Вы также можете попробовать:
String test = "https://www.google.com/https://www.yahoo.com/https://facebook.com/";
String[] urls = test.split("(?<!/)/(?!/)");
for(String s:urls){
System.out.println(s);
}
Выход
https://www.google.com
https://www.yahoo.com
https://facebook.com