Lets say we have a simple method that should concat all names of a Person collection and return the result string.
public String concantAndReturnNames(final Collection<Person> persons) {
String result = "";
for (Person person : persons) {
result += person.getName();
}
return result;
}
Is there a way to write this code with new stream API forEach function in 1 line?
The official documentation for what you want to do: https://docs.oracle.com/javase/8/docs/api/java/util/stream/Collectors.html
// Accumulate names into a List
List<String> list = people.stream().map(Person::getName).collect(Collectors.toList());
// Convert elements to strings and concatenate them, separated by commas
String joined = things.stream()
.map(Object::toString)
.collect(Collectors.joining(", "));
For your example, you would need to do this:
// Convert elements to strings and concatenate them, separated by commas
String joined = persons.stream()
.map(Person::getName) // This will call person.getName()
.collect(Collectors.joining(", "));
The argument passed to Collectors.joining is optional.
