The Knowledge Of Sauron's Minions
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Welcome to Rivendell! You have completed your stay at Hogwarts and have come here to study Java even further, to learn the dark secrets of Sauron. | Welcome to Rivendell! You have completed your stay at Hogwarts and have come here to study Java even further, to learn the dark secrets of Sauron. | ||
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| + | ==Revealing The Knowledge== | ||
Sauron knows whatever his servants, the RingWraiths, know, thus it is essential to learn of the types of knowledge RingWraiths and other fell classes can possess. | Sauron knows whatever his servants, the RingWraiths, know, thus it is essential to learn of the types of knowledge RingWraiths and other fell classes can possess. | ||
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public class RingWraith | public class RingWraith | ||
{ | { | ||
| + | // variables | ||
static public int iAmOneOf = 7; | static public int iAmOneOf = 7; | ||
static public double myAgeIs= 2734.81; | static public double myAgeIs= 2734.81; | ||
| − | static public char exclaim = | + | static public char exclaim = '!'; |
static public boolean iBearARing = true; | static public boolean iBearARing = true; | ||
static public String iServeTheDarkLord = "Sauron"; | static public String iServeTheDarkLord = "Sauron"; | ||
| + | // methods | ||
static public void main(String[] args) | static public void main(String[] args) | ||
{ | { | ||
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} | } | ||
</pre> | </pre> | ||
| + | There is only one method, main(), in this RingWraith class: the other statements at the beginning declare '''variables'''. The five variables here are the most frequently used sorts. | ||
| + | |||
| + | There are many '''basic types''', but here we shall concern ourselves with only four. | ||
| + | |||
| + | If you wish to represent an integer, then your variable should be of the basic type '''int'''. Yet even evil has its limits: an int variable can only represent numbers up to about 2 billion and down to negative 2 billion. We will delve into that mystery later. | ||
| + | |||
| + | If you wish to represent a real number, to have decimal points, to calculate fractions, to cleverly calculate the moon and sun, then you must use the basic type '''double'''. | ||
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| + | The basic type '''boolean''' is the simplest of all yet represents the atom of all calculation, all knowledge: it can represent only true or false. All else can be built of boolean, but the labor is extremely difficult. | ||
| + | |||
| + | Betimes a single character must be represented, thus the basic type '''char'''. | ||
| + | |||
| + | Type '''String''' is not a basic type: it is a '''class''' and variables of type String are called '''objects'''. String is one of the important classes that come with Java, and one of the most frequently used classes. | ||
| + | |||
| + | ==Further Revellations== | ||
| + | |||
| + | * Trap the RingWraith code within Dr. Java. | ||
| + | * Note the different colors of the code. What could they signify? | ||
| + | * Pull down the Dr. Java menu and select Preferences. In the Categories section, select Display Options and then Colors. | ||
| + | * Make a note of how you find each color (from Normal Color to Brace-matching Color) in the code. | ||
| + | * Brace-matching Color is tricky. How do you reveal it in the code? | ||
| + | * I can hardly see the Type Color in the code. Click the ellipsis (...) button to the right of Type Color, and change the color to a dark red. Click Apply and OK. More visible now? | ||
| + | * '''Keyword''' means the same as '''reserved word'''. We have one of these magic words posted on high: which others should we add now? | ||
| + | * The basic types are also reserved words: what else then should we add to our list of reserved words? | ||
| + | * Why shouldn't we add String to the reserved words? | ||
| + | * Look at the variable names. What pattern of capitalization do you observe? | ||
| + | * Each of the variables is SET with a value. These written values are called '''literal constants'''. | ||
| + | * The exception is boolean: '''true''' and '''false''' are reserved words. | ||
| + | |||
| + | ==The Arcane Knowledge== | ||
| + | * Add another variable to RingWraith, of type double and named "compute". | ||
| + | * Inside main(), add 'compute = Math.sin(Math.PI/6);' | ||
| + | * Print out the value of compute with the proper incantation. | ||
| + | * Look on my page for "References", and click on Math. Explore therein and find the secrets of exponentiation and other precalculus functions. | ||
