BufferedWriter out = null;try {  out = new BufferedWriter(new FileWriter(”filename”, true));   out.write(”aString”);} catch (IOException e) {  // error processing code} finally {  if (out != null) {    out.close();  }}

public class OracleJdbcTest{  String driverClass = "oracle.jdbc.driver.OracleDriver";     Connection con;     public void init(FileInputStream fs) throws ClassNotFoundException, SQLException, FileNotFoundException, IOException   {    Properties props = new Properties();    props.load(fs);    String url = props.getProperty("db.url");    String userName = props.getProperty("db.user");    String password = props.getProperty("db.password");    Class.forName(driverClass);       con=DriverManager.getConnection(url, userName, password);  }     public void fetch() throws SQLException, IOException  {    PreparedStatement ps = con.prepareStatement("select SYSDATE from dual");    ResultSet rs = ps.executeQuery();       while (rs.next())    {      // do the thing you do    }    rs.close();    ps.close();  }     public static void main(String[] args)  {    OracleJdbcTest test = new OracleJdbcTest();    test.init();    test.fetch();  }}

java.util.Date utilDate = new java.util.Date();java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());

public static void fileCopy( File in, File out )      throws IOException  {    FileChannel inChannel = new FileInputStream( in ).getChannel();    FileChannel outChannel = new FileOutputStream( out ).getChannel();    try    {//     inChannel.transferTo(0, inChannel.size(), outChannel);   // original -- apparently has trouble copying large files on Windows          // magic number for Windows, 64Mb - 32Kb)      int maxCount = (64 * 1024 * 1024) - (32 * 1024);      long size = inChannel.size();      long position = 0;      while ( position < size )      {        position += inChannel.transferTo( position, maxCount, outChannel );      }    }    finally    {      if ( inChannel != null )      {        inChannel.close();      }      if ( outChannel != null )      {        outChannel.close();      }    }  }

private void createThumbnail(String filename, int thumbWidth, int thumbHeight, int quality, String outFilename)    throws InterruptedException, FileNotFoundException, IOException  {    // load image from filename    Image image = Toolkit.getDefaultToolkit().getImage(filename);    MediaTracker mediaTracker = new MediaTracker(new Container());    mediaTracker.addImage(image, 0);    mediaTracker.waitForID(0);    // use this to test for errors at this point: System.out.println(mediaTracker.isErrorAny());       // determine thumbnail size from WIDTH and HEIGHT    double thumbRatio = (double)thumbWidth / (double)thumbHeight;    int imageWidth = image.getWidth(null);    int imageHeight = image.getHeight(null);    double imageRatio = (double)imageWidth / (double)imageHeight;    if (thumbRatio < imageRatio) {      thumbHeight = (int)(thumbWidth / imageRatio);    } else {      thumbWidth = (int)(thumbHeight * imageRatio);    }       // draw original image to thumbnail image object and    // scale it to the new size on-the-fly    BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);    Graphics2D graphics2D = thumbImage.createGraphics();    graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);     graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);       // save thumbnail image to outFilename    BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outFilename));    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);    JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(thumbImage);    quality = Math.max(0, Math.min(quality, 100));    param.setQuality((float)quality / 100.0f, false);    encoder.setJPEGEncodeParam(param);    encoder.encode(thumbImage);    out.close();  }

import org.json.JSONObject;......JSONObject json = new JSONObject(); json.put("city", "Mumbai");json.put("country", "India");...String output = json.toString();...

import java.io.File;import java.io.FileOutputStream;import java.io.OutputStream;import java.util.Date;   import com.lowagie.text.Document;import com.lowagie.text.Paragraph;import com.lowagie.text.pdf.PdfWriter;   public class GeneratePDF {     public static void main(String[] args) {    try {      OutputStream file = new FileOutputStream(new File("C:\\Test.pdf"));          Document document = new Document();      PdfWriter.getInstance(document, file);      document.open();      document.add(new Paragraph("Hello Kiran"));      document.add(new Paragraph(new Date().toString()));         document.close();      file.close();       } catch (Exception e) {         e.printStackTrace();    }  }}

System.getProperties().put("http.proxyHost", "someProxyURL");System.getProperties().put("http.proxyPort", "someProxyPort");System.getProperties().put("http.proxyUser", "someUserName");System.getProperties().put("http.proxyPassword", "somePassword");

public class SimpleSingleton {  private static SimpleSingleton singleInstance = new SimpleSingleton();      //Marking default constructor private  //to avoid direct instantiation.  private SimpleSingleton() {  }     //Get instance for class SimpleSingleton  public static SimpleSingleton getInstance() {       return singleInstance;  }}

import java.awt.Dimension;import java.awt.Rectangle;import java.awt.Robot;import java.awt.Toolkit;import java.awt.image.BufferedImage;import javax.imageio.ImageIO;import java.io.File;   ...   public void captureScreen(String fileName) throws Exception {     Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();   Rectangle screenRectangle = new Rectangle(screenSize);  Robot robot = new Robot();  BufferedImage image = robot.createScreenCapture(screenRectangle);  ImageIO.write(image, "png", new File(fileName));   }...

File dir = new File("directoryName"); String[] children = dir.list(); if (children == null) {   // Either dir does not exist or is not a directory } else {   for (int i=0; i < children.length; i++) {     // Get filename of file or directory     String filename = children[i];   } }    // It is also possible to filter the list of returned files. // This example does not return any files that start with `.‘.  FilenameFilter filter = new FilenameFilter() {   public boolean accept(File dir, String name) {     return !name.startsWith(".");   } }; children = dir.list(filter);    // The list of files can also be retrieved as File objects File[] files = dir.listFiles();    // This filter only returns directories FileFilter fileFilter = new FileFilter() {   public boolean accept(File file) {     return file.isDirectory();   } }; files = dir.listFiles(fileFilter);

<?xml version="1.0"?><students>  <student>    <name>John</name>    <grade>B</grade>    <age>12</age>  </student>  <student>    <name>Mary</name>    <grade>A</grade>    <age>11</age>  </student>  <student>    <name>Simon</name>    <grade>A</grade>    <age>18</age>  </student></students>

<span style="font-family:Arial;font-size:14px;">package net.viralpatel.java.xmlparser;    import java.io.File;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;   import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.Node;import org.w3c.dom.NodeList;   public class XMLParser {     public void getAllUserNames(String fileName) {    try {      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();      DocumentBuilder db = dbf.newDocumentBuilder();      File file = new File(fileName);      if (file.exists()) {        Document doc = db.parse(file);        Element docEle = doc.getDocumentElement();           // Print root element of the document        System.out.println("Root element of the document: "            + docEle.getNodeName());           NodeList studentList = docEle.getElementsByTagName("student");           // Print total student elements in document        System.out            .println("Total students: " + studentList.getLength());           if (studentList != null && studentList.getLength() > 0) {          for (int i = 0; i < studentList.getLength(); i++) {               Node node = studentList.item(i);               if (node.getNodeType() == Node.ELEMENT_NODE) {                 System.out                  .println("=====================");                 Element e = (Element) node;              NodeList nodeList = e.getElementsByTagName("name");              System.out.println("Name: "                  + nodeList.item(0).getChildNodes().item(0)                      .getNodeValue());                 nodeList = e.getElementsByTagName("grade");              System.out.println("Grade: "                  + nodeList.item(0).getChildNodes().item(0)                      .getNodeValue());                 nodeList = e.getElementsByTagName("age");              System.out.println("Age: "                  + nodeList.item(0).getChildNodes().item(0)                      .getNodeValue());            }          }        } else {          System.exit(1);        }      }    } catch (Exception e) {      System.out.println(e);    }  }  public static void main(String[] args) {       XMLParser parser = new XMLParser();    parser.getAllUserNames("c:\\test.xml");  }}

import java.util.Map;import org.apache.commons.lang.ArrayUtils;   public class Main {    public static void main(String[] args) {  String[][] countries = { { "United States", "New York" }, { "United Kingdom", "London" },     { "Netherland", "Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" } };     Map countryCapitals = ArrayUtils.toMap(countries);     System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));  System.out.println("Capital of France is " + countryCapitals.get("France")); }}

import javax.mail.*;import javax.mail.internet.*;import java.util.*;   public void postMail( String recipients[ ], String subject, String message , String from) throws MessagingException {  boolean debug = false;      //Set the host smtp address   Properties props = new Properties();   props.put("mail.smtp.host", "smtp.example.com");     // create some properties and get the default Session  Session session = Session.getDefaultInstance(props, null);  session.setDebug(debug);     // create a message  Message msg = new MimeMessage(session);     // set the from and to address  InternetAddress addressFrom = new InternetAddress(from);  msg.setFrom(addressFrom);     InternetAddress[] addressTo = new InternetAddress[recipients.length];  for (int i = 0; i < recipients.length; i++)  {    addressTo[i] = new InternetAddress(recipients[i]);  }  msg.setRecipients(Message.RecipientType.TO, addressTo);     // Optional : You can also set your custom headers in the Email if you Want  msg.addHeader("MyHeaderName", "myHeaderValue");     // Setting the Subject and Content Type  msg.setSubject(subject);  msg.setContent(message, "text/plain");  Transport.send(msg);}

import java.io.BufferedReader;import java.io.InputStreamReader;import java.net.URL;   public class Main {  public static void main(String[] args) {    try {      URL my_url = new URL("http://coolshell.cn/");      BufferedReader br = new BufferedReader(new InputStreamReader(my_url.openStream()));       String strTemp = "";      while(null != (strTemp = br.readLine())){      System.out.println(strTemp);    }    } catch (Exception ex) {      ex.printStackTrace();    }  }}