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Java generics type erasure: when and what happens?

...cs are used, they're converted into compile-time checks and execution-time casts. So this code: List<String> list = new ArrayList<String>(); list.add("Hi"); String x = list.get(0); is compiled into List list = new ArrayList(); list.add("Hi"); String x = (String) list.get(0); At exe...
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What causes javac to issue the “uses unchecked or unsafe operations” warning

... as the use of raw types (as described by the other answers), an unchecked cast can also cause the warning. Once you've compiled with -Xlint, you should be able to rework your code to avoid the warning. This is not always possible, particularly if you are integrating with legacy code that cannot b...
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What is a covariant return type?

...ference to a MyFoo object will be able to invoke clone() and know (without casting) that the return value is an instance of MyFoo. Without covariant return types, the overridden method in MyFoo would have to be declared to return Object - and so calling code would have to explicitly downcast the re...
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Why use symbols as hash keys in Ruby?

... basically "immutable strings" .. that means that they can not be changed, and it implies that the same symbol when referenced many times throughout your source code, is always stored as the same entity, e.g. has the same object id. Strings on the other hand are mutable, they can be changed anytim...
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Formatting Numbers by padding with leading zeros in SQL Server

...pad with 4 leading zero :) declare @number int = 1; print right('0000' + cast(@number as varchar(4)) , 4) print right('0000' + convert(varchar(4), @number) , 4) print right(replicate('0',4) + convert(varchar(4), @number) , 4) print cast(replace(str(@number,4),' ','0')as char(4)) print format(@num...
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C# : 'is' keyword and checking for Not

...... Update (considering the OP's code snippet): Since you're actually casting the value afterward, you could just use as instead: public void Update(DocumentPart part) { part.Update(); IContainer containerPart = part as IContainer; if(containerPart == null) return; foreach(Docu...
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Int division: Why is the result of 1/3 == 0?

... Explicitly cast it as a double double g = 1.0/3.0 This happens because Java uses the integer division operation for 1 and 3 since you entered them as integer constants. ...
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How do I select a random value from an enumeration?

...lues from Type provided .OfType<Enum>() // casts to Enum .OrderBy(e => Guid.NewGuid()) // mess with order of results .FirstOrDefault(); // take first item in result } } public static class Program { public enum SomeEnum ...
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UICollectionView spacing margins

... This works, but the collection.collectionViewLayout needs a cast as in the example by @Pooja: UICollectionViewFlowLayout *flow = (UICollectionViewFlowLayout*) self.collectionViewLayout; – jwj Dec 5 '13 at 18:56 ...
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Sending Arguments To Background Worker?

...s List<object>; extract your multiple arguments from this list and cast them and use them. } share | improve this answer | follow | ...