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Java Input / Output
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a modular approach to input/output:
- different stream objects are
connected/wrapped to handle I/O
a data stream object: a flow of data
an input stream: an object used for
reading data
an output stream: an object used for
writing data
Example: ConsoleApp.java
Java Input / Output
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two class hierarchies…
byte stream objects (8 bit bytes)
• Java abstract classes:
InputStream, OutputStream
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character/textual stream objects
16 bit UTF-16 characters
• Java abstract classes:
Reader, Writer
Week 11: Java Input / Output
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three predefined byte streams
- System.in ( InputStream object )
- System.out ( PrintStream object )
- System.err ( PrintStream object )
PrintStream: an OutputStream object that
contains print() and println()
The API for Java Input/Output
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functional categories of I/O classes
data sink streams: objects that read
from and write to data “sinks” (i.e.
sources and destinations)
processing streams: objects that
process the data (e.g. data
conversion, buffering)
processing streams offer efficient
reading, writing and functionality
The API for Java Input/Output
InputStream
data
sink
streams FileInputStream
OutputStream
Reader
Writer
FileOutputStream
FileReader
FileWriter
processing
streams
BufferedInputStream BufferedOutputStream
ObjectInputStream ObjectOutputStream
InputStreamReader ———————
BufferedReader
OutputStreamWriter ——-——
BufferedWriter
Examples of Java I/O
Applications
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keyboard input: ConsoleApp.java
- use of a byte stream and character streams
file I/O
- byte streams: FileStreams.java
- character streams: FileReaderWriter.java
- formatted data and byte stream:
DataIOTest.java
Java I/O Applications
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use of Properties file
• externalize connection parameters
• DBConnectionFile.java
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use of text file to store SQL
• CreateDBFile.java