Java IO.pdf - Nguyen Dang Binh

unsigned
byte
unsigned
short
N/A readUnsignedByte() One unsigned byte
N/A readUnsignedShort()
String writeBytes(String s) N/A
String writeChars(String s) N/A
String writeUTF(String s) readUTF()
7.1.2 Constructors
Java I/O
Two bytes, big-endian,
unsigned
The low-order byte of each
character in the string from
first to last
Both bytes of each character in
the string from first to last
A signed short giving the
number of bytes in the UTF-8
encoded string, followed by
the UTF-8 encoding of the
string
The DataInputStream and DataOutputStream classes have exactly the constructors you
would expect:
public DataInputStream(InputStream in)
public DataOutputStream(OutputStream out)
These chain the data streams to the underlying streams passed as arguments. For example, to
read formatted data from a file called data.txt and write formatted data to output.dat, you
would create the two streams dis and dos:
DataInputStream dis = new DataInputStream(new FileInputStream("data.txt"));
DataOutputStream dos = new DataOutputStream(
new FileOutputStream("output.dat"));
We will now take up the data formats used by data streams and the methods used to write data
in those formats.
7.2 Reading and Writing Integers
The DataOutputStream class has methods for writing all of Java's primitive integer data
types: byte, short, int, and long. The DataInputStream class has methods to read these
types. It also has methods for reading two integer data types not directly supported by Java or
the DataOutputStream class: the unsigned byte and the unsigned int.
7.2.1 Integer Formats
While Java's platform independence guarantees that you don't have to worry about precise
data formats when working exclusively in Java, you frequently need to read data created by a
program written in another language. Similarly, it's not unusual to have to write data that will
be read by a program written in a different language. For example, most Java network clients
(like HotJava) talk primarily to servers written in other languages, and most Java network
servers (like the Java Web Server) talk primarily to clients written in other languages. You
cannot naively assume that the data format Java uses is the data format other programs will
understand; you must take care to understand and recognize the data formats being used.
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