JAVA: File Handling

File handling is an important part of any application.
Java has several methods for creating, reading, updating, and deleting files.

File Handling

The File class from the java.io package.
To use the File class, create an object of the class, and specify the filename or directory name:

import java.io.File; // Import the File class
File myObj = new File(“filename.txt”); // Specify the filename

Operations

· canRead
· canWrite
· createNewFile
· delete
· exists
· getName
· getAbsolutePath
· length
· list
· mkdir

Example

package ninteen;
import java.util.*;
import java.io.*;
public class assesment02
{
public static void main(String args[])throws Exception
{

String data1 = “HAPPY NEW YEAR”;
try {
FileOutputStream file = new FileOutputStream(“data.txt”);
byte b[] = data1.getBytes();
file.write(b);
file.close();
System.out.println(“File created successfully”);
}

catch (FileNotFoundException e)
{
e.printStackTrace();
}

catch (IOException e)
{
System.out.println(e);
}

HashMap<Character,Integer> map=new HashMap<Character,Integer>();
map.put(‘A’,0);
map.put(‘E’,0);
map.put(‘I’,0);
map.put(‘O’,0);
map.put(‘U’,0);

try {
FileInputStream file = new FileInputStream(“data.txt”);
String data = “”;
int i = 0;

while ((i = file.read()) != -1)
{
if ((char) i == ‘A’){
map.put(‘A’,map.get(‘A’)+1) ;
}

if ((char) i == ‘E’){
map.put(‘E’,map.get(‘E’)+1) ;
}

if ((char) i == ‘I’){
map.put(‘I’,map.get(‘I’)+1) ;
}

if ((char) i == ‘O’){
map.put(‘O’,map.get(‘O’)+1) ;
}

if ((char) i == ‘U’){
map.put(‘U’,map.get(‘U’)+1) ;
}
}

System.out.println(“Count of A is “+map.get(‘A’));
System.out.println(“Count of E is “+map.get(‘E’));
System.out.println(“Count of I is “+map.get(‘I’));
System.out.println(“Count of O is “+map.get(‘O’));
System.out.println(“Count of U is “+map.get(‘U’));
}

catch(FileNotFoundException e)
{
e.printStackTrace();
}

catch (IOException e)
{
e.printStackTrace();
}

}
}