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Topic: ArrayList (Read 2044 times) |
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benelek
 
 
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ArrayList
« on: Apr 12th, 2003, 9:20am » |
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g'day all,
im having some trouble understanding the relationship between the Object class and its children classes. for example, why doesn't the following work, if an int is a subclass of Object? and if you can't assign a value of type 'int' to a variable of type 'Object', what can you assign to a variable of type 'Object'?
Code:
and...
Code:Object moo;
int mooner=15;
moo=mooner; |
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-jacob
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benelek
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Re: ArrayList
« Reply #1 on: Apr 12th, 2003, 9:44am » |
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uh... looks like i got ahead of myself with the topic of the post  anyway, here's the part about the ArrayList class:
Code:
int mooner = 15;
Integer mooner2 = new Integer(mooner);
Object moo = new Integer(mooner);
ArrayList mooList = new ArrayList();
mooList.add(moo);
//mooList.add(mooner); //try this.
mooList.add(mooner2);
println(random(5));
println(mooList.get(0).getClass());
println(mooList.get(1).getClass());
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using the "Integer" class works as an Object, but using an "int" doesnt. isnt the "int" class a subclass of Object?
-jacob
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fry
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Re: ArrayList
« Reply #2 on: Apr 13th, 2003, 1:23am » |
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nope, the rule of thumb is that only the all-caps names are subclasses of Object. int, float, byte, char, etc are basic elements that aren't classes. this is done primarily for speed reasons in the java virtual machine.
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benelek
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Re: ArrayList
« Reply #3 on: Apr 13th, 2003, 3:44am » |
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rightyo *major stumbling block falls*
thanks
-jacob
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