From 7559305fb74cc9750a1d45ea24803257d27a8c88 Mon Sep 17 00:00:00 2001 From: Sridhar Easwaran Date: Thu, 5 Oct 2017 14:40:34 +0530 Subject: added use of break keyword & new tutorial link --- java.html.markdown | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'java.html.markdown') diff --git a/java.html.markdown b/java.html.markdown index fa1ff3d1..d1ce2233 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -418,6 +418,8 @@ public class LearnJava { // String class, and a few special classes that wrap primitive types: // Character, Byte, Short, and Integer. // Starting in Java 7 and above, we can also use the String type. + // Note: Do remember that, not adding "break" at end any particular case ends up in + // executing the very next case(given it satisfies the condition provided) as well. int month = 3; String monthString; switch (month) { @@ -886,6 +888,8 @@ The links provided here below are just to get an understanding of the topic, fee * [Codingbat.com](http://codingbat.com/java) +* [Codewars - Java Katas](https://www.codewars.com/?language=java) + **Books**: * [Head First Java](http://www.headfirstlabs.com/books/hfjava/) -- cgit v1.2.3 From 8bccfb8be287e8f85129a45abb046a3f27b1e0dd Mon Sep 17 00:00:00 2001 From: Toby Sullivan Date: Thu, 5 Oct 2017 12:19:40 -0700 Subject: Add default keyword --- java.html.markdown | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'java.html.markdown') diff --git a/java.html.markdown b/java.html.markdown index fa1ff3d1..a8c2523c 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -660,7 +660,7 @@ public interface Edible { public interface Digestible { public void digest(); // Since Java 8, interfaces can have default method. - public void defaultMethod() { + public default void defaultMethod() { System.out.println("Hi from default method ..."); } } -- cgit v1.2.3 From 56a82546e9196a94a0085eae0abd0578702a578f Mon Sep 17 00:00:00 2001 From: Andrew Gallasch Date: Sat, 28 Oct 2017 15:36:34 +1030 Subject: Improve comment about final modifier --- java.html.markdown | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'java.html.markdown') diff --git a/java.html.markdown b/java.html.markdown index 7b59b085..73e4bd2e 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -173,7 +173,7 @@ public class LearnJava { // Char - A single 16-bit Unicode character char fooChar = 'A'; - // final variables can't be reassigned to another object, + // final variables can't be reassigned, final int HOURS_I_WORK_PER_WEEK = 9001; // but they can be initialized later. final double E; -- cgit v1.2.3 From 32090679c2a6a79933fa94f36a7dcddd22a20897 Mon Sep 17 00:00:00 2001 From: Andrew Gallasch Date: Sat, 28 Oct 2017 16:09:07 +1030 Subject: Improve comments on abstract classes --- java.html.markdown | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) (limited to 'java.html.markdown') diff --git a/java.html.markdown b/java.html.markdown index 73e4bd2e..621d500c 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -703,15 +703,21 @@ public class ExampleClass extends ExampleClassParent implements InterfaceOne, // // Method declarations // } -// Marking a class as abstract means that it contains at least one abstract -// method that must be defined in a child class. Similar to interfaces, abstract -// classes cannot be instantiated, but instead must be extended and the abstract -// methods defined. Different from interfaces, abstract classes can contain a -// mixture of concrete and abstract methods. Methods in an interface cannot -// have a body, unless the method is static, and variables are final by default, -// unlike an abstract class. Also abstract classes CAN have the "main" method. +// Abstract Classes cannot be instantiated. +// Abstract classes may define abstract methods. +// Abstract methods have no body and are marked abstract +// Non-abstract child classes must @Override all abstract methods +// from their super-classes. +// Abstract classes can be useful when combining repetitive logic +// with customised behavior, but as Abstract classes require +// inheritance, they violate "Composition over inheritance" +// so consider other approaches using composition. +// https://en.wikipedia.org/wiki/Composition_over_inheritance + public abstract class Animal { + private int age; + public abstract void makeSound(); // Method can have a body @@ -722,17 +728,12 @@ public abstract class Animal age = 30; } - // No need to initialize, however in an interface - // a variable is implicitly final and hence has - // to be initialized. - private int age; - public void printAge() { System.out.println(age); } - // Abstract classes can have main function. + // Abstract classes can have main method. public static void main(String[] args) { System.out.println("I am abstract"); -- cgit v1.2.3 From d1ed7e02da50f3e03e517175b1ff866332c049f2 Mon Sep 17 00:00:00 2001 From: Andrew Gallasch Date: Mon, 30 Oct 2017 23:55:40 +1030 Subject: Improve TreeMap documentation --- java.html.markdown | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) (limited to 'java.html.markdown') diff --git a/java.html.markdown b/java.html.markdown index 621d500c..36d56625 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -280,7 +280,7 @@ public class LearnJava { // 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 map keys to values. Map is + // Maps - A mapping of key Objects to value Objects. Map is // an interface and therefore cannot be instantiated. // The type of keys and values contained in a Map must // be specified upon instantiation of the implementing @@ -289,10 +289,16 @@ public class LearnJava { // 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. - // TreeMap - This class is a sorted tree structure. It implements a red - // black tree and sorts the entries based on the key value or - // the comparator provided while creating the object + // constant-amortized even for large sets. + // TreeMap - A Map that is sorted by its keys. Each modification + // maintains the sorting defined by either a Comparator + // supplied at instantiation, or comparisons of each Object + // if they implement the Comparable interface. + // Failure of keys to implement Comparable combined with failure to + // supply a Comparator will throw ClassCastExceptions. + // Insertion and removal operations take O(log(n)) time + // so avoid using this data structure unless you are taking + // advantage of the sorting. /////////////////////////////////////// // Operators -- cgit v1.2.3 From 833c7bea6ced906d32e4029e704d1a2a831c9b05 Mon Sep 17 00:00:00 2001 From: Andrew Gallasch Date: Mon, 30 Oct 2017 23:58:22 +1030 Subject: Improve arithmetic output --- java.html.markdown | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'java.html.markdown') diff --git a/java.html.markdown b/java.html.markdown index 36d56625..dd875c16 100644 --- a/java.html.markdown +++ b/java.html.markdown @@ -312,7 +312,7 @@ public class LearnJava { System.out.println("2-1 = " + (i2 - i1)); // => 1 System.out.println("2*1 = " + (i2 * i1)); // => 2 System.out.println("1/2 = " + (i1 / i2)); // => 0 (int/int returns int) - System.out.println("1/2 = " + (i1 / (double)i2)); // => 0.5 + System.out.println("1/2.0 = " + (i1 / (double)i2)); // => 0.5 // Modulo System.out.println("11%3 = "+(11 % 3)); // => 2 -- cgit v1.2.3