How do you check if a file exists in a directory in Java?

Asked By: Mohammadine Windhaus | Last Updated: 4th May, 2020
Category: technology and computing programming languages
4.8/5 (321 Views . 28 Votes)
To test to see if a file or directory exists, use the exists method of the Java File class, as shown in this example: File tmpDir = new File("/var/tmp"); boolean exists = tmpDir. exists(); The exists method of the Java File class returns true if the file or directory exists, and false otherwise.

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Similarly, you may ask, how do you check if file does not exist in Java?

The exists() method returns true if the file exist whereas notExists() method returns true when file does not exist. If both exists() and notExists() return false, the existence of the file cannot be verified. This can happen when the program does not have access to the file.

Likewise, how do I check if a file exists or not in Unix shell script?

  1. In Bash, you can use the test command to check whether a file exists and determine the type of the file.
  2. When checking if a file exists, the most commonly used FILE operators are -e and -f .
  3. If you want to perform a different action based on whether the file exists or not simply use the if/then construct:

Hereof, is file exist in Java?

The exists() function is a part of File class in Java . This function determines whether the is a file or directory denoted by the abstract filename exists or not. The function returns true if the abstract file path exists or else returns false. Parameters: This method does not accept any parameter.

What is file in Java?

Java - File Class. Advertisements. Java File class represents the files and directory pathnames in an abstract manner. This class is used for creation of files and directories, file searching, file deletion, etc. The File object represents the actual file/directory on the disk.

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How do you check Java is there or not?

Press the Start Button. Scroll down the application list to J. Open the Java folder. Click About Java.

3.1. Windows 10
  1. In the Search bar, type Control Panel.
  2. Click Programs.
  3. If the Java icon present, then Java is installed.
  4. If not, click Programs and Features, and look for installed versions of Java in the J's.

Does FileOutputStream create a new file?

FileOutputStream(File file) : Creates a file output stream to write to the file represented by specified file object. If the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason then a FileNotFoundException is thrown.

What is file not found exception in Java?

public class FileNotFoundException extends IOException. Signals that an attempt to open the file denoted by a specified pathname has failed. This exception will be thrown by the FileInputStream , FileOutputStream , and RandomAccessFile constructors when a file with the specified pathname does not exist.

How do you delete a file in Java?

In Java, we can delete a file by using the File. delete() method of File class. The delete() method deletes the file or directory denoted by the abstract pathname. If the pathname is a directory, that directory must be empty to delete.

How do you exit Java?


exit(0) : Generally used to indicate successful termination. exit(1) or exit(-1) or any other non-zero value – Generally indicates unsuccessful termination. Note : This method does not return any value. The following example shows the usage of java.

How do you write to a file in Java?

FileWriter: FileWriter is the simplest way to write a file in Java. It provides overloaded write method to write int, byte array, and String to the File. You can also write part of the String or byte array using FileWriter. FileWriter writes directly into Files and should be used only when the number of writes is less.

How do you change a filename in Java?

To rename a file, we invoke the method renameTo() on two objects of type File that represent respectively the file to rename, and the new name to give to the file. The file oldname. txt, if it exists, is renamed to the file newname.

How do I read a csv file in Java?

Reading and Writing CSVs in Core Java
  1. Use FileReader to open the CSV file.
  2. Create a BufferedReader and read the file line by line until an "End of File" (EOF) character is reached.
  3. Use the String. split() method to identify the comma delimiter and split the row into fields.

How do you create a file if it does not exist in Java?

Java creating file with File
The File's createNewFile() method creates a new, empty file named by the pathname if a file with this name does not yet exist. The createNewFile() returns true if the named file does not exist and was successfully created; false if the named file already exists.

How do you check if a file is being used by another process in Linux?


Another approach I can think of is to use lsof | grep filename. tar. gz to check if the file is being accessed by another process. You can't easily tell if it's in the process of being written to, but if it is being written to, it MUST be open.

Which class do you use to write data into a text file?

File handling in Java using FileWriter and FileReader. Java FileWriter and FileReader classes are used to write and read data from text files (they are Character Stream classes).

How do you throw an exception in Java?

Throwing an exception is as simple as using the "throw" statement. You then specify the Exception object you wish to throw. Every Exception includes a message which is a human-readable error description. It can often be related to problems with user input, server, backend, etc.

Does exist in PHP?

The file_exists() function in PHP is an inbuilt function which is used to check whether a file or directory exists or not. It specifies the path of the file or directory you want to check. Return Value: It returns True on success and False on failure.

What is [email protected] in bash?

bash filename runs the commands saved in a file. [email protected] refers to all of a shell script's command-line arguments. $1 , $2 , etc., refer to the first command-line argument, the second command-line argument, etc. Letting users decide what files to process is more flexible and more consistent with built-in Unix commands.

How do I find a file in Linux?


How to Find Files and Folders in Linux Using the Command Line
  1. Most people use a graphical file manager to find files in Linux, such as Nautilus in Gnome, Dolphin in KDE, and Thunar in Xfce.
  2. Using the Find Command.
  3. To find files that match a specific pattern, use the -name argument.
  4. If find doesn't locate any files matching your criteria, it produces no output.

What is a regular file?

A regular file is one type of file that may be stored in a file system. It is called "regular" primarily to distinguish it from other special types of files. Most files used directly by a human user are regular files. For example, executable files, text files, and image files are regular files.

What does mean in bash?

Bash is a command language interpreter. It is widely available on various operating systems and is a default command interpreter on most GNU/Linux systems. The name is an acronym for the 'Bourne-Again SHell'. Shell. Shell is a macro processor which allows for an interactive or non-interactive command execution.