What are the 3 dots in parameters?/What is a variable arity (...) parameter? [duplicate]
Its called Variable arguments or in short var-args, introduced in Java 1.5.The advantage is you can pass any number of arguments while calling the method.
For instance:
public void method1(boolean... arguments) throws Exception { for(boolean b: arguments){ // iterate over the var-args to get the arguments. System.out.println(b); } }The above method can accept all the below method calls.
method1(true);method1(true, false);method1(true, false, false);
As per other answer, it's a "varargs" parameter. Which is an array.
What many people don't realise is two important points:
- you may call the method with no parameters:
method1(); - when you do, the parameter is an empty array
Many people assume it will be null if you specify no parameters, but null checking is unnecessary.
You can force a null to be passed by calling it like this:
method1((boolean[])null);But I say if someone does this, let it explode.