public class ConsoleReader1 {

    public static void main(String[] args) {
        String name = "";

        System.out.println("Enter your name");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        try {
            name = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }

        System.out.println("Your name is: " + name);
    }
}

public class ConsoleReader2 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter your name: ");
        String name = scanner.nextLine();

        System.out.print("Enter your age: ");
        int age = scanner.nextInt();

        System.out.println("Your name is " + name + " and you are " + age + " year old");
    }
}

public class ConsoleReader3 {

    public static void main(String[] args) {

        Console console = System.console();
        if (console == null) {
            System.out.println("No console: non-interactive mode!");
            System.exit(0);
        }

        System.out.print("Enter your username: ");
        String username = console.readLine();

        System.out.print("Enter your password: ");
        char[] password = console.readPassword();

        String passport = console.readLine("Enter your %d (th) passport number: ", 2);

        System.out.println("Your name is " + username + " and your password is " + password);
    }
}

public class FileIO {

    public static void main(String[] args) {
        writeFile();
        readFile();
    }

    static void writeFile() {
        File file = new File("testfile.txt");
        String content = "This is the text content";

        try (FileOutputStream fop = new FileOutputStream(file)) { 				\\ using the new try-resources-close

            // if file doesn't exists, then create it
            if (!file.exists()) {
                file.createNewFile();
            }

            // get the content in bytes
            byte[] contentInBytes = content.getBytes();

            fop.write(contentInBytes);
            fop.flush();
            fop.close();

            System.out.println("Done");

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

    static void readFile() {
        File file = new File("testfile.txt");

        try (FileInputStream fis = new FileInputStream(file)) { 				\\ using the new try-resources-close

            System.out.println("Total file size to read (in bytes) : "+ fis.available());

            int content;
            while ((content = fis.read()) != -1) {
                // convert to char and display it
                System.out.print((char) content);
            }

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

import java.io.*;

public class phoneBook2 {
   private RandomAccessFile file;

   public static void main(String[] args) {

      phoneBook2 pb = new phoneBook2();
   }

   public phoneBook2() {
      createFileStructure();
      writeRecord();
      readRecord();
   }

   private void createFileStructure() {
      Record r = new Record();

      try {
         // Create the file handle and open the file (read/write mode)
         File fileName = new File("d:\\java\\data\\phoneBook2.dat");
         file = new RandomAccessFile( fileName, "rw" );

         // Create 100 blank records in the file
         for ( int i = 0; i < 100; i++)
         r.write( file );

         System.out.println("Written 100 Blank records\n");

      } catch ( IOException ioex ){
         System.out.println("File does not exists");
      }
   }

   private void writeRecord() {
      int recordNumber = 37; // using a fixed record number
      Record r = new Record();

      try {
         // Create the file handle and open the file (read/write mode)
         File fileName = new File("d:\\java\\data\\phoneBook2.dat");
         file = new RandomAccessFile( fileName, "rw" );

         // Write the record to the file
         if ( recordNumber > 0 && recordNumber < 100 ) {
            r.setName("Paul Valle");
            r.setPhone("0207-876-8765");

            // Go to the record 37 location (bucket)
            file.seek( (recordNumber - 1) * r.size() );

            // Write the record out
            r.write( file );

            System.out.println("Updated record 37\n");
         }
      } catch ( IOException ioex ){
         System.out.println("File does not exists");
      }
   }

   private void readRecord() {
      int recordNumber = 37;
      Record r = new Record();

      try {
         // Create the file handle and open the file (read only mode)
         File fileName = new File("d:\\java\\data\\phoneBook2.dat");
         file = new RandomAccessFile( fileName, "r" );

         // Jump to the file location using seek
         file.seek( (recordNumber - 1) * r.size() );

         // Display the offset
         System.out.println("File offset position: " + file.getFilePointer() );
         System.out.println("File Length: " + file.length() );

         // Read the record
         r.read( file );

         // Display the record
         System.out.println("Record:37 - Name: " + r.getName() + " Phone: " + r.getPhone() );
      } catch ( IOException ioex ){
         System.out.println("File does not exists");
      }
   }
}

class Record {
   private String name;
   private String phone;

   // Constructor
   public Record() { this ("", ""); }

   // Overloaded Constructor
   public Record(String n, String p) {
      name = n;
      phone = p;
   }

   // Public method to read the data from the file
   public void read( RandomAccessFile file ) throws IOException {
      setName( padData( file ) );
      setPhone ( padData( file ) );
   }

   // Public method to write the data to the file
   public void write( RandomAccessFile file ) throws IOException {
      writeData( file, getName() );
      writeData( file, getPhone() );
   }

   // The method that actually writes the data to the file
   private void writeData( RandomAccessFile f, String n) throws IOException {
      StringBuffer buf = null;

      if ( n != null )
         buf = new StringBuffer( n );
      else
         buf = new StringBuffer( 20 );
         buf.setLength( 20 );
         f.writeChars( buf.toString() );
   }

   // This pads the data so to make the data all the same size
   // we will go for a size of 20
   private String padData( RandomAccessFile f ) throws IOException {
      char data[] = new char[ 20 ], temp;

      for ( int i = 0; i < data.length; i++ ) {
         temp = f.readChar();
         data[ i ] = temp;
      }

      return new String ( data ).replace( '\0', ' ' );
   }

   // This method hard codes the value for the size of the record
   // which is 20
   public static int size() { return 20; }

   // The get and set methods
   public void setName(String n) { name = n; }

   public void setPhone(String p) { phone = p; }

   public String getName() { return name; }

   public String getPhone() { return phone; }
}

      try {
         // Create a new file and rename
         test1.createNewFile();
         test1.renameTo(test2);

         // set test2 file as Read-Only
         test2.setReadOnly();

         // Create some directories then delete one
         dir1.mkdirs();             // used for creating multiple directories
         dir2.mkdir();
         dir3.mkdir();
         dir3.delete();

         // First let check that it exists
         if ( f.exists()) {
           // Let's test the object to see if its a file or directory
           if ( f.isFile() )
           {
              System.out.println("This file exists: " + f.getName());
              System.out.println("The absolute path of the file is: " + f.getAbsolutePath());
              System.out.println("getParent returns:" + f.getParent() + "\n");
              System.out.println("The canonical path of the file is: " + f.getCanonicalPath());

              System.out.println("Read the file:" + f.canRead());
              System.out.println("Write to the file:" + f.canWrite());

              System.out.println("File hidden:" + f.isHidden());
              long lm = f.lastModified();
              System.out.println("Last Modified:" + new Date(lm));

              System.out.println("Size of file: " + f.length()/1024 + "KB" );
           }
           else if (f.isDirectory()) {
                 System.out.println("This directory exists: " + f.getName());
                 System.out.println("The absolute path of the file is: " + f.getAbsolutePath());
           }
        } else {
             System.out.println("The file or directory does not exists: " + f.getName());
        }
      } catch (IOException e) {
           System.out.println("IOException caught" + e);
      }
   }
}