i1 + i2)); // => 3 +System.out.println("1+2 = "+(i2 - i1)); // => 1 +System.out.println("1+2 = "+(i2 * i1)); // => 2 +System.out.println("1+2 = "+(i1 / i2)); // => 0 (0.5, but truncated towards 0) // Modulo -11 % 3; // => 2 +System.out.println("11%3 = "+(11 % 3)); // => 2 // Comparison operators -3 == 2; // => 0 (false) -3 != 2; // => 1 (true) -3 > 2; // => 1 -3 < 2; // => 0 -2 <= 2; // => 1 -2 >= 2; // => 1 +System.out.println("3 == 2? "+(3 == 2)); // => 0 (false) +System.out.println("3 != 2? "+(3 != 2)); // => 1 (true) +System.out.println("3 > 2? "+(3 > 2)); // => 1 +System.out.println("3 < 2? "+(3 < 2)); // => 0 +System.out.println("2 <= 2? "+(2 <= 2)); // => 1 +System.out.println("2 >= 2? "+(2 >= 2)); // => 1 // Bitwise operators! +/* ~ Unary bitwise complement << Signed left shift >> Signed right shift @@ -140,100 +142,110 @@ i1 / i2; // => 0 (0.5, but truncated towards 0) & Bitwise AND ^ Bitwise exclusive OR | Bitwise inclusive OR +*/ // Incrementations int i=0; -i++; //i = 1. Post-Incrementation -++i; //i = 2. Pre-Incrementation -i--; //i = 1. Post-Decrementation ---i; //i = 0. Pre-Decrementation +System.out.println("\n->Inc/Dec-rementation"); +System.out.println(i++); //i = 1. Post-Incrementation +System.out.println(++i); //i = 2. Pre-Incrementation +System.out.println(i--); //i = 1. Post-Decrementation +System.out.println(--i); //i = 0. Pre-Decrementation /////////////////////////////////////// // Control Structures /////////////////////////////////////// - -if (false) { - System.out.println("I never run"); - } else if (false) { - System.out.println("I am also never run"); - } else { - System.out.println("I print"); - } +System.out.println("\n->Control Structures"); +if (false){ + System.out.println("I never run"); +}else if (false) { + System.out.println("I am also never run"); +} else { + System.out.println("I print"); } // While loop -int i = 0; -while(i < 100){ - System.out.println(i); +int fooWhile = 0; +while(fooWhile < 100) +{ + //System.out.println(fooWhile); //Increment the counter - i++; + //Iterated 99 times, fooWhile 0->99 + fooWhile++; } +System.out.println("fooWhile Value: "+fooWhile); // Do While Loop -int i = 0; -do{ - System.out.println(i); +int fooDoWhile = 0; +do +{ + //System.out.println(fooDoWhile); //Increment the counter - i++; -}while(i < 100); + //Iterated 99 times, fooDoWhile 0->99 + fooDoWhile++; +}while(fooDoWhile < 100); +System.out.println("fooDoWhile Value: "+fooDoWhile); // For Loop -int i; +int fooFor; //for loop structure => for(;;) -for(i=0;i<100;i++){ - System.out.println(i); +for(fooFor=0;fooFor<100;fooFor++){ + //System.out.println(fooFor); + //Iterated 99 times, fooFor 0->99 } +System.out.println("fooFor Value: "+fooFor); // Switch Case int month = 8; - String monthString; - switch (month) { - case 1: monthString = "January"; - break; - case 2: monthString = "February"; - break; - case 3: monthString = "March"; - break; - case 4: monthString = "April"; - break; - case 5: monthString = "May"; - break; - case 6: monthString = "June"; - break; - case 7: monthString = "July"; - break; - case 8: monthString = "August"; - break; - case 9: monthString = "September"; - break; - case 10: monthString = "October"; - break; - case 11: monthString = "November"; - break; - case 12: monthString = "December"; - break; - default: monthString = "Invalid month"; - break; - } - System.out.println(monthString); +String monthString; +switch (month){ + case 1: monthString = "January"; + break; + case 2: monthString = "February"; + break; + case 3: monthString = "March"; + break; + case 4: monthString = "April"; + break; + case 5: monthString = "May"; + break; + case 6: monthString = "June"; + break; + case 7: monthString = "July"; + break; + case 8: monthString = "August"; + break; + case 9: monthString = "September"; + break; + case 10: monthString = "October"; + break; + case 11: monthString = "November"; + break; + case 12: monthString = "December"; + break; + default: monthString = "Invalid month"; + break; +} +System.out.println("Switch Case Result: "+monthString); /////////////////////////////////////// -// Typecasting +// Converting Data Types And Typcasting /////////////////////////////////////// // Converting data -//Convert String To Integer +// Convert String To Integer Integer.parseInt("123");//returns an integer version of "123" -//Convert Integer To String +// Convert Integer To String Integer.toString(123);//returns a string version of 123 -//For other conversions check out the following classes: -//Double -//Long -//String +// For other conversions check out the following classes: +// Double +// Long +// String +// Typecsating // You can also cast java objects, there's a lot of details and // deals with some more intermediate concepts. // Feel free to check it out here: http://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html @@ -243,66 +255,77 @@ Integer.toString(123);//returns a string version of 123 // Classes And Functions /////////////////////////////////////// -// Classes Syntax shown below. -// Function declaration syntax: -// () -// Here is a quick rundown on access level modifiers (public, private, etc.) -// http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html - - -public class Bicycle { - - // Bicycle's Fields/Variables - public int cadence; - public int gear; - public int speed; - - // Constructors are a way of creating classes - // This is a default constructor - public Bicycle(){ - gear = 1; - cadence = 50; - startGear = 1; - } - - // This is a specified constructor (it contains arguments) - public Bicycle(int startCadence, int startSpeed, int startGear) { - gear = startGear; - cadence = startCadence; - speed = startSpeed; - } - - // the Bicycle class has - // four methods - public void setCadence(int newValue) { - cadence = newValue; - } + // Read about the class, and function syntax before + // reading this. + System.out.println("\n->Classes & Functions"); + // Call bicycle's constructor + Bicycle trek = new Bicycle(); + // Manipulate your object + trek.speedUp(3); + trek.setCadence(100); + System.out.println("trek info: "+trek.toString()); + + // Classes Syntax: + // class { + // //data fields, constructors, functions all inside + // } + // Function Syntax: + // () + // Here is a quick rundown on access level modifiers (public, private, etc.) + // http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html + +// This bracket ends the main method +} + // The static field is only required because this class + // is nested inside of the learnjava.java class. + public static class Bicycle { + + // Bicycle's Fields/Variables + public int cadence; + public int gear; + public int speed; + + // Constructors are a way of creating classes + // This is a default constructor + public Bicycle(){ + gear = 1; + cadence = 50; + speed = 5; + } - public void setGear(int newValue) { - gear = newValue; - } + // This is a specified constructor (it contains arguments) + public Bicycle(int startCadence, int startSpeed, int startGear) { + gear = startGear; + cadence = startCadence; + speed = startSpeed; + } - public void applyBrake(int decrement) { - speed -= decrement; - } + // the Bicycle class has + // four functions/methods + public void setCadence(int newValue) { + cadence = newValue; + } - public void speedUp(int increment) { - speed += increment; - } + public void setGear(int newValue) { + gear = newValue; + } -} + public void applyBrake(int decrement) { + speed -= decrement; + } -//Now..Later in the main / driver of your java program -public class Main -{ - public static void main (String[] args) throws java.lang.Exception - { - //Call bicycle's constructor - Bicycle trek = new Bicycle(); - //Manipulate your object - trek.speedUp(3); - trek.setCadence(100); + public void speedUp(int increment) { + speed += increment; + } + + public String toString(){ + return "gear: "+Integer.toString(gear)+ + " cadence: "+Integer.toString(cadence)+ + " speed: "+Integer.toString(speed); + } + // bracket to close nested Bicycle class } +// bracket to close learnjava.java } ``` -- cgit v1.2.3