How can we confirm if all the values in a Map<String, String> are empty [duplicate]

Question

I have a Map<String,String> myMap and I'd like to check if all the values in the map are empty strings (""). I found a way to confirm if all thevaluesare null: myMay.values().stream.allMatch(Objects::inNull) but I need to check if all the values are empty strings (""). Any ideas? Thanks

Answer 1

You can use the allMatch method on the map's values stream to check if all the values are empty strings. Here's one way you could do it:

if (myMap.values().stream().allMatch(value -> value.equals(""))) {
  // all the values in the map are empty strings
}

Alternatively, you could use the isEmpty method to check if a string is empty, like this:

if (myMap.values().stream().allMatch(String::isEmpty)) {
  // all the values in the map are empty strings
}

Note that both of these solutions assume that the values in the map are strings. If the values in the map could be null, you should add a null check before checking if the string is empty, like this:

if (myMap.values().stream().allMatch(value -> value != null && value.equals(""))) {
  // all the values in the map are empty strings
}

I hope this helps! Let me know if you have any other questions.

Answer 2

Alternatively, you can use static method Predicate.isEqual(), which expects a reference to the target object for equality comparison (an empty string in this case).

boolean allEmpty = myMap.values().stream().allMatch(Predicate.isEqual(""));

Answer 3

You can use allMatch(""::equals)¹, or allMatch(Strings::isNullOrEmpty)²if you want to check for strings that are either nullorempty.

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^{1""::equals is equivalent to o -&gt; "".equals(o), which is functionally equivalent to o -&gt; o.equals("") ; use whichever of these you find most readable}

^{2or a similar function from another library}