![Example 1 - Reading from console
import java.io.*;
public class ExReading
{
public static void main(String[] args) throws IOException
{
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(isr);
String name = "";
System.out.print("Please enter your name: ");
name = in.readLine();
System.out.println("Hello, " + name + "!");](https://image.slidesharecdn.com/fileinputandoutput-230211161705-026ba9b3/85/File-Input-and-output-pptx-24-320.jpg)
![Example 2 - Reading from a file
import java.io.*;
class ExReading
{
public static void main(String[] args) throws IOException
{
Reader in = new FileReader(“c/abc.txt”);
try
{
char c = (char)input.read();
System.out.println("Data read from a file - '" + c + "'");
}
catch(Exception e) {
System.out.println(e);
}
finally {
input.close();](https://image.slidesharecdn.com/fileinputandoutput-230211161705-026ba9b3/85/File-Input-and-output-pptx-25-320.jpg)
![Writing data using FileWriter
import java.io.*;
public class ExWriting
{
public static void main(String[] args) throws IOException
{ Writer out = new FileWriter("C:Desktopcse.txt");
msg = "cse";
try
{
out.write(msg);
System.out.println("Writing done!!!");
}
catch(Exception e)
{ System.out.println(e); }
finally
{ out.close(); }
}} }](https://image.slidesharecdn.com/fileinputandoutput-230211161705-026ba9b3/85/File-Input-and-output-pptx-26-320.jpg)
![File
import java.io.File;
class FileDemo {
static void p(String s) {
System.out.println(s);
}
public static void main(String args[]) {
File f1 = new File("/java/COPYRIGHT");
p("File Name: " + f1.getName());
p("Path: " + f1.getPath());
p("Abs Path: " + f1.getAbsolutePath());
p("Parent: " + f1.getParent());
p(f1.exists() ? "exists" : "does not exist");
p(f1.canWrite() ? "is writeable" : "is not writeable");
p(f1.canRead() ? "is readable" : "is not readable");
p("is " + (f1.isDirectory() ? "" : "not" + " a directory"));
p(f1.isFile() ? "is normal file" : "might be a named pipe");
p(f1.isAbsolute() ? "is absolute" : "is not absolute");
p("File last modified: " + f1.lastModified());
p("File size: " + f1.length() + " Bytes");
}
}](https://image.slidesharecdn.com/fileinputandoutput-230211161705-026ba9b3/85/File-Input-and-output-pptx-33-320.jpg)
![Creating File using File class
import java.io.*;
class ExFile
{
public static void main(String[] args)
{
try {
File file = new File(“c/abc.txt");
if (file.createNewFile())
{
System.out.println("New File is created!");
} else
{
System.out.println("File already exists.");
}
} catch (IOException e)
{
e.printStackTrace();
}
}](https://image.slidesharecdn.com/fileinputandoutput-230211161705-026ba9b3/85/File-Input-and-output-pptx-35-320.jpg)
![List out all files in a directory or path
import java.io.*;
class ExFileList
{
public static void main(String[] args)
{
File f=new File(“c:/abc/cse");
String filenames[]=f.list();
for(String filename:filenames)
{
System.out.println(filename);
}
}
}](https://image.slidesharecdn.com/fileinputandoutput-230211161705-026ba9b3/85/File-Input-and-output-pptx-36-320.jpg)
File Input and output.pptx
- 1. File I/O
- 2. File Input and Output Operations:- File I/O operations are performed using the concept of streams. A stream means a continuous flow of data. A stream is a logical container of data that allows us to read from and write to it. The stream-based IO operations are faster than normal IO operations
- 3. Functionality of java streams
- 4. Every Java program creates 3 streams automatically. These streams are attached to the console 1. System.out: standard output stream for console output operations. 2. System.in: standard input stream for console input operations. 3. System.err: standard error stream for console error output operations.
- 5. Example For Streams 1. System.out.println(“hai"); 2. System.err.println(“welcome"); int a=System.in.read(); //returns ASCII code of 1st character System.out.println((char)a); //will print the charact
- 6. Java provides two types of streams • 1.Byte Stream • 2. Character Stream
- 7. Stream with various built-in classes used by the java IO system
- 8. Java Byte Stream The java byte stream is defined by two abstract classes 1. InputStream 2. OutputStream. The InputStream class used for byte stream based input operations, The OutputStream class used for byte stream based output operations. The InputStream and OutputStream classes have several classes to perform various IO operations based on the byte stream.
- 10. InputStream class The InputStream class has defined as an abstract class it has the following methods which have implemented by its concrete classes.
- 11. OutputStream class The OutputStream class has defined as an abstract class, It has the following methods which have implemented by its concrete classes.
- 12. i) Reading data using BufferedInputStream BufferedInputStream class to read data from the console. BufferedInputStream(InputStream inputstream) BufferedInputStream(InputStream inputstream, int bufSize) The BufferedInputStream class use a method read( ) to read a value from the console, or file
- 13. Ex 1: Reading from console
- 14. EX2: Reading from a file
- 15. Writing data using BufferedOutputStream
- 16. Character Stream in java IO stream manages 16-bit Unicode characters, it is called a character stream. The Unicode set is basically a type of character set where each character corresponds to a specific numeric value within the given character set. character stream is defined by two abstract classes, Reader and Writer
- 17. Reader class used for character stream based input operations Writer class used for character stream based output operations Reader and Writer classes have several concreate classes to perform various IO operations based on the character stream.
- 19. Reader class The Reader class has defined as an abstract class the following methods implemented by its concrete classes
- 21. Writer class The Writer class has defined as an abstract class. It has the following methods implemented by its concrete classes.
- 23. Reading data using BufferedReader BufferedReader class to read data from the console. The BufferedInputStream class needs InputStreamReaderclass. The BufferedReader use a method read( ) to read a value from the console, or file, or socket.
- 24. Example 1 - Reading from console import java.io.*; public class ExReading { public static void main(String[] args) throws IOException { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader in = new BufferedReader(isr); String name = ""; System.out.print("Please enter your name: "); name = in.readLine(); System.out.println("Hello, " + name + "!");
- 25. Example 2 - Reading from a file import java.io.*; class ExReading { public static void main(String[] args) throws IOException { Reader in = new FileReader(“c/abc.txt”); try { char c = (char)input.read(); System.out.println("Data read from a file - '" + c + "'"); } catch(Exception e) { System.out.println(e); } finally { input.close();
- 26. Writing data using FileWriter import java.io.*; public class ExWriting { public static void main(String[] args) throws IOException { Writer out = new FileWriter("C:Desktopcse.txt"); msg = "cse"; try { out.write(msg); System.out.println("Writing done!!!"); } catch(Exception e) { System.out.println(e); } finally { out.close(); } }} }
- 27. Writing from a Binary File DataOutputStream and DataInputStream enable you to write or read primitive data to or from a stream. They implement the DataOutput and DataInput interfaces, DataOutputStream extends FilterOutputStream, which extends OutputStream. DataOutputStream defines the following constructor: DataOutputStream(OutputStream outputStream) DataOutput defines methods final void writeDouble(double value) throws IOException final void writeBoolean(boolean value) throws IOException final void writeInt(int value) throws IOException
- 28. Reading from a Binary File DataInputStream is the complement of DataOuputStream. It extends FilterInputStream,which extends InputStream, and it implements the DataInput interface. DataInputStream(InputStream inputStream) Methods: double readDouble( ) throws IOException boolean readBoolean( ) throws IOException int readInt( ) throws IOException
- 29. File Class File is a built-in class in Java. File class has been defined in the java.io package. The File class represents a reference to a file or directory. File class has various methods to perform operations like creating a file or directory, reading from a file, updating file content, and deleting a file or directory.
- 31. File class Methods 1. boolean canExecute() : Tests whether the application can execute the file denoted by this abstract pathname. 2. boolean canRead() : Tests whether the application can read the file denoted by this abstract pathname. 3. boolean canWrite() : Tests whether the application can modify the file denoted by this abstract pathname. 4. int compareTo(File pathname) : Compares two abstract pathnames lexicographically. 5. boolean createNewFile() : Atomically creates a new, empty file named by this abstract pathname . 6. static File createTempFile(String prefix, String suffix) : Creates an empty file in the default temporary-file directory.
- 32. 8) boolean exists() : Tests whether the file or directory denoted by this abstract pathname exists. 9) String getAbsolutePath() : Returns the absolute pathname string of this abstract pathname. 10) long getFreeSpace() : Returns the number of unallocated bytes in the partition . 11) String getName() : Returns the name of the file or directory denoted by this abstract pathname. 12) String getParent() : Returns the pathname string of this abstract pathname’s parent. 13) File getParentFile() : Returns the abstract pathname of this abstract pathname’s parent. 14) String getPath() : Converts this abstract pathname into a pathname string. 15) boolean isDirectory() : Tests whether the file denoted by this pathname is a directory.
- 33. File import java.io.File; class FileDemo { static void p(String s) { System.out.println(s); } public static void main(String args[]) { File f1 = new File("/java/COPYRIGHT"); p("File Name: " + f1.getName()); p("Path: " + f1.getPath()); p("Abs Path: " + f1.getAbsolutePath()); p("Parent: " + f1.getParent()); p(f1.exists() ? "exists" : "does not exist"); p(f1.canWrite() ? "is writeable" : "is not writeable"); p(f1.canRead() ? "is readable" : "is not readable"); p("is " + (f1.isDirectory() ? "" : "not" + " a directory")); p(f1.isFile() ? "is normal file" : "might be a named pipe"); p(f1.isAbsolute() ? "is absolute" : "is not absolute"); p("File last modified: " + f1.lastModified()); p("File size: " + f1.length() + " Bytes"); } }
- 34. File Output File Name: COPYRIGHT Path: /java/COPYRIGHT Abs Path: /java/COPYRIGHT Parent: /java exists is writeable is readable is not a directory is normal file is absolute File last modified: 812465204000 File size: 695 Bytes
- 35. Creating File using File class import java.io.*; class ExFile { public static void main(String[] args) { try { File file = new File(“c/abc.txt"); if (file.createNewFile()) { System.out.println("New File is created!"); } else { System.out.println("File already exists."); } } catch (IOException e) { e.printStackTrace(); } }
- 36. List out all files in a directory or path import java.io.*; class ExFileList { public static void main(String[] args) { File f=new File(“c:/abc/cse"); String filenames[]=f.list(); for(String filename:filenames) { System.out.println(filename); } } }