Java - ByteArrayInputStream mark()

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Description

The Java ByteArrayInputStream mark(int readAheadLimit) method sets the current mark position in the stream. By default the mark ByteArrayInputStream are marked at postion 0.

Declaration

Following is the declaration for java.io.ByteArrayInputStream.mark(int readAheadLimit) method −

public void mark(int readAheadLimit)

Parameters

readLimit − This integer value for this class has no meaning.

Return Value

This method doesn't return any value.

Exception

NA

Example 1

The following example shows the usage of Java ByteArrayInputStream mark() method. We've created a variable buf as byte[] and initialized with few bytes. We've created a ByteArrayInputStream reference and then initialized it with buf variable. We're reading first three bytes using read() method and then using mark() method, we've reset the mark current position and then bytes are read again. Then we've called the reset() method to reset the head to previously marked position and bytes are read again.

package com.tutorialspoint;
import java.io.ByteArrayInputStream;
import java.io.IOException;
public class ByteArrayInputStreamDemo {
   public static void main(String[] args) throws IOException {
      byte[] buf = {65, 66, 67, 68, 69};
      ByteArrayInputStream bais = null;      
      try {
         
         // create new byte array input stream
         bais = new ByteArrayInputStream(buf);
         
         // print bytes
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());         
         System.out.println("Mark() invocation");

         // mark() invocation;
         bais.mark(0);
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());         
         System.out.println("Reset() invocation");
         
         // reset() invocation
         bais.reset();
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());         
      } catch(Exception e) {
         
         // if I/O error occurs
         e.printStackTrace();
      } finally {
         if(bais!=null)
            bais.close();
      }   
   }
}

Output

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

Byte read 65
Byte read 66
Byte read 67
Mark() invocation
Byte read 68
Byte read 69
Reset() invocation
Byte read 68
Byte read 69

Example 2

The following example shows the usage of Java ByteArrayInputStream mark() method. We've created a variable buf as byte[] and initialized with few bytes. We've created a ByteArrayInputStream reference and then initialized it with buf variable. We're reading first two bytes using read() method and then using mark() method, we've reset the mark to current position and then bytes are read again. Then we've called the reset() method to reset the head to previously marked position and bytes are read again.

package com.tutorialspoint;
import java.io.ByteArrayInputStream;
import java.io.IOException;
public class ByteArrayInputStreamDemo {
   public static void main(String[] args) throws IOException {
      byte[] buf = {65, 66, 67, 68, 69};
      ByteArrayInputStream bais = null;      
      try {
         
         // create new byte array input stream
         bais = new ByteArrayInputStream(buf);
         
         // print bytes
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());         
         System.out.println("Mark() invocation");

         // mark() invocation;
         bais.mark(0);
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());         
         System.out.println("Reset() invocation");
         
         // reset() invocation
         bais.reset();
         System.out.println("Byte read "+ bais.read());
         System.out.println("Byte read "+ bais.read());         
      } catch(Exception e) {
         
         // if I/O error occurs
         e.printStackTrace();
      } finally {
         if(bais!=null)
            bais.close();
      }   
   }
}

Output

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

Byte read 65
Byte read 66
Mark() invocation
Byte read 67
Byte read 68
Byte read 69
Reset() invocation
Byte read 67
Byte read 68