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[java/en] few changes (#2788)

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Mathieu Gemard 2017-07-09 18:39:21 +02:00 committed by ven
parent b67ac8da07
commit 4a359c303f
1 changed files with 55 additions and 66 deletions
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53
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@ -120,7 +120,8 @@ public class LearnJava {
// Initialize a variable using <type> <name> = <val>
int barInt = 1;
// Initialize multiple variables of same type with same
// value <type> <name1>, <name2>, <name3> = <val>
// value <type> <name1>, <name2>, <name3>
// <name1> = <name2> = <name3> = <val>
int barInt1, barInt2, barInt3;
barInt1 = barInt2 = barInt3 = 1;
@ -416,6 +417,7 @@ public class LearnJava {
// 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.
// Starting in Java 7 and above, we can also use the String type.
int month = 3;
String monthString;
switch (month) {
@ -430,23 +432,6 @@ public class LearnJava {
}
System.out.println("Switch Case Result: " + monthString);
// Starting in Java 7 and above, switching Strings works like this:
String myAnswer = "maybe";
switch(myAnswer) {
case "yes":
System.out.println("You answered yes.");
break;
case "no":
System.out.println("You answered no.");
break;
case "maybe":
System.out.println("You answered maybe.");
break;
default:
System.out.println("You answered " + myAnswer);
break;
}
// Try-with-resources (Java 7+)
// Try-catch-finally statements work as expected in Java but in Java 7+
@ -481,7 +466,7 @@ public class LearnJava {
System.out.println(bar); // Prints A, because the statement is true
////////////////////////////////////////
// Converting Data Types And Typecasting
// Converting Data Types
////////////////////////////////////////
// Converting data
@ -497,11 +482,6 @@ public class LearnJava {
// Long
// 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:
// https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html
///////////////////////////////////////
// Classes And Functions
///////////////////////////////////////
@ -652,6 +632,14 @@ class PennyFarthing extends Bicycle {
}
}
// Object casting
// Since the PennyFarthing class is extending the Bicycle class, we can say
// a PennyFarthing is a Bicycle and write :
// Bicycle bicycle = new PennyFarthing();
// This is called object casting where an object is taken for another one. There
// are lots of details and deals with some more intermediate concepts here:
// https://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html
// Interfaces
// Interface declaration syntax
// <access-level> interface <interface-name> extends <super-interfaces> {
@ -667,10 +655,10 @@ public interface Edible {
public interface Digestible {
public void digest();
// In Java 8, interfaces can have default method.
// public void digest() {
// System.out.println("digesting ...");
// }
// Since Java 8, interfaces can have default method.
public void defaultMethod() {
System.out.println("Hi from default method ...");
}
}
// We can now create a class that implements both of these interfaces.
@ -703,14 +691,15 @@ public class ExampleClass extends ExampleClassParent implements InterfaceOne,
// Abstract Classes
// Abstract Class declaration syntax
// <access-level> abstract <abstract-class-name> extends <super-abstract-classes> {
// <access-level> abstract class <abstract-class-name> extends
// <super-abstract-classes> {
// // Constants and variables
// // Method declarations
// }
// Marking a class as abstract means that it contains abstract methods that
// must be defined in a child class. Similar to interfaces, abstract classes
// cannot be instantiated, but instead must be extended and the abstract
// 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,