String path = file.getAbsolutepash();
long len -file.length();
lastModified
DateFormat dateFormar = DateFormat.getDateTimeInstance();

boolean a = file.createNewfile();
throws IoException
boolean b = file.delete
file file = new file("n.txt");
boolean b =file.createNewfile();
throws IoException madir

boolean dir = dir.mkdir();
exsits 存在 ecsits ecsits
file a = new file("a.txt");
boolean b = file.exists(); directory
boolean a =b.exists();