When you write String::toUpperCase, Java binds each element of the stream (String object) to the toUpperCase() method. This means String::toUpperCase is interpreted as s -> s.toUpperCase(), where ...

Once created, a string using string class cannot be changed. Any attempted changes will create another string instance. Users can perform basic operations, such as comparing strings. The .equals () ...

The example code below shows how to use Java’s DirectoryStream in a method to list the files of a directory: public Set<String> listFilesUsingDirectoryStream(String dir) throws IOException { ...