Venkatesh-Java File concept
JAVA FILE CONCEPT
1) Write a program to create a new file using File class.
Code :
import java.io.File;
import java.io.IOException;
class createfileEx
{
public static void main(String[] args)
{
System.out.println("Question 1: Create a New File using File class.");
try
{
File venkatfile = new File("sample.txt");
if (venkatfile.createNewFile())
{
System.out.println("File created: " + venkatfile.getName());
} else
{
System.out.println("File already exists.");
}
} catch (IOException e)
{
e.printStackTrace();
}
}
}
Output :
2) Write a program to check if a file exists.
Code :
import java.io.File;
class CheckFileExist {
public static void main(String[] args) {
System.out.println("Question 2: Check if a File Exists.");
File file = new File("sample.txt");
if (file.exists()) {
System.out.println("File exists.");
} else {
System.out.println("File does not exist.");
}
}
}
Output :
3) Write a program to write text into a file using FileWriter.
Code :
import java.io.FileWriter;
import java.io.IOException;
class WriteFileExample {
public static void main(String[] args) {
System.out.println("Question 3: Write Text into a File using FileWriter.");
try {
FileWriter writer = new FileWriter("sample.txt");
writer.write("Hello, this is a test file.\nWelcome to Java File Handling.");
writer.close();
System.out.println("Successfully wrote to the file.");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
4) Write a program to read text from a file using FileReader.
Code :
import java.io.FileReader;
import java.io.IOException;
class ReadFileExample {
public static void main(String[] args) {
System.out.println("Question 4: Read Text from a File using FileReader.");
try {
FileReader reader = new FileReader("sample.txt");
int ch;
while ((ch = reader.read()) != -1) {
System.out.print((char) ch);
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
5) Write a program to read text from a file line by line using BufferedReader.
Code :
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
class ReadLineExample {
public static void main(String[] args) {
System.out.println("Question 5: Read File Line by Line using BufferedReader.");
try {
BufferedReader br = new BufferedReader(new FileReader("sample.txt"));
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
6) Write a program to append text to a file without overwriting.
Code :
import java.io.FileWriter;
import java.io.IOException;
class AppendFileExample {
public static void main(String[] args) {
System.out.println("Question 6: Append Text to a File without Overwriting.");
try {
FileWriter writer = new FileWriter("sample.txt", true);
writer.write("\nThis line is appended.");
writer.close();
System.out.println("Text appended successfully.");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
7) Write a program to count number of words in a text file.
v
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
class WordCountExample {
public static void main(String[] args) {
System.out.println("Question 7: Count Number of Words in a File.");
int wordCount = 0;
try {
BufferedReader br = new BufferedReader(new FileReader("sample.txt"));
String line;
while ((line = br.readLine()) != null) {
String[] words = line.split("\\s+");
wordCount += words.length;
}
br.close();
System.out.println("Total words: " + wordCount);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
8) Write a program to count number of lines in a file.
Code :
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
class LineCountExample {
public static void main(String[] args) {
System.out.println("Question 8: Count Number of Lines in a File.");
int lineCount = 0;
try {
BufferedReader br = new BufferedReader(new FileReader("sample.txt"));
while (br.readLine() != null) {
lineCount++;
}
br.close();
System.out.println("Total lines: " + lineCount);
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
9) Write a program to copy contents from one file to another.
Code :
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
class CopyFileExample {
public static void main(String[] args) {
System.out.println("Question 9: Copy Contents from One File to Another.");
try {
FileReader fr = new FileReader("sample.txt");
FileWriter fw = new FileWriter("copy.txt");
int ch;
while ((ch = fr.read()) != -1) {
fw.write(ch);
}
fr.close();
fw.close();
System.out.println("File copied successfully.");
} catch (IOException e) {
e.printStackTrace();
}
}
}
Output :
10) Write a program to serialize and deserialize an object (save and read object from file).
Code :
import java.io.*;
class Student implements Serializable {
String name;
int age;
public Student(String name, int age) {
this.name = name;
this.age = age;
}
}
class SerializationExample {
public static void main(String[] args) {
System.out.println("Question 10: Serialize and Deserialize an Object.");
String filename = "student.ser";
// Serialize
try {
Student s1 = new Student("John", 21);
FileOutputStream fos = new FileOutputStream(filename);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(s1);
oos.close();
fos.close();
System.out.println("Object serialized successfully.");
} catch (IOException e) {
e.printStackTrace();
}
// Deserialize
try {
FileInputStream fis = new FileInputStream(filename);
ObjectInputStream ois = new ObjectInputStream(fis);
Student s2 = (Student) ois.readObject();
ois.close();
fis.close();
System.out.println("Object deserialized successfully.");
System.out.println("Name: " + s2.name + ", Age: " + s2.age);
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
}
}
Output :
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