Anyone know how to initialize an array without sizing it first?

// This works - returns a list of files and directories
File dlist = new File("C:\\");
String[] files = dlist.list();

// To get directories only:
for (int x=0;x<files.length;x++) {
  File filename = new File("C:\\"+files[x]);
  if ( filename.isDirectory()) {
             dirs[cnt++] = filename.getParent() +
filename.getName();
   }
}

But how do I initialize dirs?

// This results in uninitialized variable error
String[] dirs;

// This results in an array that is too large (causes empty lines when
sending to JComboBox)
String[] dirs = new String[20];