FilterInputStreamInputStream

FilterInputStream is a class in the Java programming language that is part of the java.io package. It is an abstract class that serves as a base for other input stream classes that need to filter or modify the data read from an underlying input stream. The primary purpose of FilterInputStream is to provide a way to add additional functionality to an existing input stream without having to modify the original stream's code.

The class itself does not provide any specific filtering functionality; instead, it defines a protected field named "in" that holds a reference to the underlying input stream. Subclasses of FilterInputStream can override its methods to provide specific filtering behavior. For example, a subclass might override the read method to modify the data read from the underlying stream before returning it to the caller.

FilterInputStream is typically used as a base class for other input stream classes that need to filter or modify the data read from an underlying stream. For example, BufferedInputStream is a subclass of FilterInputStream that adds buffering functionality to an underlying input stream. Similarly, DataInputStream is a subclass of FilterInputStream that provides methods for reading primitive data types from an underlying input stream.

In summary, FilterInputStream is an abstract class in the Java programming language that serves as a base for other input stream classes that need to filter or modify the data read from an underlying input stream. It provides a way to add additional functionality to an existing input stream without having to modify the original stream's code.