String[] value = date.split("-");
String newDate = "";
if (value.length > 2) newDate = value[2] + "/" + value[1] + "/" + value[2];

public static void main(String[] args) {
    String value = "";
    System.out.println("value  = " + value);
    System.out.println("result = " + value.replaceAll("(\d{2})/(\d{2})/(\d{4})", "$3-$2-$1"));
    value = "26/12/2014";
    System.out.println("value  = " + value);
    System.out.println("result = " + value.replaceAll("(\d{2})/(\d{2})/(\d{4})", "$3-$2-$1"));
}

value  =
result =
value  = 26/12/2014
result = 2014-12-26