File Management

Android Club 2015

Agenda

• Working with files• Networking• XML• JSON

Copy file 1: File

• File file1 = new File("melon.txt");• File file2 = new File("apple.txt");

Copy file: stream

FileInputStream in = new FileInputStream(file1);FileOutputStream out = new FileOutputStream(file2);

Copy file: example

byte[] buffer = new byte[1024];int len;

while ((len = in.read(buffer))>0) {out.write(buffer, 0, len);

}

Practice: step 1/4

• Import JPEG file into project• Create reference to this JPEG file• Create reference to the file which will

be created

Practice: step 2/4

• Create input stream• Create output stream

Practice: step 3/4

• Create empty byte array: buffer• Size: 2048• Create int variable: lengthwhile ((length = in.read(buffer))>0) {

out.write(buffer, 0, length);

}

Practice: step 4/4

• Print “File was copied”• Surround our code with try-catch

block• Run

How to get file from computer?

File file = new File(System.getProperty("user.home") + \\Desktop\\+”favorite.mp3”)

Example

String path = System.getProperty("user.home") + "\\Desktop\\";

File file1 = new File(path + "1.mp3");File file2 = new File(path + "2.mp3");

Let’s practice

• Put big (1GB+) file to your desktop• Copy that file

Easy way

• Files.copy(source.toPath(), dest.toPath());

Easy way: practice

• Copy your file with Files class

Networking: step 1

• URL url = new URL("http://www.w3schools.com/xml/simple.xml");

Networking: step 2

InputStream in = url.openStream();

BufferedInputStream buf = new BufferedInputStream(in);

Networking: step 3

StringBuilder sb = new StringBuilder();while (true) {I nt data = in.read();

if (data == -1) {break;} else {sb.append((char) data);}

}System.out.println(sb);

Networking: practice

http://www.cbu.uz/section/rates/widget/xml1) Create URL instance with this url2) Create input stream and convert it to

BufferedInputStream3) Read stream to StringBuilder4) Print

XML parsing

• XML – extensive markup language

XML: example

<?xml version="1.0" encoding="UTF-8" ?><countries> <country> <name>Uzbekistan</name> <capital>Tashkent</capital> <currency>Sum</ currency>Sum > </country></countries>

XML: practice

• Add following countries:• Russia – Moscow – Ruble• China – Beijing – Yuan• Japan – Tokyo – Yen• US – Washington – US Dollar• Germany – Berlin - Euro

DOM: example

• DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

• DocumentBuilder builder = factory.newDocumentBuilder();

• Document doc = builder.parse("http://www.w3schools.com/xml/simple.xml");

DOM: Example

• NodeList list = doc.getElementsByTagName("food");

• for (int i = 0; i < list.getLength(); i++) {Element element = (Element) list.item(i);String value =

element.getElementsByTagName("name").item(0).getTextContent();

System.out.println(value);• }

DOM: Practice

• Get all countries list• Print all countries name• http://joerichard.net/api/ac/

countries.xml

Questions?

• Any questions

Next lesson

• Game: Tic Tac Toe

Thank you

• Thank you very much for your attention!