Quick Answer: How does RandomAccessFile work in Java?

What is a RandomAccessFile Java?

A random access file behaves like a large array of bytes stored in the file system. There is a kind of cursor, or index into the implied array, called the file pointer; input operations read bytes starting at the file pointer and advance the file pointer past the bytes read.

How do you write a RandomAccessFile in Java?

Write Array of Bytes to a RandomAccessFile

Writing to a RandomAccessFile can be done using one it its many write() methods. Here is a simple example: RandomAccessFile file = new RandomAccessFile(“c:\data\file. txt”, “rw”); byte[] bytes = “Hello World”.

How does a random access file work?

With a sequential access file, on average you’d have to read half the zip file before finding the file that you wanted. With a random access file, you only read the directory and the file that you need.

Which method is used to position the file pointer in RandomAccessFile?

Using file pointer, we can read or write data from random access file at any position. To get the current file pointer, you can call getFilePointer() method and to set the file pointer index, you can call seek(int i) method.

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What is Java Inputstream file?

A FileInputStream obtains input bytes from a file in a file system. What files are available depends on the host environment. FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader .

How does Java NIO work?

Java NIO enables you to do non-blocking IO. For instance, a thread can ask a channel to read data into a buffer. While the channel reads data into the buffer, the thread can do something else. Once data is read into the buffer, the thread can then continue processing it.

How do I write a string in RandomAccessFile?

RandomAccessFile. writeBytes(String s) method writes the string to the file as a sequence of bytes. Each character in the string is written out, in sequence, by discarding its high eight bits. The write starts at the current position of the file pointer.

What is the advantage of a random access file?

In summary, there are 3 main advantages to random files: Random files allow you to directly access any record. Random files are usually smaller than sequential files. Random file streams can move data in both directions.

How do I read a file?

There are several ways to read a plain text file in Java e.g. you can use FileReader, BufferedReader, or Scanner to read a text file.


  1. Using BufferedReader class.
  2. Using Scanner class.
  3. Using File Reader class.
  4. Reading the whole file in a List.
  5. Read a text file as String.

How do I randomly access a file?

Random access files permit nonsequential, or random, access to a file’s contents. To access a file randomly, you open the file, seek a particular location, and read from or write to that file. This functionality is possible with the SeekableByteChannel interface.

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How a file can be randomly accessed explain C++?

Random file access is done by manipulating the file pointer using either seekg() function (for input) and seekp() function (for output). In case you are wondering, the g stands for “get” and the p for “put”.

Which function is used to access file randomly?

We learned about the functions that help us achieve random access in files, including the fseek() function, which helps us send a file pointer to a specified location; the ftell() function, which is used to find out the exact position of the file pointer with respect to the beginning; and the rewind() function, which …

Which exception is thrown by read () method?

Which exception is thrown by read() method? Explanation: read method throws IOException.

What is Java console program?

The console is the terminal window that is running the Java program. I.e., that’s the terminal window where you type in the command java ProgramName. When a Java program starts running, the Java runtime system will initialize many variables in support for the running program.

Why do we use random access in Java?

If end-of-file is reached before the desired number of byte has been read than EOFException is thrown. It is a type of IOException. Unlike IO streams that allow reading and writing data sequentially, random access file allows you to read and write a small chunk of data at any position in the file, using a file pointer.