proper way to use list to array?

public class TestClass{


private String divisions[] ={};


public void doAction(){

 Collection testArray = new ArrayList();
 // put testArr开发者_StackOverflow社区ay will data

  divisions = (String [] )  testArray.toArray(division);    //should i use this
 divisions = (String [] )  testArray.toArray(new String [] {});   //should i use this?

}

}

if i use case 1, and i call doaction multiple time, the division, something will show wrong records if i use case2, divisions will always show the correct records. is my assumption should use case 2?

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Yes, in case 1 you could have a problem with extra items on the end of division. Example: the first time you called doAction and division was set to a certain length then if the next time you called it, it needed less space, there would be extra items that did not get overwritten in the array.

However, case 2 is not all that useful because if the array you pass in (which has a length of zero in your example) is not large enough, ArrayList will just create a new array anyway.

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Case 2 is the "more correct" way to use it.

Essentially, you're telling the method what type you would like the resultant array.

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Prefer the second one only

 divisions = (String [] )  testArray.toArray(new String [] {});