diff options
| author | Adam <adam@adambard.com> | 2013-06-30 14:54:21 -0700 | 
|---|---|---|
| committer | Adam <adam@adambard.com> | 2013-06-30 14:54:21 -0700 | 
| commit | 329eba20a5d64f72091a6b9faf2eff7e246d3d9d (patch) | |
| tree | 7276a03b771b1cfe76516645dbf708becfa37e98 /java.html.markdown | |
| parent | f7cd75c31bbca713cc66b3b46568472a2a1665fd (diff) | |
| parent | fbe0fb471896e55c40d734b082f5e994e6dc775d (diff) | |
Merge branch 'patch-2' of github.com:Jakehp/learnxinyminutes-docs into jakehp-patch-2
Diffstat (limited to 'java.html.markdown')
| -rw-r--r-- | java.html.markdown | 377 | 
1 files 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:  //<datatype> [] <var name> = new <datatype>[<array size>]; -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(<start_statement>;<conditional>;<step>) -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: -// <public/private/protected> <return type> <function name>(<args>) -// 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: +	// <public/private/protected> class <class name>{ +	//    //data fields, constructors, functions all inside +	// } +	// Function Syntax: +	// <public/private/protected> <return type> <function name>(<args>) +	// 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  }  ``` | 
