Question

When defining an ASyncTask and it associated methods in Android there are 3 dots that appear, eg protected Long doInBackground(URL... urls)

What do the dots mean?

Answer 1

It’s not entirely the same thing. Consider the following examples

Example 1:

public String concatenateStrings(String... strings){
  StringBuffer sb = new StringBuffer();
  for( int i = 0; i < strings.length; i++ )
    sb.append( strings[i] );

  return sb.toString();
}

Example 2:

public String concatenateStrings2(String[] strings){
  StringBuffer sb = new StringBuffer();
  for( int i = 0; i < strings.length; i++ )
    sb.append( strings[i] );

  return sb.toString();
}

They’re allmost identical, right? Wrong, calling them is the big difference. The first example allows for an undefined number of strings to be added.

Example 1:

concantenateStrings("hello", "World", " I ", " can ", " add ", " so ", " many strings here" );

Example 2:

Strings[] myStrings = new Strings[7];
myStrings[0] = "Hello";
myStrings[1] = "world";
myStrings[2] = " I ";
...
myStrings[6] = " many strings here";
concatenateStrings2( myStrings );