Java : File con ejemplos
File (Java SE 22 & JDK 22) en Java con ejemplos.
Encontrará ejemplos de código en la mayoría de los métodos de File.
Advertencia :
Nota :
- Este artículo puede utilizar software de traducción para su comodidad. Consulte también la versión original en inglés.
Summary
Nota :
- La mayoría de los ejemplos de código de este artículo se ejecutan en Windows. Sin embargo, algunos de los ejemplos de código se ejecutan en Linux.
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.exists()); // false
try (final var writer = new FileWriter(file)) {
writer.write("abc");
writer.write("XYZ");
}
System.out.println(file.exists()); // true
System.out.println(file.isFile()); // true
System.out.println(file.isDirectory()); // false
// --- PowerShell ---
//PS R:\java-work> ls -Name
//aaa.txt
//
//PS R:\java-work> cat aaa.txt
//abcdXYZ
Fields
static final String pathSeparator
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
System.out.println(File.pathSeparator); // ;
System.out.println(Arrays.toString(File.pathSeparator.getBytes())); // [59]
static final char pathSeparatorChar
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
System.out.println(File.pathSeparatorChar); // ;
final int c = File.pathSeparatorChar;
System.out.println(c); // 59
static final String separator
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
System.out.println(File.separator); // \
System.out.println(Arrays.toString(File.separator.getBytes())); // [92]
static final char separatorChar
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
System.out.println(File.separatorChar); // \
final int c = File.separatorChar;
System.out.println(c); // 92
Constructors
File (File parent, String child)
final var parent = new File("R:\\java-work");
System.out.println(parent); // R:\java-work
final var file = new File(parent, "aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.exists()); // false
System.out.println(file.createNewFile()); // true
System.out.println(file.exists()); // true
File (String pathname)
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.exists()); // false
System.out.println(file.createNewFile()); // true
System.out.println(file.exists()); // true
File (String parent, String child)
final var parent = "R:\\java-work";
System.out.println(parent); // R:\java-work
final var file = new File(parent, "aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.exists()); // false
System.out.println(file.createNewFile()); // true
System.out.println(file.exists()); // true
File (URI uri)
final var uri = URI.create("file:///R:/java-work/aaa.txt");
System.out.println(uri); // file:///R:/java-work/aaa.txt
final var file = new File(uri);
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.exists()); // false
System.out.println(file.createNewFile()); // true
System.out.println(file.exists()); // true
Methods
boolean canExecute ()
// --- Linux Terminal ---
//$ touch sample1.sh
//$ ls -l sample1.sh
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.sh
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.sh");
System.out.println(file); // sample1.sh
System.out.println(file.canExecute()); // false
System.out.println(file.setExecutable(true)); // true
System.out.println(file.canExecute()); // true
// --- Linux Terminal ---
//$ ls -l sample1.sh
//-rwxrw-r-- 1 xxxx xxxx 0 ... sample1.sh
// --- Linux Terminal ---
//$ touch sample2.sh
//$ ls -l sample2.sh
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.sh
final var file = new File("sample2.sh");
System.out.println(file); // sample2.sh
System.out.println(file.canExecute()); // false
System.out.println(file.setExecutable(true, false)); // true
System.out.println(file.canExecute()); // true
// --- Linux Terminal ---
//$ ls -l sample2.sh
//-rwxrwxr-x 1 xxxx xxxx 0 ... sample2.sh
boolean canRead ()
// --- Linux Terminal ---
//$ touch sample1.txt
//$ ls -l sample1.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.txt");
System.out.println(file); // sample1.txt
System.out.println(file.canRead()); // true
System.out.println(file.setReadable(false)); // true
System.out.println(file.canRead()); // false
// --- Linux Terminal ---
//$ ls -l sample1.txt
//--w-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
// --- Linux Terminal ---
//$ touch sample2.txt
//$ ls -l sample2.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.txt
final var file = new File("sample2.txt");
System.out.println(file); // sample2.txt
System.out.println(file.canRead()); // true
System.out.println(file.setReadable(false, false)); // true
System.out.println(file.canRead()); // false
// --- Linux Terminal ---
//$ ls -l sample2.txt
//--w--w---- 1 xxxx xxxx 0 ... sample2.txt
boolean canWrite ()
// --- Linux Terminal ---
//$ touch sample1.txt
//$ ls -l sample1.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.txt");
System.out.println(file); // sample1.txt
System.out.println(file.canWrite()); // true
System.out.println(file.setWritable(false)); // true
System.out.println(file.canWrite()); // false
// --- Linux Terminal ---
//$ ls -l sample1.txt
//-r--rw-r-- 1 xxxx xxxx 0 ... sample1.txt
// --- Linux Terminal ---
//$ touch sample2.txt
//$ ls -l sample2.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.txt
final var file = new File("sample2.txt");
System.out.println(file); // sample2.txt
System.out.println(file.canWrite()); // true
System.out.println(file.setWritable(false, false)); // true
System.out.println(file.canWrite()); // false
// --- Linux Terminal ---
//$ ls -l sample2.txt
//-r--r--r-- 1 xxxx xxxx 0 ... sample2.txt
int compareTo (File pathname)
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
// A path name on Windows is not case-sensitive.
final var file1 = new File("aaa.txt");
final var file2 = new File("AAA.txt");
System.out.println(file1); // aaa.txt
System.out.println(file2); // AAA.txt
System.out.println(file1.compareTo(file2)); // 0
final var file1 = new File("aaa.txt");
final var file2 = new File("bbb.txt");
System.out.println(file1); // aaa.txt
System.out.println(file2); // bbb.txt
System.out.println(file1.compareTo(file2)); // -1
System.out.println(file2.compareTo(file1)); // 1
boolean createNewFile ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.exists()); // false
System.out.println(file.createNewFile()); // true
System.out.println(file.exists()); // true
System.out.println(file.createNewFile()); // false
static File createTempFile (String prefix, String suffix)
final var ret1 = File.createTempFile("prefix-", "-suffix");
// C:\Users\xxx\AppData\Local\Temp\prefix-1788635824849128964-suffix
System.out.println(ret1);
final var ret2 = File.createTempFile("abcd-", ".txt");
// C:\Users\xxx\AppData\Local\Temp\abcd-2471973508160575501.txt
System.out.println(ret2);
final var ret3 = File.createTempFile("prefix-", null);
// C:\Users\xxx\AppData\Local\Temp\prefix-4955106351488410780.tmp
System.out.println(ret3);
static File createTempFile (String prefix, String suffix, File directory)
final var dir = new File("R:\\java-work");
System.out.println(dir); // R:\java-work
System.out.println(dir.isDirectory()); // true
final var ret1 = File.createTempFile("prefix-", "-suffix", dir);
System.out.println(ret1); // R:\java-work\prefix-11985693266629058833-suffix
final var ret2 = File.createTempFile("abcd-", ".txt", dir);
System.out.println(ret2); // R:\java-work\abcd-17241334720235449415.txt
final var ret3 = File.createTempFile("prefix-", null, dir);
System.out.println(ret3); // R:\java-work\prefix-16933306792652896919.tmp
boolean delete ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
System.out.println(file.createNewFile()); // true
System.out.println(dir.mkdir()); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//d---- dir
//-a--- aaa.txt
System.out.println(file.delete()); // true
System.out.println(file.exists()); // false
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//d---- dir
System.out.println(dir.delete()); // true
System.out.println(dir.exists()); // false
// --- PowerShell ---
//PS R:\java-work> ls
//<No files / directories>
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//└─dir
// aaa.txt
// bbb.txt
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
System.out.println(dir.isDirectory()); // true
System.out.println(dir.delete()); // false
void deleteOnExit ()
public class Main {
public static void main(String[] args) throws IOException {
final var file = new File("sample.txt");
System.out.println("file = " + file);
System.out.println("file.exists = " + file.exists());
file.deleteOnExit();
System.out.println("deleteOnExit : OK!");
System.out.println("file.exists = " + file.exists());
}
}
// --- PowerShell ---
//PS R:\java-work> ls -Name
//Main.java
//sample.txt
//
//PS R:\java-work> java Main.java
//file = sample.txt
//file.exists = true
//deleteOnExit : OK!
//file.exists = true
//
//PS R:\java-work> ls -Name
//Main.java
boolean equals (Object obj)
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
// A path name on Windows is not case-sensitive.
final var file1 = new File("aaa.txt");
final var file2 = new File("AAA.txt");
System.out.println(file1); // aaa.txt
System.out.println(file2); // AAA.txt
System.out.println(file1.equals(file2)); // true
final var file1 = new File("aaa.txt");
final var file2 = new File("bbb.txt");
System.out.println(file1); // aaa.txt
System.out.println(file2); // bbb.txt
System.out.println(file1.equals(file2)); // false
System.out.println(file2.equals(file1)); // false
boolean exists ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
final var nonExistentPath = new File("R:\\java-work\\xxx");
System.out.println(nonExistentPath); // R:\java-work\xxx
System.out.println(file.createNewFile()); // true
System.out.println(dir.mkdir()); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//d---- dir
//-a--- aaa.txt
System.out.println(file.isFile()); // true
System.out.println(file.isDirectory()); // false
System.out.println(file.exists()); // true
System.out.println(dir.isFile()); // false
System.out.println(dir.isDirectory()); // true
System.out.println(dir.exists()); // true
System.out.println(nonExistentPath.isFile()); // false
System.out.println(nonExistentPath.isDirectory()); // false
System.out.println(nonExistentPath.exists()); // false
File getAbsoluteFile ()
public class Main {
public static void main(String[] args) throws IOException {
final var userDir = System.getProperty("user.dir");
System.out.println("user.dir = " + userDir);
{
final var file = new File("aaa.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("isAbsolute = " + file.isAbsolute());
System.out.println("getAbsoluteFile = " + file.getAbsoluteFile());
System.out.println("getAbsolutePath = " + file.getAbsolutePath());
}
{
final var file = new File("R:\\java-work\\bbb.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("isAbsolute = " + file.isAbsolute());
System.out.println("getAbsoluteFile = " + file.getAbsoluteFile());
System.out.println("getAbsolutePath = " + file.getAbsolutePath());
}
}
}
// --- PowerShell ---
//PS R:\java-work> java Main.java
//user.dir = R:\java-work
//------
//file = aaa.txt
//isAbsolute = false
//getAbsoluteFile = R:\java-work\aaa.txt
//getAbsolutePath = R:\java-work\aaa.txt
//------
//file = R:\java-work\bbb.txt
//isAbsolute = true
//getAbsoluteFile = R:\java-work\bbb.txt
//getAbsolutePath = R:\java-work\bbb.txt
String getAbsolutePath ()
public class Main {
public static void main(String[] args) throws IOException {
final var userDir = System.getProperty("user.dir");
System.out.println("user.dir = " + userDir);
{
final var file = new File("aaa.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("isAbsolute = " + file.isAbsolute());
System.out.println("getAbsoluteFile = " + file.getAbsoluteFile());
System.out.println("getAbsolutePath = " + file.getAbsolutePath());
}
{
final var file = new File("R:\\java-work\\bbb.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("isAbsolute = " + file.isAbsolute());
System.out.println("getAbsoluteFile = " + file.getAbsoluteFile());
System.out.println("getAbsolutePath = " + file.getAbsolutePath());
}
}
}
// --- PowerShell ---
//PS R:\java-work> java Main.java
//user.dir = R:\java-work
//------
//file = aaa.txt
//isAbsolute = false
//getAbsoluteFile = R:\java-work\aaa.txt
//getAbsolutePath = R:\java-work\aaa.txt
//------
//file = R:\java-work\bbb.txt
//isAbsolute = true
//getAbsoluteFile = R:\java-work\bbb.txt
//getAbsolutePath = R:\java-work\bbb.txt
File getCanonicalFile ()
public class Main {
public static void main(String[] args) throws IOException {
final var userDir = System.getProperty("user.dir");
System.out.println("user.dir = " + userDir);
{
final var file = new File("dir\\aaa.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("getCanonicalFile = " + file.getCanonicalFile());
System.out.println("getCanonicalPath = " + file.getCanonicalPath());
}
{
final var file = new File("dir\\..\\bbb.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("getCanonicalFile = " + file.getCanonicalFile());
System.out.println("getCanonicalPath = " + file.getCanonicalPath());
}
}
}
// --- PowerShell ---
//PS R:\java-work> java Main.java
//user.dir = R:\java-work
//------
//file = dir\aaa.txt
//getCanonicalFile = R:\java-work\dir\aaa.txt
//getCanonicalPath = R:\java-work\dir\aaa.txt
//------
//file = dir\..\bbb.txt
//getCanonicalFile = R:\java-work\bbb.txt
//getCanonicalPath = R:\java-work\bbb.txt
String getCanonicalPath ()
public class Main {
public static void main(String[] args) throws IOException {
final var userDir = System.getProperty("user.dir");
System.out.println("user.dir = " + userDir);
{
final var file = new File("dir\\aaa.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("getCanonicalFile = " + file.getCanonicalFile());
System.out.println("getCanonicalPath = " + file.getCanonicalPath());
}
{
final var file = new File("dir\\..\\bbb.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("getCanonicalFile = " + file.getCanonicalFile());
System.out.println("getCanonicalPath = " + file.getCanonicalPath());
}
}
}
// --- PowerShell ---
//PS R:\java-work> java Main.java
//user.dir = R:\java-work
//------
//file = dir\aaa.txt
//getCanonicalFile = R:\java-work\dir\aaa.txt
//getCanonicalPath = R:\java-work\dir\aaa.txt
//------
//file = dir\..\bbb.txt
//getCanonicalFile = R:\java-work\bbb.txt
//getCanonicalPath = R:\java-work\bbb.txt
long getFreeSpace ()
final var file = new File("D:");
System.out.println(file); // D:
// --- PowerShell ---
//PS R:\java-work> Get-PSDrive D
//
//Name Used (GB) Free (GB) Provider Root ...
//---- --------- --------- -------- ---- ...
//D 1665.41 197.48 FileSystem D:\ ...
System.out.println(file.getTotalSpace()); // 2000263573504
System.out.println(file.getFreeSpace()); // 212039778304
System.out.println(file.getUsableSpace()); // 212039778304
String getName ()
final var file = new File("dir1\\dir2\\aaa.txt");
System.out.println(file.getPath()); // dir1\dir2\aaa.txt
System.out.println(file.getName()); // aaa.txt
System.out.println(file.getParent()); // dir1\dir2
String getParent ()
final var file = new File("dir1\\dir2\\aaa.txt");
System.out.println(file.getPath()); // dir1\dir2\aaa.txt
System.out.println(file.getName()); // aaa.txt
System.out.println(file.getParent()); // dir1\dir2
File getParentFile ()
final var file = new File("dir1\\dir2\\aaa.txt");
System.out.println(file); // dir1\dir2\aaa.txt
final var parent = file.getParentFile();
System.out.println(parent); // dir1\dir2
final var parentParent = parent.getParentFile();
System.out.println(parentParent); // dir1
String getPath ()
final var file = new File("dir1\\dir2\\aaa.txt");
System.out.println(file.getPath()); // dir1\dir2\aaa.txt
System.out.println(file.getName()); // aaa.txt
System.out.println(file.getParent()); // dir1\dir2
long getTotalSpace ()
final var file = new File("D:");
System.out.println(file); // D:
// --- PowerShell ---
//PS R:\java-work> Get-PSDrive D
//
//Name Used (GB) Free (GB) Provider Root ...
//---- --------- --------- -------- ---- ...
//D 1665.41 197.48 FileSystem D:\ ...
System.out.println(file.getTotalSpace()); // 2000263573504
System.out.println(file.getFreeSpace()); // 212039778304
System.out.println(file.getUsableSpace()); // 212039778304
long getUsableSpace ()
final var file = new File("D:");
System.out.println(file); // D:
// --- PowerShell ---
//PS R:\java-work> Get-PSDrive D
//
//Name Used (GB) Free (GB) Provider Root ...
//---- --------- --------- -------- ---- ...
//D 1665.41 197.48 FileSystem D:\ ...
System.out.println(file.getTotalSpace()); // 2000263573504
System.out.println(file.getFreeSpace()); // 212039778304
System.out.println(file.getUsableSpace()); // 212039778304
int hashCode ()
final var os = System.getProperty("os.name");
System.out.println(os); // Windows 10
// A path name on Windows is not case-sensitive.
final var ret1 = new File("aaa.txt").hashCode();
System.out.println(ret1); // -1239232814
final var ret2 = new File("AAA.TXT").hashCode();
System.out.println(ret2); // -1239232814
final var ret1 = new File("dir1\\dir2\\aaa.txt").hashCode();
System.out.println(ret1); // -639828267
final var ret2 = new File("R:\\java-work\\aaa.txt").hashCode();
System.out.println(ret2); // 503453694
boolean isAbsolute ()
public class Main {
public static void main(String[] args) throws IOException {
final var userDir = System.getProperty("user.dir");
System.out.println("user.dir = " + userDir);
{
final var file = new File("aaa.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("isAbsolute = " + file.isAbsolute());
System.out.println("getAbsoluteFile = " + file.getAbsoluteFile());
System.out.println("getAbsolutePath = " + file.getAbsolutePath());
}
{
final var file = new File("R:\\java-work\\bbb.txt");
System.out.println("------");
System.out.println("file = " + file);
System.out.println("isAbsolute = " + file.isAbsolute());
System.out.println("getAbsoluteFile = " + file.getAbsoluteFile());
System.out.println("getAbsolutePath = " + file.getAbsolutePath());
}
}
}
// --- PowerShell ---
//PS R:\java-work> java Main.java
//user.dir = R:\java-work
//------
//file = aaa.txt
//isAbsolute = false
//getAbsoluteFile = R:\java-work\aaa.txt
//getAbsolutePath = R:\java-work\aaa.txt
//------
//file = R:\java-work\bbb.txt
//isAbsolute = true
//getAbsoluteFile = R:\java-work\bbb.txt
//getAbsolutePath = R:\java-work\bbb.txt
boolean isDirectory ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
final var nonExistentPath = new File("R:\\java-work\\xxx");
System.out.println(nonExistentPath); // R:\java-work\xxx
System.out.println(file.createNewFile()); // true
System.out.println(dir.mkdir()); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//d---- dir
//-a--- aaa.txt
System.out.println(file.isFile()); // true
System.out.println(file.isDirectory()); // false
System.out.println(file.exists()); // true
System.out.println(dir.isFile()); // false
System.out.println(dir.isDirectory()); // true
System.out.println(dir.exists()); // true
System.out.println(nonExistentPath.isFile()); // false
System.out.println(nonExistentPath.isDirectory()); // false
System.out.println(nonExistentPath.exists()); // false
boolean isFile ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
final var nonExistentPath = new File("R:\\java-work\\xxx");
System.out.println(nonExistentPath); // R:\java-work\xxx
System.out.println(file.createNewFile()); // true
System.out.println(dir.mkdir()); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//d---- dir
//-a--- aaa.txt
System.out.println(file.isFile()); // true
System.out.println(file.isDirectory()); // false
System.out.println(file.exists()); // true
System.out.println(dir.isFile()); // false
System.out.println(dir.isDirectory()); // true
System.out.println(dir.exists()); // true
System.out.println(nonExistentPath.isFile()); // false
System.out.println(nonExistentPath.isDirectory()); // false
System.out.println(nonExistentPath.exists()); // false
boolean isHidden ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.createNewFile()); // true
System.out.println(file.isHidden()); // false
// --- PowerShell ---
//PS R:\java-work> ls -Force | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//-a--- aaa.txt
Files.setAttribute(file.toPath(), "dos:hidden", true);
System.out.println(file.isHidden()); // true
// --- PowerShell ---
//PS R:\java-work> ls -Force | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//-a-h- aaa.txt
long lastModified ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.createNewFile()); // true
final var zoneId = ZoneId.systemDefault();
System.out.println(zoneId); // Asia/Tokyo
final var dateTime1 = ZonedDateTime.of(2100, 1, 1, 0, 0, 0, 0, zoneId);
System.out.println(dateTime1); // 2100-01-01T00:00+09:00[Asia/Tokyo]
final var ret = file.setLastModified(dateTime1.toInstant().toEpochMilli());
System.out.println(ret); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property LastWriteTime, Name
//
//LastWriteTime Name
//------------- ----
//2100/01/01 0:00:00 aaa.txt
final var lastModified = file.lastModified();
System.out.println(lastModified); // 4102412400000
final var dateTime2 = ZonedDateTime.ofInstant(
Instant.ofEpochMilli(lastModified), zoneId);
System.out.println(dateTime2); // 2100-01-01T00:00+09:00[Asia/Tokyo]
long length ()
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//│ aaa.txt
//│ bbb.txt
//│
//└─dir
// ccc.txt
//
//PS R:\java-work> ls | Format-Table -Property Length, Name
//
//Length Name
//------ ----
// dir
//5 aaa.txt
//1000 bbb.txt
//
//PS R:\java-work> ls dir | Format-Table -Property Length, Name
//
//Length Name
//------ ----
// 12 ccc.txt
final var file1 = new File("R:\\java-work\\aaa.txt");
System.out.println(file1); // R:\java-work\aaa.txt
System.out.println(file1.length()); // 5
final var file2 = new File("R:\\java-work\\bbb.txt");
System.out.println(file2); // R:\java-work\bbb.txt
System.out.println(file2.length()); // 1000
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
System.out.println(dir.length()); // 0
String[] list ()
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//│ aaa.txt
//│ bbb.txt
//│
//└─dir
// ccc.txt
// ddd.txt
{
final var dir = new File("R:\\java-work");
System.out.println(dir); // R:\java-work
final var ret = dir.list();
System.out.println(Arrays.toString(ret)); // [aaa.txt, bbb.txt, dir]
}
{
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
final var ret = dir.list();
System.out.println(Arrays.toString(ret)); // [ccc.txt, ddd.txt]
}
String[] list (FilenameFilter filter)
// --- PowerShell ---
//PS R:\java-work> ls -Name
//aaa.txt
//bbb.jpg
//ccc.txt
//ddd.jpg
final var dir = new File("R:\\java-work");
System.out.println(dir); // R:\java-work
final var filter = new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
return name.endsWith(".txt");
}
};
final var ret1 = dir.list();
System.out.println(Arrays.toString(ret1)); // [aaa.txt, bbb.jpg, ccc.txt, ddd.jpg]
final var ret2 = dir.list(filter);
System.out.println(Arrays.toString(ret2)); // [aaa.txt, ccc.txt]
File[] listFiles ()
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//│ aaa.txt
//│ bbb.txt
//│
//└─dir
// ccc.txt
// ddd.txt
{
final var dir = new File("R:\\java-work");
System.out.println(dir); // R:\java-work
final var files = dir.listFiles();
if (files != null) {
System.out.println("-- listFiles --");
for (final var file : files) {
System.out.println(file);
}
}
// Result
// ↓
//-- listFiles --
//R:\java-work\aaa.txt
//R:\java-work\bbb.txt
//R:\java-work\dir
}
{
final var dir = new File("R:\\java-work\\dir");
System.out.println(dir); // R:\java-work\dir
final var files = dir.listFiles();
if (files != null) {
System.out.println("-- listFiles --");
for (final var file : files) {
System.out.println(file);
}
}
// Result
// ↓
//-- listFiles --
//R:\java-work\dir\ccc.txt
//R:\java-work\dir\ddd.txt
}
File[] listFiles (FileFilter filter)
// --- PowerShell ---
//PS R:\java-work> ls -Name
//aaa.txt
//bbb.jpg
//ccc.txt
//ddd.jpg
final var dir = new File("R:\\java-work");
System.out.println(dir); // R:\java-work
final var filter = new FileFilter() {
@Override
public boolean accept(File pathname) {
return pathname.getName().endsWith(".txt");
}
};
final var files = dir.listFiles(filter);
if (files != null) {
System.out.println("-- listFiles --");
for (final var file : files) {
System.out.println(file);
}
}
// Result
// ↓
//-- listFiles --
//R:\java-work\aaa.txt
//R:\java-work\ccc.txt
File[] listFiles (FilenameFilter filter)
// --- PowerShell ---
//PS R:\java-work> ls -Name
//aaa.txt
//bbb.jpg
//ccc.txt
//ddd.jpg
final var dir = new File("R:\\java-work");
System.out.println(dir); // R:\java-work
final var filter = new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
return name.endsWith(".txt");
}
};
final var files = dir.listFiles(filter);
if (files != null) {
System.out.println("-- listFiles --");
for (final var file : files) {
System.out.println(file);
}
}
// Result
// ↓
//-- listFiles --
//R:\java-work\aaa.txt
//R:\java-work\ccc.txt
static File[] listRoots ()
final var roots = File.listRoots();
for (final var root : roots) {
System.out.println(root);
}
// Result
// ↓
//C:\
//D:\
//...
boolean mkdir ()
// --- PowerShell ---
//PS R:\java-work> ls -Name
//<No files / directories>
final var dir1 = new File("R:\\java-work\\dir1");
System.out.println(dir1); // R:\java-work\dir1
System.out.println(dir1.mkdir()); // true
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//└─dir1
final var dir2 = new File(dir1, "dir2");
System.out.println(dir2); // R:\java-work\dir1\dir2
System.out.println(dir2.mkdir()); // true
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//└─dir1
// └─dir2
// --- PowerShell ---
//PS R:\java-work> ls -Name
//<No files / directories>
final var dir = new File("R:\\java-work\\dir1\\dir2");
System.out.println(dir); // R:\java-work\dir1\dir2
System.out.println(dir.mkdir()); // false
// --- PowerShell ---
//PS R:\java-work> ls -Name
//<No files / directories>
boolean mkdirs ()
// --- PowerShell ---
//PS R:\java-work> ls -Name
//<No files / directories>
final var dir = new File("R:\\java-work\\dir1\\dir2");
System.out.println(dir); // R:\java-work\dir1\dir2
System.out.println(dir.mkdirs()); // true
// --- PowerShell ---
//PS R:\java-work> tree /F
//...
//R:.
//└─dir1
// └─dir2
boolean renameTo (File dest)
final var src = new File("R:\\java-work\\src.txt");
System.out.println(src); // R:\java-work\src.txt
final var dst = new File("R:\\java-work\\dst.txt");
System.out.println(dst); // R:\java-work\dst.txt
System.out.println(src.exists()); // true
System.out.println(dst.exists()); // false
// --- PowerShell ---
//PS R:\java-work> ls -Name
//src.txt
//PS R:\java-work> cat src.txt
//abcd
System.out.println(src.renameTo(dst)); // true
System.out.println(src.exists()); // false
System.out.println(dst.exists()); // true
// --- PowerShell ---
//PS R:\java-work> ls -Name
//dst.txt
//PS R:\java-work> cat dst.txt
//abcd
boolean setExecutable (boolean executable)
// --- Linux Terminal ---
//$ touch sample1.sh
//$ ls -l sample1.sh
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.sh
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.sh");
System.out.println(file); // sample1.sh
System.out.println(file.canExecute()); // false
System.out.println(file.setExecutable(true)); // true
System.out.println(file.canExecute()); // true
// --- Linux Terminal ---
//$ ls -l sample1.sh
//-rwxrw-r-- 1 xxxx xxxx 0 ... sample1.sh
// --- Linux Terminal ---
//$ touch sample2.sh
//$ ls -l sample2.sh
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.sh
final var file = new File("sample2.sh");
System.out.println(file); // sample2.sh
System.out.println(file.canExecute()); // false
System.out.println(file.setExecutable(true, false)); // true
System.out.println(file.canExecute()); // true
// --- Linux Terminal ---
//$ ls -l sample2.sh
//-rwxrwxr-x 1 xxxx xxxx 0 ... sample2.sh
boolean setExecutable (boolean executable, boolean ownerOnly)
// --- Linux Terminal ---
//$ touch sample1.sh
//$ ls -l sample1.sh
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.sh
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.sh");
System.out.println(file); // sample1.sh
System.out.println(file.canExecute()); // false
System.out.println(file.setExecutable(true)); // true
System.out.println(file.canExecute()); // true
// --- Linux Terminal ---
//$ ls -l sample1.sh
//-rwxrw-r-- 1 xxxx xxxx 0 ... sample1.sh
// --- Linux Terminal ---
//$ touch sample2.sh
//$ ls -l sample2.sh
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.sh
final var file = new File("sample2.sh");
System.out.println(file); // sample2.sh
System.out.println(file.canExecute()); // false
System.out.println(file.setExecutable(true, false)); // true
System.out.println(file.canExecute()); // true
// --- Linux Terminal ---
//$ ls -l sample2.sh
//-rwxrwxr-x 1 xxxx xxxx 0 ... sample2.sh
boolean setLastModified (long time)
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.createNewFile()); // true
final var zoneId = ZoneId.systemDefault();
System.out.println(zoneId); // Asia/Tokyo
final var dateTime1 = ZonedDateTime.of(2100, 1, 1, 0, 0, 0, 0, zoneId);
System.out.println(dateTime1); // 2100-01-01T00:00+09:00[Asia/Tokyo]
final var ret = file.setLastModified(dateTime1.toInstant().toEpochMilli());
System.out.println(ret); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property LastWriteTime, Name
//
//LastWriteTime Name
//------------- ----
//2100/01/01 0:00:00 aaa.txt
final var lastModified = file.lastModified();
System.out.println(lastModified); // 4102412400000
final var dateTime2 = ZonedDateTime.ofInstant(
Instant.ofEpochMilli(lastModified), zoneId);
System.out.println(dateTime2); // 2100-01-01T00:00+09:00[Asia/Tokyo]
boolean setReadable (boolean readable)
// --- Linux Terminal ---
//$ touch sample1.txt
//$ ls -l sample1.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.txt");
System.out.println(file); // sample1.txt
System.out.println(file.canRead()); // true
System.out.println(file.setReadable(false)); // true
System.out.println(file.canRead()); // false
// --- Linux Terminal ---
//$ ls -l sample1.txt
//--w-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
// --- Linux Terminal ---
//$ touch sample2.txt
//$ ls -l sample2.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.txt
final var file = new File("sample2.txt");
System.out.println(file); // sample2.txt
System.out.println(file.canRead()); // true
System.out.println(file.setReadable(false, false)); // true
System.out.println(file.canRead()); // false
// --- Linux Terminal ---
//$ ls -l sample2.txt
//--w--w---- 1 xxxx xxxx 0 ... sample2.txt
boolean setReadable (boolean readable, boolean ownerOnly)
// --- Linux Terminal ---
//$ touch sample1.txt
//$ ls -l sample1.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.txt");
System.out.println(file); // sample1.txt
System.out.println(file.canRead()); // true
System.out.println(file.setReadable(false)); // true
System.out.println(file.canRead()); // false
// --- Linux Terminal ---
//$ ls -l sample1.txt
//--w-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
// --- Linux Terminal ---
//$ touch sample2.txt
//$ ls -l sample2.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.txt
final var file = new File("sample2.txt");
System.out.println(file); // sample2.txt
System.out.println(file.canRead()); // true
System.out.println(file.setReadable(false, false)); // true
System.out.println(file.canRead()); // false
// --- Linux Terminal ---
//$ ls -l sample2.txt
//--w--w---- 1 xxxx xxxx 0 ... sample2.txt
boolean setReadOnly ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
System.out.println(file.createNewFile()); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//-a--- aaa.txt
System.out.println(file.setReadOnly()); // true
// --- PowerShell ---
//PS R:\java-work> ls | Format-Table -Property Mode, Name
//
//Mode Name
//---- ----
//-ar-- aaa.txt
boolean setWritable (boolean writable)
// --- Linux Terminal ---
//$ touch sample1.txt
//$ ls -l sample1.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.txt");
System.out.println(file); // sample1.txt
System.out.println(file.canWrite()); // true
System.out.println(file.setWritable(false)); // true
System.out.println(file.canWrite()); // false
// --- Linux Terminal ---
//$ ls -l sample1.txt
//-r--rw-r-- 1 xxxx xxxx 0 ... sample1.txt
// --- Linux Terminal ---
//$ touch sample2.txt
//$ ls -l sample2.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.txt
final var file = new File("sample2.txt");
System.out.println(file); // sample2.txt
System.out.println(file.canWrite()); // true
System.out.println(file.setWritable(false, false)); // true
System.out.println(file.canWrite()); // false
// --- Linux Terminal ---
//$ ls -l sample2.txt
//-r--r--r-- 1 xxxx xxxx 0 ... sample2.txt
boolean setWritable (boolean writable, boolean ownerOnly)
// --- Linux Terminal ---
//$ touch sample1.txt
//$ ls -l sample1.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample1.txt
final var os = System.getProperty("os.name");
System.out.println(os); // Linux
final var file = new File("sample1.txt");
System.out.println(file); // sample1.txt
System.out.println(file.canWrite()); // true
System.out.println(file.setWritable(false)); // true
System.out.println(file.canWrite()); // false
// --- Linux Terminal ---
//$ ls -l sample1.txt
//-r--rw-r-- 1 xxxx xxxx 0 ... sample1.txt
// --- Linux Terminal ---
//$ touch sample2.txt
//$ ls -l sample2.txt
//-rw-rw-r-- 1 xxxx xxxx 0 ... sample2.txt
final var file = new File("sample2.txt");
System.out.println(file); // sample2.txt
System.out.println(file.canWrite()); // true
System.out.println(file.setWritable(false, false)); // true
System.out.println(file.canWrite()); // false
// --- Linux Terminal ---
//$ ls -l sample2.txt
//-r--r--r-- 1 xxxx xxxx 0 ... sample2.txt
Path toPath ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
final var path = file.toPath();
System.out.println(path); // R:\java-work\aaa.txt
Files.writeString(path, "abcd");
// --- PowerShell ---
//PS R:\java-work> ls -Name
//aaa.txt
//PS R:\java-work> cat aaa.txt
//abcd
String toString ()
final var file = new File("aaa.txt");
final var str = file.toString();
System.out.println(str); // aaa.txt
final var dir = new File("R:\\java-work\\dir");
final var str = dir.toString();
System.out.println(str); // R:\java-work\dir
URI toURI ()
final var file = new File("R:\\java-work\\aaa.txt");
System.out.println(file); // R:\java-work\aaa.txt
final var uri = file.toURI();
System.out.println(uri); // file:/R:/java-work/aaa.txt
URL toURL ()
Deprecated.