Java ObjectInputStream readFully() Method

The readFully() method of ObjectInputStream class is used to read bytes until all the bytes in the objectinputstream are completely read. It takes 3 parameters as the buffer to which the data is stored , from where to start reading, and how many bytes to read.

Syntax

public void readFully(byte[] buf) throws IOException
public void readFully(byte[] buf, int off, int len) throws IOException

Parameter

buf - the buffer into which the data is read

off - the start offset into the data array buf

len - the maximum number of bytes to read

Returns

Throws

NullPointerException - If buf is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than buf.length - off.

EOFException - If end of file is reached.

IOException - If other I/O error has occurred.

Example 1

import java.io.*;
public class ObjectInputStreamreadFullyExample1 {
   public static void main(String[] args) {
      String s = "welcome to javatpoint";
      try {
         // create a new file with an ObjectOutputStream
         FileOutputStream outstream = new FileOutputStream("file1.txt");
         ObjectOutputStream objoutstream = new ObjectOutputStream(outstream);

         // write something in the file
         objoutstream.writeUTF(s);
         objoutstream.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream objinstream = new ObjectInputStream(new FileInputStream("file1.txt"));

         // read and print the whole content
         byte[] bt = new byte[22];
         objinstream.readFully(bt);
         String arr = new String(bt);
         System.out.println("" + arr);
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
}

Output:

welcome to javatpoint

Example 2

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class ObjectInputStreamreadFullyExample2 {
   public static void main(String[] args) throws IOException {
      String s = "welcom to javatpoint";
      
      try {
         // create a new file with an ObjectOutputStream
         FileOutputStream outstream = new FileOutputStream("file1.txt");
         ObjectOutputStream objoutstream = new ObjectOutputStream(outstream);

         // write something in the file
         objoutstream.writeUTF(s);
         objoutstream.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream objinstream = new ObjectInputStream(new FileInputStream("file1.txt"));

         // read and print the whole content
         byte[] bt = new byte[22];
        objinstream.readFully(bt, 10, 9);
        String arr = new String(bt);
         
         System.out.println("" + arr);
          
          }
       catch (Exception ex) {
         ex.printStackTrace();
      }
   }
}

Output: