Exam 13: File Input and Output

You can use Java's ____ class to create objects that contain information about files or directories, such as their locations, sizes, creation dates, and whether they even exist.

while(nextLine = reader.readLine() != null)     System.out.println(nextLine); The above loop could be used to read multiple lines from a file. Explain how this loop will execute.

Briefly describe the Path class in Java.

Explain the difference between an absolute path and a relative path. Provide an example of an absolute path to a file on a system, and then provide an example of a relative path.

import java.nio.file.*; import java.nio.file.attribute.*; import java.io.IOException; public class PathDemo5 {   public static void main(String[] args)   {       Path myPath = Paths.get("C:\\Java\\Input.Output\\MyData.txt");       try       {          ---------Code here ----------          System.out.println("Creation time " + attr.creationTime());          System.out.println("Last modified time " + attr.lastModifiedTime());          System.out.println("Size " + attr.size());       }       catch(IOException e)       {          System.out.println("IO Exception");       }   } } Using the above code, create a statement on the indicated line that uses the readAttributes() method of the Files class that takes two arguments-the Path object created in the code and a BasicFileAttributes.class -and returns an instance of the BasicFileAttributes class named attr .

Some text files are ____ files that contain facts and figures, such as a payroll file that contains employee numbers, names, and salaries.

The benefit of using a(n) ____ file is the ability to retrieve a specific record from a file directly, without reading through other records to locate the desired one.

____ is an abstract class that contains methods for performing output.

Because the backslash character starts the escape sequence in Java, you must use two ____ in a string that describes a Path in the DOS operating system.

What tasks are typically performed when working with stored files in an application?

import java.nio.file.*; import java.io.*; public class ReadFile {     public static void main(String[] args)    {        Path file = Paths.get("C:\\Java\\Input.Output\\Grades.txt");        InputStream input = null;        try       {           ----Code here-------           ----Code here-------            String grade = null;            grade = reader.readLine();            System.out.println(grade);            input.close();        }        catch (IOException e)       {           System.out.println(e);        }    } } In the code above, a ReadFile class reads from the Grades.txt file. A path is declared, and an InputStream is declared using the Path . In the first indicated line, create the statement to assign a stream to the InputStream reference. In the second indicated line, declare a BufferedReader that reads a line of text from a character-input stream that buffers characters for more efficient reading.

You can store data in variables within a program, but this type of storage is temporary.

import java.nio.file.*; import java.io.*; public class ReadEmployeeFile {    public static void main(String[] args)    {       Path file =         Paths.get("C:\\Java\\Chapter.13\\Employees.txt");       String s = "";       try       {          InputStream input = new            BufferedInputStream(Files.newInputStream(file));          BufferedReader reader = new            BufferedReader(new InputStreamReader(input));          -----Code here-----          while(s != null)          {              System.out.println(s);              -----Code here-----          }          reader.close();      }      catch(Exception e)      {         System.out.println("Message: " + e);      }    } } The above code represents a program that reads an Employees text file. An InputStream is declared for the file, and a BufferedReader is created using the InputStream . On the indicated lines, write a statement that will read the first line into the String . Likewise, in the while statement, write the statement to display the String and read a new line as long as the readLine() method does not return a null value.

import java.nio.file.*; import java.io.*; public class ReadEmployeeFile2 {    public static void main(String[] args)    {       Path file =         Paths.get("C:\\Java\\Chapter.13\\Employees.txt");      String[] array = new String[3];      String s = "";      String delimiter = ",";      int id;      String name;      double payRate;      double gross;      final double HRS_IN_WEEK = 40;      double total = 0;      try      {         InputStream input = new             BufferedInputStream(Files.newInputStream(file));         BufferedReader reader = new            BufferedReader(new InputStreamReader(input));         System.out.println();         s = reader.readLine();         while(s != null)         {            -----Code here-----            id = Integer.parseInt(array[0]);            name = array[1];            payRate = Double.parseDouble(array[2]);            gross = payRate * HRS_IN_WEEK;            System.out.println("ID#" + id + " " + name +              " $" + payRate + " $" + gross);            total += gross;            s = reader.readLine();        }        reader.close();    }    catch(Exception e)    {        System.out.println("Message: " + e);     }    System.out.println(" Total gross payroll is $" + total);    } } The above code demonstrates a retrieved file where Strings are split into usable fields. On the indicated line, write a String class split() method to split the String s that accepts an argument that identifies the field delimiter (in this example, a comma) and returns an array of Strings . The result should be assigned to the String[] array .

The BufferedWriter class contains a ____ method that uses the current platform's line separator.