Convert lists to arrays in Java | Java Debug Notes

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Convert lists to arrays in Java

How can I convert List to ArrayJava?

Check the following code:

ArrayList<Tienda> tiendas;
List<Tienda> tiendasList; 
tiendas = new ArrayList<Tienda>();

Resources res = this.getBaseContext().getResources();
XMLParser saxparser =  new XMLParser(marca,res);

tiendasList = saxparser.parse(marca,res);
tiendas = tiendasList.toArray();

this.adaptador = new adaptadorMarca(this, R.layout.filamarca, tiendas);
setListAdapter(this.adaptador);  
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I need the values used by Tiendas to populate the array tiendasList.

Answer:

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Any of them:

Foo[] array = list.toArray(new Foo[0]);
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Or:

Foo[] array = new Foo[list.size()];
list.toArray(array); // fill the array
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Note that this only applies to arrays of reference type. For primitive arrays, use the traditional approach:

List<Integer> list = ... ; int[] array = new int[list.size()]; for(int i = 0; i < list.size(); i++) array[i] = list.get(i);Copy the code

Update:

ToArray (new Foo[0]); Instead of list.toarray (new Foo[list.size()]); .

Check from JetBrains Intellij Idea:

There are two styles for converting collections to arrays: using a pre-sized array (such as C.toarray (new String [c.size ()])) or using an empty array (such as C.Toarray (new String [0]).

In earlier Versions of Java, pre-sized arrays were recommended because the reflection calls required to create an appropriately sized array were very slow. However, because OpenJDK 6 is newer, this call becomes interesting, and the empty array version performs the same, and sometimes better, than the empty size version. In addition, passing arrays of predefined sizes can be dangerous for concurrent or synchronized collections, because data contention can occur between size and toArray calls, and if the collection is simultaneously shrunk during the operation, additional null values can result at the end of the array.

This check allows a uniform pattern to be followed: use empty arrays (recommended in modern Java) or use arrays of predetermined sizes (which may be faster in older Java versions or non-Hotspot based JVMS).

Answer:

Alternatives in Java 8:

String[] strings = list.stream().toArray(String[]::new);
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Starting with Java 11:

String[] strings = list.toArray(String[]::new);
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The article translated from kgs4h5t57thfb6iyuz6dqtun5y ac4c6men2g7xr2a – stackoverflow – com. Translate. Goog/questions / 9…

String[] strings = list.stream().toarray (String[]::new)

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