Java in a Nutshell, 5th Edition

Name

CheckedInputStream

Synopsis

This class is a subclass of java.io.FilterInputStream; it allows a stream to be read and a checksum computed on its contents at the same time. This is useful when you want to check the integrity of a stream of data against a published checksum value. To create a CheckedInputStream, you must specify both the stream it should read and a Checksum object, such as CRC32, that implements the particular checksum algorithm you desire. The read( ) and skip( ) methods are the same as those of other input streams. As bytes are read, they are incorporated into the checksum that is being computed. The getChecksum( ) method does not return the checksum value itself, but rather the Checksum object. You must call the getValue( ) method of this object to obtain the checksum value.

Figure 16-135. java.util.zip.CheckedInputStream

public class CheckedInputStream extends java.io.FilterInputStream {
// Public Constructors
     public CheckedInputStream(java.io.InputStream in, Checksum cksum);  
// Public Instance Methods
     public Checksum getChecksum( );  
// Public Methods Overriding FilterInputStream
     public int read( ) throws java.io.IOException;  
     public int read(byte[ ] buf, int off, int len) throws java.io.IOException;  
     public long skip(long n) throws java.io.IOException;  
}