Error message

Deprecated function: implode(): Passing glue string after array is deprecated. Swap the parameters in drupal_get_feeds() (line 394 of /home/virtwww/w_code-sampc3e_56a7b680/http/includes/common.inc).

switch/case statements without the operator "break"

String firstNumber = "1";
String numberList = "";
switch (firstNumber) {
    case "1":
        numberList = "1";
    case "2":
        numberList += "-2";
    case "3":
        numberList += "-3";
}       
//numberList = "1-2-3"