3. Input/Output Streams

3. Input/Output Streams
	Chapter 5. Essencial Classes

3.1. Definition

A stream is a flowing sequence of characters.

A program can get input by reading characters from a stream attached to a source.

Figure 5.5. A stream of data entering a program.

A program can produce output by writing characters to a stream attached to a destination.
Input and output sources can be anything that can contain data: a file, a string, or memory.

Figure 5.6. A stream of data leaving a program.

3.2. The System class Streams

standard input: InputStream System.in
standard output: PrintStream System.out
standard error: PrintStream System.err

3.3. InputStream Class

Figure 5.7. InputStream Class

3.4. OutputStream Class

Figure 5.8. OutputStream Class

3.5. Simple Input and Output Streams

3.5.1. FileInputStream and FileOutputStream

Read data from or write data to a file on the native file system.

3.5.2. PipedInputStream and PipedOutputStream

Implement the input and output components of a pipe.

3.5.3. ByteArrayInputStream and ByteArrayOutputStream

Read data from or write data to a byte array in memory.

3.5.4. SequenceInputStream

Concatenate multiple input streams into one input stream.

3.5.5. StringBufferInputStream

Allow programs to read from a StringBuffer as if it were an input stream.

3.5.6. Filtered Streams

To use a filtered input (output) stream, you attach the filtered stream to another input (output) stream:

DataInputStream dis = new DataInputStream(System.in.read());
String input;
while ((input = dis.readLine()) != null) {
  . . . // do something interesting here }

DataInputStream and DataOutputStream

BufferedInputStream and BufferedOutputStream

LineNumberInputStream

PushbackInputStream

Byte pushback buffer

PrintStream

3.6. Using Input and Output Streams

File inputFile = new File("farrago.txt");
File outputFile = new File("outagain.txt");

FileInputStream fis = new FileInputStream(inputFile);
FileOutputStream fos = new FileOutputStream(outputFile);

while ((c = fis.read()) != -1) {
   fos.write(c);
}
fis.close();
fos.close();

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