What are these three dots in parameter types

Question

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What is the ellipsis for in this method signature?

For example: protected void onProgressUpdate(Context... values)

Answer 1

One word: varargs.

The three periods after the final parameter's type indicate that the final argument may be passed as an array or as a sequence of arguments. Varargs can be used only in the final argument position.

Answer 2

They're called varargs, and were introduced in Java 5. Read http://download.oracle.com/javase/1.5.0/docs/guide/language/varargs.html for more information.

In short, it allows passing an array to a method without having to create one, as if the method took a variable number of arguments. In your example, the following four calls would be valid :

onProgressUpdate();
onProgressUpdate(context1);
onProgressUpdate(context1, context2, context3);
onProgressUpdate(new Context[] {context1, context2});

Answer 3

Its the varargs introduced in java 5. more info at Varargs

Answer 4

Three dots are called ellipsis. Method can be called any number of values of type Context. You can call that method with no value also.

Answer 5

It means that the values argument is an optional array of Context objects. So you could call the "onProgressUpdate" function in the following ways:

onProgressUpdate(); // values is an empty array.
onProgressUpdate(new Context[] { new Context() }); // values has one item.
onProgressUpdate(context1, context2); // values has two items.

See the varargs language feature introduced in Java 1.5.

Answer 6

That means that you can put a range of values :

onProgessUpdate(c1,c2,c3);