Creating Uruk Hais

Revision as of 02:00, 1 October 2012 (view source)

(Created page with "Saruman did not create single monsters to attack the lands of men. Each '''class''' is a race composed of many individuals ('''instances''' or '''objects'''.) The most horrible...")

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# Which instance variable of each object is set directly?

# If you inserted 'one.sharedBattleCry = "Meep!";' before the declamations, what would change in the declamations? Why?

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== Static And Regular Methods ==

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The '''static''' reserved word distinguishes class variables from instance variables. It also has an important meaning for methods. A static (class) method may not use any instance variables, though it can use class variables. A static method may be called by its class or by one of the instances of the class with the dot notation. But a non-static, regular method cannot be called by its class because the class has no instance variables and the method might use them.

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# Paste the line 'UrukHai.screamTheSharedBattleCry();' at the end of main(). Look at UrukHai, and predict if it will work. Explain why.

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# Paste the line 'one.screamTheSharedBattleCry();' at the end of main(). Look at UrukHai, and predict if it will work. Explain why.

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# Paste the line 'UrukHai.declaim();' at the end of main(). Look at UrukHai, and predict if it will work. Explain why.

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== It Is Forbidden! ==

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At last the secret meanings of the keywords '''public''' and '''private''' may be revealed to you.

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* Public means that a variable or method of a class may be used by any other class.

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* Private means that a variable or method of a class may be used only within the same class.

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This is the secret of '''encapsulation''', the principle of hiding the inner workings of a class. The public parts of a class are called the '''interface''', the private parts are concealed.

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@@ Line 48: / Line 48: @@
 # Which instance variable of each object is set directly?
 # If you inserted 'one.sharedBattleCry = "Meep!";' before the declamations, what would change in the declamations?  Why?
+== Static And Regular Methods ==
+The '''static''' reserved word distinguishes class variables from instance variables.  It also has an important meaning for methods.  A static (class) method may not use any instance variables, though it can use class variables.  A static method may be called by its class or by one of the instances of the class with the dot notation.  But a non-static, regular method cannot be called by its class because the class has no instance variables and the method might use them.
+# Paste the line 'UrukHai.screamTheSharedBattleCry();' at the end of main().  Look at UrukHai, and predict if it will work.  Explain why.
+# Paste the line 'one.screamTheSharedBattleCry();' at the end of main().  Look at UrukHai, and predict if it will work.  Explain why.
+# Paste the line 'UrukHai.declaim();' at the end of main().  Look at UrukHai, and predict if it will work.  Explain why.
+== It Is Forbidden! ==
+At last the secret meanings of the keywords '''public''' and '''private''' may be revealed to you.
+* Public means that a variable or method of a class may be used by any other class.
+* Private means that a variable or method of a class may be used only within the same class.
+This is the secret of '''encapsulation''', the principle of hiding the inner workings of a class.  The public parts of a class are called the '''interface''', the private parts are concealed.