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| -rw-r--r-- | java.html.markdown | 171 |
1 files changed, 80 insertions, 91 deletions
diff --git a/java.html.markdown b/java.html.markdown index 10dd498c..363a16f6 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -1,16 +1,16 @@ --- - language: java contributors: - ["Jake Prather", "http://github.com/JakeHP"] - - ["Madison Dickson", "http://github.com/mix3d"] - ["Jakukyo Friel", "http://weakish.github.io"] + - ["Madison Dickson", "http://github.com/mix3d"] + - ["Simon Morgan", "http://sjm.io/"] filename: LearnJava.java - --- -Java is a general-purpose, concurrent, class-based, object-oriented computer programming language. -[Read more here.](http://docs.oracle.com/javase/tutorial/java/index.html) +Java is a general-purpose, concurrent, class-based, object-oriented computer +programming language. +[Read more here.](http://docs.oracle.com/javase/tutorial/java/) ```java // Single-line comments start with // @@ -101,10 +101,10 @@ public class LearnJava { System.out.println(bazString); // Arrays - //The array size must be decided upon instantiation - //The following formats work for declaring an array - //<datatype>[] <var name> = new <datatype>[<array size>]; - //<datatype> <var name>[] = new <datatype>[<array size>]; + // The array size must be decided upon instantiation + // The following formats work for declaring an array + // <datatype>[] <var name> = new <datatype>[<array size>]; + // <datatype> <var name>[] = new <datatype>[<array size>]; int[] intArray = new int[10]; String[] stringArray = new String[1]; boolean boolArray[] = new boolean[100]; @@ -122,17 +122,17 @@ public class LearnJava { System.out.println("intArray @ 1: " + intArray[1]); // => 1 // Others to check out - // ArrayLists - Like arrays except more functionality is offered, - // and the size is mutable + // ArrayLists - Like arrays except more functionality is offered, and + // the size is mutable // LinkedLists - Implementation of doubly-linked list. All of the - // operations perform as could be expected for - // a doubly-linked list. - // Maps - A set of objects that maps keys to values. A map cannot contain - // duplicate keys; each key can map to at most one value. - // HashMaps - This class uses a hashtable to implement the Map interface. - // This allows the execution time of basic operations, - // such as get and insert element, to remain constant even - // for large sets. + // operations perform as could be expected for a + // doubly-linked list. + // Maps - A set of objects that maps keys to values. A map cannot + // contain duplicate keys; each key can map to at most one value. + // HashMaps - This class uses a hashtable to implement the Map + // interface. This allows the execution time of basic + // operations, such as get and insert element, to remain + // constant even for large sets. /////////////////////////////////////// // Operators @@ -175,10 +175,10 @@ public class LearnJava { // The ++ and -- operators increment and decrement by 1 respectively. // If they are placed before the variable, they increment then return; // after the variable they return then increment. - System.out.println(i++); //i = 1, prints 0 (post-increment) - System.out.println(++i); //i = 2, prints 2 (pre-increment) - System.out.println(i--); //i = 1, prints 2 (post-decrement) - System.out.println(--i); //i = 0, prints 0 (pre-decrement) + System.out.println(i++); // i = 1, prints 0 (post-increment) + System.out.println(++i); // i = 2, prints 2 (pre-increment) + System.out.println(i--); // i = 1, prints 2 (post-decrement) + System.out.println(--i); // i = 0, prints 0 (pre-decrement) /////////////////////////////////////// // Control Structures @@ -197,73 +197,68 @@ public class LearnJava { // While loop int fooWhile = 0; - while(fooWhile < 100) - { - //System.out.println(fooWhile); - //Increment the counter - //Iterated 100 times, fooWhile 0,1,2...99 + while(fooWhile < 100) { + System.out.println(fooWhile); + // Increment the counter + // Iterated 100 times, fooWhile 0,1,2...99 fooWhile++; } System.out.println("fooWhile Value: " + fooWhile); // Do While Loop int fooDoWhile = 0; - do - { - //System.out.println(fooDoWhile); - //Increment the counter - //Iterated 99 times, fooDoWhile 0->99 + do { + System.out.println(fooDoWhile); + // Increment the counter + // Iterated 99 times, fooDoWhile 0->99 fooDoWhile++; - }while(fooDoWhile < 100); + } while(fooDoWhile < 100); System.out.println("fooDoWhile Value: " + fooDoWhile); // For Loop int fooFor; - //for loop structure => for(<start_statement>; <conditional>; <step>) - for(fooFor=0; fooFor<10; fooFor++){ - //System.out.println(fooFor); - //Iterated 10 times, fooFor 0->9 + // for loop structure => for(<start_statement>; <conditional>; <step>) + for(fooFor = 0; fooFor < 10; fooFor++){ + System.out.println(fooFor); + // Iterated 10 times, fooFor 0->9 } System.out.println("fooFor Value: " + fooFor); // For Each Loop // An automatic iteration through an array or list of objects. int[] fooList = {1,2,3,4,5,6,7,8,9}; - //for each loop structure => for(<object> : <array_object>) - //reads as: for each object in the array - //note: the object type must match the array. + // for each loop structure => for(<object> : <array_object>) + // reads as: for each object in the array + // note: the object type must match the array. - for( int bar : fooList ){ - //System.out.println(bar); + for (int bar : fooList){ + System.out.println(bar); //Iterates 9 times and prints 1-9 on new lines } // Switch Case // A switch works with the byte, short, char, and int data types. - // It also works with enumerated types (discussed in Enum Types), - // the String class, and a few special classes that wrap - // primitive types: Character, Byte, Short, and Integer. + // It also works with enumerated types (discussed in Enum Types), the + // String class, and a few special classes that wrap primitive types: + // Character, Byte, Short, and Integer. int month = 3; String monthString; - switch (month){ - case 1: - monthString = "January"; - break; - case 2: - monthString = "February"; + switch (month) { + case 1: monthString = "January"; break; - case 3: - monthString = "March"; + case 2: monthString = "February"; break; - default: - monthString = "Some other month"; + case 3: monthString = "March"; break; + default: monthString = "Some other month"; + break; } System.out.println("Switch Case Result: " + monthString); // Conditional Shorthand // You can use the '?' operator for quick assignments or logic forks. - // Reads as "If (statement) is true, use <first value>, otherwise, use <second value>" + // Reads as "If (statement) is true, use <first value>, otherwise, use + // <second value>" int foo = 5; String bar = (foo < 10) ? "A" : "B"; System.out.println(bar); // Prints A, because the statement is true @@ -287,9 +282,8 @@ public class LearnJava { // String // Typecasting - // 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: + // 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 @@ -319,9 +313,9 @@ public class LearnJava { // Class Declaration Syntax: -// <public/private/protected> class <class name>{ -// //data fields, constructors, functions all inside. -// //functions are called as methods in Java. +// <public/private/protected> class <class name> { +// // data fields, constructors, functions all inside. +// // functions are called as methods in Java. // } class Bicycle { @@ -342,7 +336,8 @@ class Bicycle { } // This is a constructor that takes arguments - public Bicycle(int startCadence, int startSpeed, int startGear, String name) { + public Bicycle(int startCadence, int startSpeed, int startGear, + String name) { this.gear = startGear; this.cadence = startCadence; this.speed = startSpeed; @@ -388,10 +383,8 @@ class Bicycle { //Method to display the attribute values of this Object. @Override public String toString() { - return "gear: " + gear + - " cadence: " + cadence + - " speed: " + speed + - " name: " + name; + return "gear: " + gear + " cadence: " + cadence + " speed: " + speed + + " name: " + name; } } // end class Bicycle @@ -405,26 +398,26 @@ class PennyFarthing extends Bicycle { super(startCadence, startSpeed, 0, "PennyFarthing"); } - // You should mark a method you're overriding with an @annotation - // To learn more about what annotations are and their purpose - // check this out: http://docs.oracle.com/javase/tutorial/java/annotations/ + // You should mark a method you're overriding with an @annotation. + // To learn more about what annotations are and their purpose check this + // out: http://docs.oracle.com/javase/tutorial/java/annotations/ @Override public void setGear(int gear) { gear = 0; } - } -//Interfaces -//Interface declaration syntax -//<access-level> interface <interface-name> extends <super-interfaces> { -// //Constants -// //Method declarations -//} +// Interfaces +// Interface declaration syntax +// <access-level> interface <interface-name> extends <super-interfaces> { +// // Constants +// // Method declarations +// } -//Example - Food: +// Example - Food: public interface Edible { - public void eat(); //Any class that implements this interface, must implement this method + public void eat(); // Any class that implements this interface, must + // implement this method. } public interface Digestible { @@ -432,33 +425,31 @@ public interface Digestible { } -//We can now create a class that implements both of these interfaces +// We can now create a class that implements both of these interfaces. public class Fruit implements Edible, Digestible { @Override public void eat() { - //... + // ... } @Override public void digest() { - //... + // ... } } -//In java, you can extend only one class, but you can implement many interfaces. -//For example: -public class ExampleClass extends ExampleClassParent implements InterfaceOne, InterfaceTwo { +// In Java, you can extend only one class, but you can implement many +// interfaces. For example: +public class ExampleClass extends ExampleClassParent implements InterfaceOne, + InterfaceTwo { @Override public void InterfaceOneMethod() { - } @Override public void InterfaceTwoMethod() { - } } - ``` ## Further Reading @@ -500,5 +491,3 @@ The links provided here below are just to get an understanding of the topic, fee * [Objects First with Java](http://www.amazon.com/Objects-First-Java-Practical-Introduction/dp/0132492660) * [Java The Complete Reference](http://www.amazon.com/gp/product/0071606300) - - |