I/O

Input/Output

• To perform operations on files / folders /streams java provides us many library classes.
• These classes are defined in package java.io.

Class File

• It represents file and directory on secondary storage.
• This class is used for operations on files and directories or to get information about them.

• File(String pathname)
  • Creates a new File object representing the given pathname.
  • For ex:
  1. f1=new File("c:/turboc/bin/demo.c");
  2. f2=new File("c:/turboc/bin");
• File(String parent, String child)
• Creates a new File object representing the given path of parent and child name.
• For ex:
• f3=new File("c:/turboc/bin","demo.c");
• f4=new File("c:/turboc/bin","project");F
• File(File parent, String child)
• Creates a new File object from a parent path and a child name.
• For ex:
• f5=new File(f2,"demo.c");
• f6=new File(f2,"project");

• boolean mkdir()
• Creates the directory.
• For ex:

            File tdir=new File("c:/temp/test");
            tdir.mkdir();

• long length()
• Returns the length of the file.
• For ex:

            File fa=new File("c:/temp/demo.jpg");
            long n=fa.length();

• String[ ] list()
• Returns an array of strings naming the files and directories in the directory .
• For ex:

            File fdir=new File("c:/temp");
            String arr[]=fdir.list();
            for(String nm:arr)
	            System.out.println(nm);

• boolean renameTo(File dest)
• Renames the file or directory.
• For ex:

            File fa=new File("c:/temp/demo.sql");
            File fb=new File("c:/temp/backup.sql");
            fa.renameTo(fb);

• boolean isDirectory()
• Return true if object is a directory.
• For ex:

            File fa=new File("c:/temp/project");
            boolean res=fa.isDirectory();

• boolean isFile()
• Returns true if object is a file.
• For ex:

            File fa=new File("c:/temp/project");
            boolean res=fa.isFile();

• boolean exists() 
• Tests whether the file or directory exists.
• For ex:

            File fa=new File("c:/temp/project");
            boolean res=fa.exists();

• boolean delete()
• Deletes the file or directory represented by this object.
• For ex:

            File fa=new File("c:/temp/project");
            boolean res=fa.delete();

• String getName()
• Returns the name of the file or directory.
• For ex:

            File fa=new File("c:/temp/demo.sql");
            String fname=fa.getName();

• String getPath()
• Return pathname string.
• For ex:

            File fa=new File("c:/temp/demo.sql");
            String fname=fa.getPath();

• boolean canRead()
• Tests whether the application can read the file .
• For ex:

            File fa=new File("c:/temp/demo.sql");
            boolean res=fa.canRead();

• boolean canWrite()
• Tests whether the application can modify the file.
• For ex:

            File fa=new File("c:/temp/demo.sql");
            boolean res=fa.canWrite();

 import java.util.*;
 import java.io.*;
 class demo
 {
 public static void main(String args[])
    {
        Scanner stdin=new Scanner(System.in);
        System.out.print("Enter path ");
        String path=stdin.next();
        File fx=new File(path);
        if(fx.exists())
	    {
	        if(fx.isFile())
   	        {
	            if(fx.delete())
		            System.out.println("File deleted...");
	            else
		            System.out.println("Cannot delete the file...");
	        }
	        else
	            System.out.println("Not a File");
	    }
        else
 	        System.out.println("Path Not Found");
    }
 }    
  

Enter path c:\temp\a2.txt 

File deleted...