Return from HashMap<String, String> when no key

What does a HashMap<String,String> return when I call map.get("key") and I don't have an entry with the key "key" in the HashMap?

Solution 1:

It returns null. It's written in the documentation.

Returns: the value to which the specified key is mapped, or null if this map contains no mapping for the key

The first thing to do when you have such a specific question is to consult the documentation. Java APIs are documented reasonably well and tell you what is returned, what exceptions are thrown and what each argument means.

Solution 2:

You can:

Check in your IDE

Map<String, String> map = new HashMap<String, String>();
map.put("foo", "fooValue");
System.out.println(map.get("bar")); // null

Check documentation - HashMap get() method description:

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.