jshell> File foo = new File("goblins")
foo ==> goblins

jshell> foo.exists()
$2 ==> false

jshell> foo.mkdir()
$3 ==> true

jshell> foo.exists()
$4 ==> true

jshell> foo.isDirectory()
$5 ==> true

jshell> foo.renameTo("quackery");
|  Error:
|  incompatible types: java.lang.String cannot be converted to java.io.File
|  foo.renameTo("quackery");
|               ^--------^

jshell> foo.renameTo(new File("quackery"));
$6 ==> true

jshell> ".".listFiles()
|  Error:
|  cannot find symbol
|    symbol:   method listFiles()
|  ".".listFiles()
|  ^-----------^

jshell> (new File(".")).listFiles()
$7 ==> File[9] { ./heffalump, ./ferret, ./quackery, ./bonobo, ./dingo, ./ShowRegular.java, ./carical, ./aardvark, ./elephant }

jshell> (new File(".")).URI()
|  Error:
|  cannot find symbol
|    symbol:   method URI()
|  (new File(".")).URI()
|  ^-----------------^

jshell> (new File(".")).toURI()
$8 ==> file:/Users/morrison/20202021/T1/4240/javaFIOB/./

jshell>