Java I/O Examples : How To Delete Temporary File

Intro

This examples will demonstrates how to delete a temporary file using Java program. To delete it, you can use one of the following method:

• deleteOnExit(), delete temporary file when program is terminated or exited.
• delete(), delete temporary file imediately,

Examples

package com.freesamplecode.java.io;

import java.io.File;
import java.io.IOException;

public class DeleteTemporaryFileDemo {
	public static void main(String[] args){
		
		try {
			
			// create temporary file "test.tmp"
			
			File tempFile = File.createTempFile("test", ".tmp");
			
			
			// delete temporary file when the program is terminated or existed
			
			tempFile.deleteOnExit();
			
			//delete temporary file immediately
			
            //tempFile.delete();
			
			System.out.println("Temporary file "+tempFile.getName() + " is successfully deleted");
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

Output

Temporary file test1195400416650249998.tmp is successfully deleted

Java I/O Examples : How To Generate A File Checksum Value With MD5 Algorithm

Intro

This examples will demonstrates how to generate a file checksum with MD5 algorithm. To generate it, you should use MessageDigest class. This output is in the hexadecimal format.

Examples

package com.freesamplecode.java.io;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class FileChecksumDemo {
	public static void main(String[] args){
		
		//Step 1 : prepare file name
		String fileName = "D:/temp/test/file_test.txt";
		
		try {
			
			//Step 2 : create MD5 MessageDigest object
			MessageDigest messageDigest = MessageDigest.getInstance("MD5");
			
			// Step 3 : read data
			FileInputStream fis = new FileInputStream(fileName);
			
			byte[] bytedata = new byte[1024];
			
			int read = 0;
			
			while((read = fis.read(bytedata)) != -1){
				messageDigest.update(bytedata, 0, read);
			}
			
			//Step 4: calculate digest bytedata 
			byte[] bytemd = messageDigest.digest();
			
			//Step 5 : convert into hex format
			
			StringBuffer sb = new StringBuffer("");
			
			for(int i = 0; i < bytemd.length; i++){
				sb.append(Integer.toString((bytemd[i] & 0xff) + 0x100, 16).substring(1));
			}
			
			//Step 6 : Display to console
			System.out.println("Result.....");
			System.out.println(fileName+" : " + sb.toString());
			
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
	}
}

Output

Result.....
D:/temp/test/file_test.txt : c16665a5040f355d62eea6d2d5274c83

Screenshot

Java Collection Examples : How To Remove Duplicate Elements From An Array

Intro

This examples will demonstrates how to remove duplicate elements from an array. To get it, you have to convert an array into a Set collection first.

Examples

package com.freesamplecode.java.array;

import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class RemoveDuplicateElementDemo {
	public static void main(String[] args){
		
		   // Step 1:  Prepare a duplicate array
		   String[] strArray = { "A", "B", "B", "C", "A", "D", "B", "A", "B", "D" };
		   
		   System.out.println("Original Array : "+Arrays.toString(strArray));
		   
		   // Step 2 : Convert an array to list
		   List list = Arrays.asList(strArray);
		   
		   // Step 3 : Create a Set object from list
		   Set set = new HashSet(list);
		   
		   // Step 4 : Create an array object to hold values from set
		   String[] newArray = new String[set.size()];
		   
		   // Step 5 : Convert a Set into an Array
		   set.toArray(newArray);
		   
		   // Step 6 : Display value after removing duplicate to console
		   System.out.print("After removing duplicates: "+Arrays.toString(newArray));
		   
		   
		   
	}
}

Output

Original Array : [A, B, B, C, A, D, B, A, B, D]
After removing duplicates: [D, A, B, C]

Screenshot

Java Date & Time Examples : How To Convert A String Into Date

Intro

This examples will demonstrates how to convert a string into date object. It is very quite simple, you can use SimpleDateFormat.parse() method to parse a string format into date object.

Examples

package com.freesamplecode.java.datetime;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class ConvertStringToDateDemo {
 public static void main(String[] args){
  String dateString1 = "8-Jan-2016";
  String dateString2 = "08/01/2016";
  String dateString3 = "Jan 8, 2016";
  
  SimpleDateFormat sdf1 = new SimpleDateFormat("dd-MMM-yyyy");
  SimpleDateFormat sdf2 = new SimpleDateFormat("dd/MM/yyyy");
  SimpleDateFormat sdf3 = new SimpleDateFormat("MMM dd, yyyy");
  
  try {
   Date date1 = sdf1.parse(dateString1);
   System.out.println(date1);
   
   Date date2 = sdf2.parse(dateString2);
   System.out.println(date2);
   
   Date date3 = sdf3.parse(dateString3);
   System.out.println(date3);
   
   
  } catch (ParseException e) {
   e.printStackTrace();
  }
  
 }
}

Output

Fri Jan 08 00:00:00 ICT 2016
Fri Jan 08 00:00:00 ICT 2016
Fri Jan 08 00:00:00 ICT 2016

Screenshot

Java Date & Time Examples : How To Convert Date To String

Intro

This examples will demonstrates how to convert a date object into string format. It is very quite simple, you can use SimpleDateFormat.format() method to format a date object into specify format.

Examples

package com.freesamplecode.java.datetime;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class ConvertDateToStringDemo {
 public static void main(String[] args){
  
  //get today
  Date today = Calendar.getInstance().getTime();
  
  //create a simple date format object to specify string format
  SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh.mm.ss");
  
  //display today in string format
  System.out.println("Today is : "+sdf.format(today));
 }
}

Output

Today is : 31/03/2016 05.58.21

Screenshot

Java I/O Examples : How To Move A File To Another Directory

Intro

This examples will demonstrates how to move a file from one directory to another directory. It's very tricky, we will use File.renameTo() method to move it.

Examples

package com.freesamplecode.java.io;

import java.io.File;

public class MoveFileDemo {
 public static void main(String[] args){
  
  String fileName = "test.txt";
  
  //source directory
  File sourceDir = new File("D:/temp/sourcedir/"+fileName);
  
  //destination directory
  File destDir = new File("D:/temp/destdir/"+fileName);
  
  if(sourceDir.renameTo(destDir)){
   System.out.println("Move File operation is successfully...");
  }else{
   System.out.println("Failed to execute move file operation, please try again...");
  }
 }
}

Output

Move File operation is successfully...

Screenshot

before move file

after move file

Java Examples : How To Get Home Directory

Intro

This examples will demonstrates how to display an user home directory. It is quite simple, we can use System.getProperty() method with "user.home" parameter.

Examples

package com.freesamplecode.java.basic;

public class GetUserHomeDirectoryDemo {
 public static void main(String[] args){
  String homeDirectory = System.getProperty("user.home");
  
  System.out.println("Home Directory : "+homeDirectory);
 }
}

Output

Home Directory : C:\Users\Dev

Screenshot