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NNTP-Posting-Date: Mon, 11 Jun 2012 02:06:57 -0500
Date: Mon, 11 Jun 2012 00:06:54 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: unchecked conversion warning.
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On 6/10/2012 9:52 PM, Broad Liyn wrote:
> 在 2012年5月30日星期三UTC+8下午9时32分43秒，（未知）写道：
>> This code compiles with an 'unchecked conversion' warning.
>> I have tried various corrections, for example casting like (Vector<Object>), but to no
>> avail.
>> What am I doing wrong?l
>> The code is the smallest demo I could make from the original application.
>>
>> import java.util.Vector;
>> public class genericsdemo
>> {
>>    private static Vector<Vector> vdata = new Vector<Vector>(); //a Vector of Vectors
>>    private static Vector<Object> vrow  = new Vector<Object>(); //a row
>>
>>    public static void main(String args[]) {
>>      vrow.add(null); //two columns in the row
>>      vrow.add(null);
>>
>>      vdata.add(vrow); //add the row to the Vector of Vectors
>>
>>      Vector vtmp = getrow(); //test
>>    }
>>
>>    private static Vector<Object> getrow() {
>>      return vdata.elementAt(0);  //warning: [unchecked] unchecked conversion
>>    }
>> }
>>
>> JensJ
> 1.vector is no longer being supported.
> 2.
>


As of JDK 7, Vector is not even deprecated.

The documentation,
http://docs.oracle.com/javase/7/docs/api/java/util/Vector.html, says "If
a thread-safe implementation is not needed, it is recommended to use
ArrayList in place of Vector." which implies that Vector might be a
reasonable choice if thread safety is needed.

Personally, I prefer to use ArrayList as base, and wrap using
Collections.synchronizedCollection, but that is not mandatory.

Patricia