Casting Object to Array in Java

Question

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How to convert object array to string array in Java

I am receiving an Object and casting it into a String array like this:

Object values[] = (Object[])request.getSession().getAttribute("userList");
String[] tmp = new String[values.length];
for(int i = 0; i < tmp.length; ++i) {
     tmp[i] = (String) values[i];
     out.println(tmp[i]);
}

Is there any better and cleaner way to do this?

when you call setAttribute() if you are passing a String[], you can just cast directly to that instead of using an object array as a proxy — Rocky Pulley, Jan 09 '13 at 20:09

score 5 · Accepted Answer · answered Jan 09 '13 at 20:09

5

Why not directly casting?

String values[] = (String[])request.getSession().getAttribute("userList");

answered Jan 09 '13 at 20:09

Juvanis

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3

Why not? Because `java.lang.ClassCastException` perhaps? Try `String[] arr = (String[])(new Object[]{"a", "b", "c"});` – Richard JP Le Guen Jan 09 '13 at 20:14
@RichardJPLeGuen if _getAttribute()_ is returning _Object[]_ why do you still cast it to _Object[]_ ? – Juvanis Jan 09 '13 at 20:16
2

Because [the return type of `HttpSession.getAttribute(...)` is `Object`](http://docs.oracle.com/javaee/5/api/javax/servlet/http/HttpSession.html#getAttribute(java.lang.String)) not `Object[]`. – Richard JP Le Guen Jan 09 '13 at 20:20
Of note: `Object arr = (Object)(new Object[]{"a", "b", "c"});` does not throw an exception. – Richard JP Le Guen Jan 09 '13 at 20:21
@RichardJPLeGuen but our concern is _Object[] x = (Object[]) obj;_, and your example is non-sense. – Juvanis Jan 09 '13 at 20:22

Casting Object to Array in Java

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