InputStream Classes
Introduction
-
InputStreamis an abstract class used to read byte-oriented data from input sources such as files, memory or network connections. -
It is present in
java.iopackage. -
It provides basic methods like
read()to read data from input sources.
-
Below is the diagram for InputStream class hierarchy:
- Each of these classes are designed for specific purposes, which are explained below one by one.
1. FileInputStream
- Description: Reads data from a file in the form of bytes.
- Use in Projects: Useful for reading binary files such as images, audio, or video.
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Example Syntax:
FileInputStream fis = new FileInputStream("file.txt"); int data = fis.read(); fis.close();
2. ByteArrayInputStream
- Description: Reads data from a byte array as an input stream.
- Use in Projects: Useful for testing, or when data is already available in memory (like byte arrays).
-
Example Syntax:
FileInputStream fis = new FileInputStream("file.txt"); int data = fis.read(); fis.close();
3. FilterInputStream
- Description: A base class for other input stream filters (not used directly).
- Use in Projects: Extended by classes like BufferedInputStream, DataInputStream, etc.
-
Example Syntax:
Rarely used directly. Mostly used via subclasses.
4. BufferedInputStream
- Description: Adds buffering to input stream for faster reading.
- Use in Projects: Useful when reading large files (improves performance).
-
Example Syntax:
BufferedInputStream bis = new BufferedInputStream(new FileInputStream("file.txt")); int b = bis.read();
5. DataInputStream
- Description: Reads Java primitive data types (int, float, double, etc.) in a machine-independent way.
- Use in Projects: Useful when working with binary data containing primitive types.
-
Example Syntax:
DataInputStream dis = new DataInputStream(new FileInputStream("data.bin")); int num = dis.readInt();
6. LineNumberInputStream
- Description: Deprecated because its functionality is replaced by LineNumberReader.
- Use in Projects: Should not be used in modern code.
7. PushbackInputStream
- Description: Allows a byte to be pushed back into the stream, so it can be read again.
- Use in Projects: Useful in parsers or compilers.
-
Example Syntax:
PushbackInputStream pbis = new PushbackInputStream(new FileInputStream("file.txt")); int b = pbis.read(); pbis.unread(b);
8. ObjectInputStream
- Description: Reads Java objects that were written using ObjectOutputStream.
- Use in Projects: Used for deserialization.
-
Example Syntax:
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("object.ser")); MyClass obj = (MyClass) ois.readObject();
9. PipedInputStream
- Description: Reads data written to a connected PipedOutputStream.
- Use in Projects: Useful for communication between threads.
-
Example Syntax:
PipedInputStream pis = new PipedInputStream(); PipedOutputStream pos = new PipedOutputStream(pis); pos.write(65); int b = pis.read(); // reads 'A'
10. SequenceInputStream
- Description: Reads data sequentially from multiple input streams as if they were a single stream.
- Use in Projects: Useful for merging multiple files into one.
-
Example Syntax:
SequenceInputStream sis = new SequenceInputStream( new FileInputStream("a.txt"), new FileInputStream("b.txt") );
11. StringBufferInputStream
- Description: Deprecated because it does not properly convert characters to bytes. Use StringReader instead.
- Use in Projects: Should not be used in modern code.
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