Java Basic IO
Explain how to use basic I/O. References: Basic I/O Reading and writing files in Java (Input/Output) - Tutorial 1. I/O Streams An I/O Stream represents and input source or an output destination. A stream is a sequence of data. input stream: is used to read data from source, once item at a time. outputs stream: is used to write data to a destination, once item |at a time. --stream--> 0101010101... ----------> java.io package 1.1. Bytes Streams Bytes Streams is used to perform input and output of 8-bit bytes. All other stream types are built on byte streams. Examples: import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class CopyBytes { public static void main(String[] args) throws IOException { FileInputStream in = null; FileOutputStream out = null; try { in = new FileInputStream("xanadu.txt"); out = new FileOutputStream("outagain.txt"); int c; while ((c = in.read()) != -1) { out.write(c); } } finally { if (in != null) { in.close(); } if (out != null) { out.close(); } } } } 1.2. Character Streams Character values is stored using Unicode conventions. Character stream I/O automatically translates this internal format to and from the local character set.( E.g: Western: ASCII, Japan:Shift-JIS) Example: private boolean writeXmlFile(Map<String, String> object, IPath filePath) { try (FileOutputStream outputStream = new FileOutputStream(filePath.toFile())) { XMLStreamWriter writer = XMLOutputFactory.newFactory().createXMLStreamWriter(outputStream, StandardCharsets.UTF_8.name()); writer.writeStartDocument(StandardCharsets.UTF_8.name(), "1.0"); //$NON-NLS-1$ writer.writeStartElement("A"); writer.writeAttribute("xmlns:i", "http://www.w3.org/2001/XMLSchema-instance"); writer.writeAttribute("xmlns", "http://schemas.microsoft.com/2003/10/Serialization/Arrays"); for (Map.Entry<String, String> entry : object.entrySet()) { writer.writeStartElement("A"); writer.writeStartElement("A"); writer.writeCharacters("A"); writer.writeEndElement(); writer.writeStartElement("A"); writer.writeCharacters("A"); writer.writeEndElement(); writer.writeEndElement(); } writer.writeEndElement(); writer.writeEndDocument(); writer.flush(); return true; } catch (IOException | XMLStreamException e) { System.out("Error writing XML file", e); //$NON-NLS-1$ } return false; }