How to clear a file in java

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 can I clear the contents of a text file using Java?

All you have to do is open file in truncate mode. Any Java file out class will automatically do that for you.

How do I make a file empty?

5 Ways to Empty or Delete a Large File Content in Linux

  1. Empty File Content by Redirecting to Null. …
  2. Empty File Using ‘true’ Command Redirection. …
  3. Empty File Using cat/cp/dd utilities with /dev/null. …
  4. Empty File Using echo Command. …
  5. Empty File Using truncate Command.

How do you replace a specific line in a file using Java?

Invoke the replaceAll() method on the obtained string passing the line to be replaced (old line) and replacement line (new line) as parameters. Instantiate the FileWriter class. Add the results of the replaceAll() method the FileWriter object using the append() method.

Does file exist Java?

File exists() method in Java with examples

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.

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. txt.

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How can we remove the text from the file?

Step by step descriptive logic to remove a word from text file.

  1. Open source file in r (read) mode. …
  2. Create and open a temporary file say delete. …
  3. Read word to remove from user in some variable say toRemove .
  4. Read a line from source file fPtr and store it in temporary buffer variable.

What is flush () in Java?

The flush() method of PrintWriter Class in Java is used to flush the stream. By flushing the stream, it means to clear the stream of any element that may be or maybe not inside the stream. It neither accepts any parameter nor returns any value.

How do I change the content of a text file in Java?

Step 1 : Create a File object by passing the path of the file to be modified. Step 2 : Initialize oldContent with an empty string. This String object will hold all the old content of the input text file. Step 3 : Create BufferedReader object to read the input text file line by line.

What is an empty file?

A zero-byte file or zero-length file is a computer file containing no data; that is, it has a length or size of zero bytes. … There are many ways that could manually create a zero-byte file, for example, saving empty content in a text editor, using utilities provided by operating systems, or programming to create it.

How do I change a file type?

Convert to a different file format

  1. Click Save As…. The Save Image window will pop up.
  2. In the name field, change the file extension to the file format you want to convert your image to. The file extension is the part of the file name after the period. …
  3. Click Save, and a new file will be saved in the new format.
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How do you make a zero byte file?

Method 1

  1. Open an elevated command prompt (run as administrator).
  2. Type the following lines in the command prompt: CDWindows. COPY CON MSJAVA.DLL.
  3. After hitting enter, you’ll just a blinking cursor. Just press F6 and enter, and your zero-byte file will be created.

How do I change the first line of a file in Java?

First use BufferedReader ‘s readLine() to read the first line. Modify it and write it to the BufferedWriter . Then use a char[] array to perform a brute-force copy of the remainder of the file. This will be more efficient than doing the copy line by line.

How do you read a file and write to another file in Java?

In this tutorial we will see how to copy the content of one file to another file in java. In order to copy the file, first we can read the file using FileInputStream and then we can write the read content to the output file using FileOutputStream.

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