Is a variable length argument treated as an array in Java?

Question

As I understand an `array` consists of fixed number of elements and a `variable length argument` takes as many number of arguments as you pass (of the same type). But are they same? Can I pass one where the other is expected?

Accepted Answer

Yes, if you have a method with a varargs parameter like this:

```
public void foo(String... names)
```

and you call it like this:

```
foo("x", "y", "z");
```

then the compiler just converts that into:

```
foo(new String[] { "x", "y", "z"});
```

The type of the `names` parameter is `String[]`, and can be used just like any other array variable. Note that it could still be `null`:

```
String[] nullNames = null;
foo(nullNames);
```

See the documentation for varargs for more information.

This does not mean that varargs are interchangeable with arrays - you still need to declare the method to accept varargs. For example, if your method were declared as:

```
public void foo(String[] names)
```

then the first way of calling it would not compile.

Is a variable length argument treated as an array in Java?

Solution

Problem