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File Handling:
what is file?? File is a collection of data which is store on secondary devices(harddisk,pendrive, flopy, cd etc..).
*There are two part in file: 1-filename 2-extension
extension define which software is suportable to open your file.
rishi.txt
filename: rishi extenssion: .txt
This file may be open with notepad.
File Handling Operations:-
create file write file read file append file delete file
1- creating file import java.io.*; class FileCreate { public static void main(String[] arg) { try { String x="D:/abc/xyz/jay.txt"; // String x="jay.txt"; then file will create in class folder File fl = new File(x);
fl.createNewFile(); SOP("File create successfully"); } catch(Exception ex) { System.out.println(" Path is incorrect "+ex); }
} }
2- write into file
import java.io.*; class WiteFile { public static void main(String[] arg) { try { String path = "d:/javafile/abc.txt"; File fl = new File(path);
FileWriter fw=new FileWriter(fl); BufferedWriter bw=new BufferedWriter(fw);
bw.write("jayprakash"); bw.newLine(); bw.write("monika"); bw.write("java programing");
for(int i=1;i<=100;i++) { bw.write(" "+i); }
bw.close(); System.out.println("Writing is completed");
}catch(Exception ex){ system.out.println("Error: "+ex);
Exercise: write java program to write 1 to 100000 number into a file.
import java.io.*; class LakhNumber { public static void main(String[] arg) { try { String path = "d:/javafile/abc.txt"; File fl = new File(path); FileWriter fw=new FileWriter(fl); BufferedWriter bw=new BufferedWriter(fw); for(int i=1;i<=100000;i++) {
system.out.println("Error: "+ex); } }
4- append in to file: There is same code write and append but difference is:
FileWriter fw=new FileWriter(fl.getAbsoluteFile() , true);
import java.io.*; try { String path = "d:\abc\siddarth.txt"; File fl = new File(path); if (!fl.exists()) { fl.createNewFile(); } FileWriter fw=new FileWriter(fl.getAbsoluteFile()); BufferedWriter bw=new BufferedWriter(fw);
String contents="Hello jayprakash"; bw.write(contents); bw.close();
System.out.println("Writing is completed"); }catch(Exception ex){ system.out.println("Error: "+ex); } }
5- remove file
import java.io.*; try { String path = "d:\abc\siddarth.txt"; File fl = new File(path);
fl.delete(); System.out.println("delete success");
}catch(Exception ex){ system.out.println("Error: "+ex); } }
Example:
1-There is a file in which small letter, capital latter, and digit such as
dsafrqemnfjkhhgGfytrYUHGkjghjfTYryUGjhBVhgFtyRyGjhG2323 323 kjguYTRyt
Now Write a java pragarm to seperate into three file capital, small and digit.
2- Write a program to enter customer name, mobile no and product(name,rate,quantity). print his bill into file.
3- There is file in which have so many line. Write a program to show how much time a word available.
6- change the content of file
7- there is a file in which even and odd numbers. write a program to seperate these number into even.txt and odd.txt file.
