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Java - DataInputStream skipBytes(int n) method

Description

The Java DataInputStream skipBytes(int n) method skips over n bytes of data from the input stream. The method never throws and EOFException.

Declaration

Following is the declaration for java.io.DataInputStream.skipBytes(int n) method −

public final int skipBytes(int n)

Parameters

n − Number of bytes to be skipped.

Return Value

This method returns the number of bytes to skipped.

Exception

IOException − If the stream is closed or the or any I/O error occurs.

Example 1

The following example shows the usage of Java DataInputStream skipBytes() method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte[] buf is initialized with some byte values. A FileOutputStream object is created with a File. Then DataOutputStream is initialized with FileOutputStream object created before. Then byte array is iterated to write byte values to the dataoutputstream.

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

public class DataInputStreamDemo {
   public static void main(String[] args) throws IOException {
      InputStream is = null;
      DataInputStream dis = null;
      FileOutputStream fos = null;
      DataOutputStream dos = null;
      byte[] b = {4,124,119,114,125,45,76,83,84};
      
      try {
         // create file output stream
         fos = new FileOutputStream("F:\\test.txt");
         
         // create data output stream
         dos = new DataOutputStream(fos);
         
         // for each byte in buffer
         for(byte j:b) {
         
            // write byte to the output stream
            dos.writeByte(j);
         }
         
         // force data to the underlying stream
         dos.flush();
         
         // create file input stream
         is = new FileInputStream("F:\\test.txt");
         
         // create new data input stream
         dis = new DataInputStream(is);
         
         // available stream to be read
         while(dis.available()>0) {
         
            // reads characters encoded with modified UTF-8
            int k = dis.read();
            
            // print
            System.out.print(k+" ");
            
            // skips 1 byte
            dis.skipBytes(1);
         }
         
      } catch(Exception e) {
         // if any I/O error occurs
         e.printStackTrace();
      } finally {
         // releases all system resources from the streams
         if(is!=null)
            is.close();
         if(dos!=null)
            is.close();
         if(dis!=null)
            dis.close();
         if(fos!=null)
            fos.close();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

4 119 125 76 84

Example 2

Once byte arrays is fully written into the stream, we've flush the stream to store the values in the file. Now using FileInputStream and DataInputStream, we're reading the file written earlier. Now we're checking if DataInputStream object has data using available() method. Then using readUtf() method, we're reading every value as byte. Now as a special case, we're closing the stream before reading the values to see if this methods throw exception or not. As a result, we can see the available() method throws the exception. Finally we're closing all the streams.

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

public class DataInputStreamDemo {
   public static void main(String[] args) throws IOException {
      InputStream is = null;
      DataInputStream dis = null;
      FileOutputStream fos = null;
      DataOutputStream dos = null;
      byte[] b = {4,124,119,114,125,45,76,83,84};
      
      try {
         // create file output stream
         fos = new FileOutputStream("F:\\test.txt");
         
         // create data output stream
         dos = new DataOutputStream(fos);
         
         // for each byte in buffer
         for(byte j:b) {
         
            // write byte to the output stream
            dos.writeByte(j);
         }
         
         // force data to the underlying stream
         dos.flush();
         
         // create file input stream
         is = new FileInputStream("F:\\test.txt");
         
         // create new data input stream
         dis = new DataInputStream(is);
         // close the streams
         is.close();
         dis.close();         
         // available stream to be read
         while(dis.available()>0) {
         
            // reads characters encoded with modified UTF-8
            int k = dis.read();
            
            // print
            System.out.print(k+" ");
            
            // skips 1 byte
            dis.skipBytes(1);
         }
         
      } catch(Exception e) {
         // if any I/O error occurs
         e.printStackTrace();
      } finally {
         // releases all system resources from the streams
         if(is!=null)
            is.close();
         if(dos!=null)
            is.close();
         if(dis!=null)
            dis.close();
         if(fos!=null)
            fos.close();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

java.io.IOException: Stream Closed
	at java.base/java.io.FileInputStream.available0(Native Method)
	at java.base/java.io.FileInputStream.available(FileInputStream.java:330)
	at java.base/java.io.FilterInputStream.available(FilterInputStream.java:167)
	at DataInputStreamDemo.main(DataInputStreamDemo.java:42)

Example 3

Once byte arrays is fully written into the stream, we've flush the stream to store the values in the file. Now using FileInputStream and DataInputStream, we're reading the file written earlier. Now we're checking if DataInputStream object has data using available() method. Then using readUtf() method, we're reading every value as byte. Now as a special case, we're skipping more bytes than available and see how program behaves.

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

public class DataInputStreamDemo {
   public static void main(String[] args) throws IOException {
      InputStream is = null;
      DataInputStream dis = null;
      FileOutputStream fos = null;
      DataOutputStream dos = null;
      byte[] b = {4,124,119,114,125,45,76,83,84};
      
      try {
         // create file output stream
         fos = new FileOutputStream("F:\\test.txt");
         
         // create data output stream
         dos = new DataOutputStream(fos);
         
         // for each byte in buffer
         for(byte j:b) {
         
            // write byte to the output stream
            dos.writeByte(j);
         }
         
         // force data to the underlying stream
         dos.flush();
         
         // create file input stream
         is = new FileInputStream("F:\\test.txt");
         
         // create new data input stream
         dis = new DataInputStream(is);
         
         // available stream to be read
         while(dis.available()>0) {
         
            // reads characters encoded with modified UTF-8
            int k = dis.read();
            
            // print
            System.out.print(k+" ");
            
            // skips 3 bytes
            dis.skipBytes(3);
         }
         
      } catch(Exception e) {
         // if any I/O error occurs
         e.printStackTrace();
      } finally {
         // releases all system resources from the streams
         if(is!=null)
            is.close();
         if(dos!=null)
            is.close();
         if(dis!=null)
            dis.close();
         if(fos!=null)
            fos.close();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result −

4 125 84

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