Example : Write a java program for writing/display output on console simply (or without using PrintWriter class).
class Example
{
    public static void main(String[] args)throws Exception 
	{
           char ch1,ch2;                                                                  
	   ch1 = 'J';                                                              
	   System.out.write(ch1);                                                    
	   System.out.write('\n');
	   ch2 = '5';                                                              
	   System.out.write(ch2);                                                    
	   System.out.write('\n');        
        }
}
Example : Write a java program for writing/display output on console using PrintWriter class.
import java.io.PrintWriter;
class Example
{
    public static void main(String[] args)throws Exception 
	{
           PrintWriter wt = new PrintWriter(System.out, true);                           
	   wt.println("File Handling Console Writing Program");                                         
	   wt.println(200);                                                              
           wt.println(-32.01);        
        }
}

--------  OR  --------
import java.io.PrintWriter;
class Example
{
    public static void main(String[] args) 
	{
           System.out.println("First File");

           PrintWriter wt = new PrintWriter(System.out);    
	   wt.write("File Handling Program1");   // or wt.println("File Handling Program1");          
	   wt.flush();  
	   wt.close();  
        }
}
Output :
First File
File Handling Program1
Example : Write a java program for writing text in the file at specific location using PrintWriter class.
import java.io.File;
import java.io.PrintWriter;
class Example
{
      public static void main(String[] args)throws Exception 
	{
           PrintWriter wt =null;      
           wt = new PrintWriter(new File("D:\\New folder\\test.txt"));  
           wt.write("File Handling Program2");                                                   
           wt.flush();  
           wt.close();   
        }
}
Output :
Open the test.txt file in D drive of the computer system and open it to see the output File Handling Program2.
Example : Write a java program for writing text in the file at specific location copy them into another file and then display the copied text using File concept.
import java.io.PrintWriter;
import java.io.File;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
 
class Example 
{ 
	public static void main(String[] args) 
	{ 
		try 
		{
		   //New file creation code
			
		   PrintWriter wt =null;      
		   wt = new PrintWriter(new File("D:\\New folder\\test1.txt"));  
		   wt.write("File Handling Program2");                                                   
		   wt.flush();  
		   wt.close();	
			
		   //copy text from test1.txt to another file test2.txt	
		
		   FileReader fr = new FileReader("D:\\New folder\\test1.txt");
		   BufferedReader br = new BufferedReader(fr);
		   FileWriter fw = new FileWriter("D:\\New folder\\test2.txt", true);
		   String str1,str2;			
		   while ((str1 = br.readLine()) != null)  // Read a line of text
		    { 
	             fw.write(str1); 
		     fw.flush();
		    }	
		   br.close();
		   fw.close();
		   System.out.println("File copied successfully");
			
		   //display the copied text from file test2.txt

		   BufferedReader br1 = new BufferedReader(new FileReader("D:\\New 
                       folder\\test2.txt"));            
		   System.out.println("\nThe output are =");
		   while ((str2 = br1.readLine()) != null) 
		      {
		        System.out.println(str2);
		      }			
		   br1.close();			
		}
		catch (IOException e) 
		  {			
		     e.printStackTrace();
		  }
	}
}
Example : Write a java program for reading text from the file stored at specific location and display them line by line and word by word using File handling concept.
import java.io.*;
import java.util.*;

class Example 
{
  public static void main(String[] args) throws Exception 
   {

    // Reading a text file contents line by line using Scanner class
	
    System.out.println("Reading a text file contents line by line: ");
    Scanner sc1 = new Scanner(new File("D:\\New folder\\test.txt"));
    while (sc1.hasNext()) 
	{
          String str1 = sc1.nextLine();
          System.out.println(str1);
        }
        sc1.close();

    // Reading a text file contents word by word using Scanner class
    System.out.println("Reading a text file word by word: ");
    Scanner sc2 = new Scanner(new File("D:\\New folder\\test.txt"));
    while (sc2.hasNext()) 
	{
          String str2 = sc2.next();
          System.out.println(str2);
        }
        sc2.close();
   }
}
Output :
Reading a text file contents line by line:
File Handling Program3
Reading a text file word by word:
File
Handling
Program3
Example : Write a java program to create a new file, write/store data in the created file, modify the stored contents, read/display the contents from the file using File handling concept.
import java.io.*;
class Example
{
    public static void main(String[] args)
    {
        try
        {
            // Creating new Text file
			
            File file = new File("D:\\New folder\\test1.txt");
              if (!file.exists())
                {
                  file.createNewFile();
                  System.out.println("File created Successfully.");
                }
				
                FileOutputStream fos=new FileOutputStream("D:\\New folder\\test1.txt");				
                // Writing contents to Text file
				
                String str="Welcome in your site Codershelpline";
                byte bt[]=str.getBytes();
                fos.write(bt);
                fos.close();
                //System.out.println("Writing into text file Complete!");
				
                FileInputStream fis = new FileInputStream("D:\\New folder\\test1.txt");                
                //Reading from Text file
                int i;
                while((i=fis.read())!=-1)
                {
                  System.out.print((char)i);
                }
                fis.close();
				
                fos=new FileOutputStream("D:\\New folder\\test1.txt");				
                // Modifying Text file
				
                str="\nThis site contains various topics in simpler form";
                bt=str.getBytes();
                fos.write(bt);
                fos.close();
                //System.out.println("\n Now Modification Completed!");
				
                fis = new FileInputStream("D:\\New folder\\test1.txt");				
                //Reading/displaying data from Text file
				
                while((i=fis.read())!=-1)
                {
                   System.out.print((char)i);
                }
                fis.close();
        }                    
                catch (IOException e)
                {
                   System.out.println("I/O Exception occurred.");
                }
     }
}

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Categories: Java

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