Java.io.File Class in Java
The File class is Java’s representation of a file or directory pathname. Because file and directory names have different formats on different platforms, a simple string is not adequate to name them. The File class contains several methods for working with the pathname, deleting and renaming files, creating new directories, listing the contents of a directory, and determining several common attributes of files and directories.
- It is an abstract representation of files and directory pathnames.
- A pathname, whether abstract or in string form can be either absolute or relative. The parent of an abstract pathname may be obtained by invoking the getParent() method of this class.
- First of all, we should create the File class object by passing the filename or directory name to it. A file system may implement restrictions to certain operations on the actual file-system object, such as reading, writing, and executing. These restrictions are collectively known as access permissions.
- Instances of the File class are immutable; that is, once created, the abstract pathname represented by a File object will never change.
How to create a File Object?
A File object is created by passing in a string that represents the name of a file, a String, or another File object. For example,
File a = new File("/usr/local/bin/geeks");
This defines an abstract file name for the geeks file in the directory /usr/local/bin. This is an absolute abstract file name.
Constructors of File Class
- File(File parent, String child): Creates a new File instance from a parent abstract pathname and a child pathname string.
- File(String pathname): Creates a new File instance by converting the given pathname string into an abstract pathname.
- File(String parent, String child): Creates a new File instance from a parent pathname string and a child pathname string.
- File(URI uri): Creates a new File instance by converting the given file: URI into an abstract pathname.
Methods of File Class
|S. No.||Method||Description||Return Type|
|1.||canExecute()||Tests whether the application can execute the file denoted by this abstract pathname.||boolean|
|2.||canRead()||Tests whether the application can read the file denoted by this abstract pathname.||boolean|
|3.||canWrite()||Tests whether the application can modify the file denoted by this abstract pathname.||boolean|
|4.||compareTo(File pathname)||Compares two abstract pathnames lexicographically.||int|
|5.||createNewFile()||Atomically creates a new, empty file named by this abstract pathname.||boolean|
|6.||createTempFile(String prefix, String suffix)||Creates an empty file in the default temporary-file directory.||File|
|7.||delete()||Deletes the file or directory denoted by this abstract pathname.||boolean|
|8.||equals(Object obj)||Tests this abstract pathname for equality with the given object.||boolean|
|9.||exists()||Tests whether the file or directory denoted by this abstract pathname exists.||boolean|
|10.||getAbsolutePath()||Returns the absolute pathname string of this abstract pathname.||String|
|11.||list()||Returns an array of strings naming the files and directories in the directory.||String|
|12.||getFreeSpace()||Returns the number of unallocated bytes in the partition.||long|
|13.||getName()||Returns the name of the file or directory denoted by this abstract pathname.||String|
|14.||getParent()||Returns the pathname string of this abstract pathname’s parent.||String|
|15.||getParentFile()||Returns the abstract pathname of this abstract pathname’s parent.||File|
|16.||getPath()||Converts this abstract pathname into a pathname string.||String|
|17.||setReadOnly()||Marks the file or directory named so that only read operations are allowed.||boolean|
|18.||isDirectory()||Tests whether the file denoted by this pathname is a directory.||boolean|
|19.||isFile()||Tests whether the file denoted by this abstract pathname is a normal file.||boolean|
|20.||isHidden()||Tests whether the file named by this abstract pathname is a hidden file.||boolean|
|21.||length()||Returns the length of the file denoted by this abstract pathname.||long|
|22.||listFiles()||Returns an array of abstract pathnames denoting the files in the directory.||File|
|23.||mkdir()||Creates the directory named by this abstract pathname.||boolean|
|24.||renameTo(File dest)||Renames the file denoted by this abstract pathname.||boolean|
|25.||setExecutable(boolean executable)||A convenience method to set the owner’s execute permission.||boolean|
|26.||setReadable(boolean readable)||A convenience method to set the owner’s read permission.||boolean|
|27.||setReadable(boolean readable, boolean ownerOnly)||Sets the owner’s or everybody’s read permission.||boolean|
|28.||setWritable(boolean writable)||A convenience method to set the owner’s write permission.||boolean|
|29.||toString()||Returns the pathname string of this abstract pathname.||String|
|30.||toURI()||Constructs a file URI that represents this abstract pathname.||URI|
Example 1: Program to check if a file or directory physically exists or not.
File name :file.txt Path: file.txt Absolute path:C:\Users\akki\IdeaProjects\codewriting\src\file.txt Parent:null Exists :true Is writable:true Is readabletrue Is a directory:false File Size in bytes 20
Example 2: Program to display all the contents of a directory
Here we will accept a directory name from the keyboard and then display all the contents of the directory. For this purpose, list() method can be used as:
In the preceding statement, the list() method causes all the directory entries copied into the array arr. Then pass these array elements arr[i] to the File object and test them to know if they represent a file or directory.
Enter dirpath: C:\Users\akki\IdeaProjects\ Enter the dirname codewriting .idea : is a directory an1.txt : is a file codewriting.iml : is a file file.txt : is a file out : is a directory src : is a directory text : is a file No of entries in this directory 7
Related Post: FileReader and FileWriter in Java
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