How to generate a random alphanumeric word with special characters of variable length

Usually we need to create a random word of some 8+ character to use as a password or an encryption key.

I have recently created this one, though very simple but very effective.

I have tried to replicate the same sequence and run in a loop of 1000000 iteration but with length of 8 characters there were no repetition. Hope the readers would like it.

package in.codeZila.www.utility;

public class RandomWordGenerator {

 public static final String getRandomWord(int length) {
  String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890!@#$%^&*";
  String rw = "";
  for(int i = 0; i < length; i++) {
   int index = (int) Math.floor(Math.random() * 62);
   rw += chars.charAt(index);
  }

  return rw;
 }
 
 public static void main(String[] args) {
  for(int i=0;i<100;i++){
   String randomPwd=getRandomWord(8);
   System.out.println(randomPwd);
  }
 }
 
}

The Random words generated are :

Please feel free to ask any doubts or clarifications.

How to get the XML String for a DTO (Data transfer object) using XStream

To get the XML for a DTO XStream (com.thoughtworks.xstream.XStream) is used, Download the "xstream-1.4.2.jar" jar : Click Here and add into your lib folder.

The Method which returns the XML for the passed DTO:

public static String getDTOasXML(Object dto){
 XStream xstream = new XStream();
        return xstream.toXML(dto);
}

The UserDto which needs to be converted to XML :

public class UserDto{

 
 private Long userId;

 private String userName;

 private String userEmail;

 public Long getUserId() {
  return userId;
 }

 public void setUserId(Long userId) {
  this.userId = userId;
 }

 public String getUserName() {
  return userName;
 }

 public void setUserName(String userName) {
  this.userName = userName;
 }

 public String getUserEmail() {
  return userEmail;
 }

 public void setUserEmail(String userEmail) {
  this.userEmail = userEmail;
 } 
}

Note: Notice that the fields are private. XStream doesn't care about the visibility of the fields. No getters or setters are needed. Also, XStream does not limit you to having a default constructor.

The Test Class to implement the XStream.toXML() method :

package in.codeZila.test;

import in.codeZila.test.dto.UserDto;
import com.thoughtworks.xstream.XStream;


public class Test{
 
 /**
  * Using XStream method toXML():String to generate the XML for the passed DTO object
  * @param dto
  * @return dto XML as String
  */
 public static String getDTOasXML(Object dto){
  XStream xstream = new XStream();
  /**
   * Now, to make the XML outputted by XStream more concise, 
   * you can create aliases for your custom class names to XML 
   * element names. This is the only type of mapping required to 
   * use XStream and even this is optional.
   * 
   * Note: This is an optional step. Without it XStream would work fine, 
   * but the XML element names would contain the fully qualified name of 
   * each class (including package) which would bulk up the XML a bit.
   */
  xstream.alias("UserDto", UserDto.class);
  return xstream.toXML(dto);
 }
 
 public static void main(String[] args) {
  /**
   * Instantiate the UserDto and set its variables
   */
  UserDto userDto=new UserDto();
  userDto.setUserId(new Long(1));
  userDto.setUserName("CodeZila");
  userDto.setUserEmail("codezila@codezila.in");
  /**
   * Pass the userDto Object created above as getDTOasXML() argument
   */
  String dtoXml=Test.getDTOasXML(userDto);
  System.out.println(dtoXml);
 }
}

The Output XML :

Thats all, how simple XStream is!

Summary:

• Create element name to class name aliases for any custom classes using xstream.alias(String elementName, Class cls); 
• Convert an object to XML using xstream.toXML(Object obj); 
• Convert XML back to an object using xstream.fromXML(String xml);

Your valuable inputs and suggestions are welcomed!

Java Method to copy a folder directory contents from source location to destination location

public void copyDirectory(java.io.File sourceLocation, java.io.File targetLocation) {
 System.out.println("Starting Copying");
 try {
  if (sourceLocation.isDirectory()) {
   if (!targetLocation.exists()) {
    targetLocation.mkdir();
   }

   String[] children = sourceLocation.list();
   for (int i = 0; i < children.length; i++) {
    copyDirectory(new java.io.File(sourceLocation, children[i]),
      new java.io.File(targetLocation, children[i]));
   }
  } 
  else {
   java.io.InputStream in = new java.io.FileInputStream(sourceLocation);
   java.io.OutputStream out = new java.io.FileOutputStream(targetLocation);
   byte[] buf = new byte[1024];
   int len;
   while ((len = in.read(buf)) > 0) {
    out.write(buf, 0, len);
   }
   in.close();
   out.close(); 
  }
 } catch (java.io.IOException e) {
  e.printStackTrace();
  throw new RuntimeException(e);
 }
 System.out.println("Completed Copying");
}

To test this method just create a directory at any location say: (c:/sourceLocation/) with some files in it. And you want to copy all the contents of this directory to a new location say : (d:/targetLocation) which may or may not exist. Then this function will create the target location and copy all the contents from the given source location to the target location. 

 The sample test class to test this method:

public class TestCopyDrectory {

 public static void main(String[] args) {
  copyDirectory(new java.io.File("C:/sourceLocation/"), new java.io.File("D:/targetLocation"));
 }

 public static void copyDirectory(java.io.File sourceLocation, java.io.File targetLocation) {
  System.out.println("Starting Copying");
  try {
   if (sourceLocation.isDirectory()) {
    if (!targetLocation.exists()) {
     targetLocation.mkdir();
    }

    String[] children = sourceLocation.list();
    for (int i = 0; i < children.length; i++) {
     copyDirectory(new java.io.File(sourceLocation, children[i]),
       new java.io.File(targetLocation, children[i]));
    }
   } 
   else {
    java.io.InputStream in = new java.io.FileInputStream(sourceLocation);
    java.io.OutputStream out = new java.io.FileOutputStream(targetLocation);
    byte[] buf = new byte[1024];
    int len;
    while ((len = in.read(buf)) > 0) {
     out.write(buf, 0, len);
    }
    in.close();
    out.close(); 
   }
  } catch (java.io.IOException e) {
   e.printStackTrace();
   throw new RuntimeException(e);
  }
  System.out.println("Completed Copying");
 }

}