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Java Collection Q&A
3.Array Byte
4.Array Char
5.Array Convert
6.Array Dimension
7.Array Integer
8.Array Object
9.Array String
14.Garbage Collection
Java Collection Q&A » collection » toArray 

1. What to pass to the Arrays instance method toArray(T[] a) method?

If you have an instance of a Collection, say something like:

Collection<String> addresses = new ArrayList<String>();
Which were to then be populated with a bunch of values, which is the "best" way, if ...

2. Java: how to implement `toArray` for `Collection`

Right now, I have:

    public <T> T[] toArray(T[] old) {
        T[] arr = Arrays.copyOf(old, old.length + size());

3. Why does Java's Collection.toArray() return an Object[] rather than an E[]?

Before Java generics, Collection.toArray() had no way to know which type of array the developer expected (particularly for an empty collection). As I understand it, this was the main rationale behind ...

4. What would be the correct syntax for Collection.toArray()

Collection.toArray We use the above method to convert a List<String> object to an equivalent String[].

List<String> foos = new ArrayList<String>();
// foos.toArray(new String[0]);
// foos.toArray(new String[foos.length]);
Which would be the right method to use ...

5. Call to Collection.toArray() can be optimized? How?

I'm using PMD to analyze my code and one of the comments I get is: Call to Collection.toArray() may be optimizable In what way can it be optimizable? For example, I have lines of code that look like: Array errorList = new ArrayList(); ... do stuff and errorList.add(object); ... and then at the end I do (OperationException[])errorList.toArray(new OperationException[0])) (basically convert the ...

6. Collection.toArray Problem

Here is my declaration: SelectedAsset selectedAsset[]= null; Collection selectedAssetsCollection; in the method I am calling follwing code. selectedAsset = new SelectedAsset[selectedAssetsCollection.size()]; selectedAsset=(SelectedAsset[])selectedAssetsCollection.toArray(); when I checked selectedAssetsCollection.size() returns me size 1. But it gives me classcast exception, while it contains object of type SelectedAsset. I wonder for this awkword behave with toArray method.

7. toArray method in Collection

"new String[0]" creates a new array of type string that can hold 0 elements. There is already a discussion around here somewhere about why that can be useful, but Collection.toArray is where it is used quite often just to get the return type correctly. Please note that "new String[list.size()]" will be a bit more efficient; with 0 you'll create two arrays ...

8. Collections - toArray Method

The Collection Documentation States: "The toArray methods are provided as a bridge between collections and older APIs that expect arrays on input. They allow the contents of a Collection to be translated into an array. The simple form with no arguments creates a new array of Object. The more complex form allows the caller to provide an array or to choose ...

9. How collection.toArray() works?

10. Collection toArray() help.  | Contact Us | Privacy Policy
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