Compare two file content if it is equal or not !!

Using FileUtils:

1. import java.io.File;
2. import org.apache.commons.io.FileUtils;
3. 
   
4. public class CompareFileContent {
5. public static void main(String[] args) throws Exception {
6. File file1 = new File("D:\\data.txt");
7. File file2 = new File("D:\\data1.txt");
8. boolean isEqual = FileUtils.contentEquals(file1, file2);
9. System.out.println(isEqual == true ? "equal" : "not equal");
10. }
11. }

Output:

equal

data.txt - file:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line 

irrespective of amount of data that a file is having.

data1.txt - file:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line 

irrespective of amount of data that a file is having.

Count the characters in a file or size of a file !!

Using File:

1. import java.io.File;
2. 
   
3. public class CountCharInFile {
4. public static void main(String[] args) throws Exception {
5. File file = new File("D:\\data.txt");
6. int fileDataLen = (int) file.length();
7. System.out.println(fileDataLen);
8. }
9. }

Output: 

241

data.txt file:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line 

irrespective of amount of data that a file is having.

Read properties from an xml file !!

Using Properties class:

1. import java.io.File;
2. import java.io.FileInputStream;
3. import java.util.Enumeration;
4. import java.util.Properties;
5. 
   
6. public class ReadPropertiesXmlFile {
7. public static void main(String[] args) throws Exception {
8. File file = new File("D:\\prop.xml");
9. FileInputStream fileInput = new FileInputStream(file);
10. Properties properties = new Properties();
11. properties.loadFromXML(fileInput);
12. fileInput.close();
13. 
    
14. Enumeration enuKeys = properties.keys();
15. while (enuKeys.hasMoreElements()) {
16. String key = (String) enuKeys.nextElement();
17. String value = properties.getProperty(key);
18. System.out.println(key + ": " + value);
19. }
20. }
21. }

Output:
favoriteSeason: spring
favoriteDay: today
favoriteFruit: apple

prop.xml - file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<comment>Here are some favorites</comment>
<entry key="favoriteSeason">spring</entry>
<entry key="favoriteFruit">apple</entry>
<entry key="favoriteDay">today</entry>

</properties>

Read the data from properties file !!

Using Properties class:

1. import java.io.File;
2. import java.io.FileInputStream;
3. import java.io.IOException;
4. import java.util.Enumeration;
5. import java.util.Properties;
6. 
   
7. public class ReadPropertiesFiles {
8. public static void main(String[] args) throws IOException {
9. 
   
10. File file = new File("D:\\contacts.properties");
11. FileInputStream fis = new FileInputStream(file);
12. Properties prop = new Properties();
13. prop.load(fis);
14. fis.close();
15. 
    
16. Enumeration enuKeys = prop.keys();
17. while (enuKeys.hasMoreElements()) {
18. String key = (String) enuKeys.nextElement();
19. String value = prop.getProperty(key);
20. System.out.println(key + " = " + value);
21. }
22. }
23. }

Output:
delhi = sumit
japan = chet
bangalore = raju
chennai = ishaan

Read file using BufferedReader !!

Using BufferedReader:

1. import java.io.File;
2. import java.io.FileReader;
3. import java.io.BufferedReader;
4. 
   
5. public class ReadFileByBufferedReader {
6. 
   
7. public static void main(String[] args) throws Exception {
8. File file = new File("D://data.txt");
9. FileReader fr = new FileReader(file);
10. BufferedReader br = new BufferedReader(fr);
11. StringBuffer sb = new StringBuffer();
12. 
    
13. String line = br.readLine(); // read the line
14. while (null != line) {
15. sb.append(line); // append the line
16. sb.append("\n");
17. line = br.readLine(); // read the line
18. }
19. System.out.println(sb.toString());
20. fr.close();
21. }
22. }

Output:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line 

irrespective of amount of data that a file is having.

Read data from a file using BufferedReader !!

Using BufferedReader:

1. import java.io.File;
2. import java.io.FileReader;
3. import java.io.BufferedReader;
4. 
   
5. public class ReadFileByBufferedReader {
6. 
   
7. public static void main(String[] args) {
8. try {
9. File file = new File("D://data.txt");
10. FileReader fr = new FileReader(file);
11. BufferedReader br = new BufferedReader(fr);
12. String line = br.readLine(); // read the line
13. while (null != line) {
14. System.out.println(line); // print the line
15. line = br.readLine(); // read the next line
16. }
17. fr.close();
18. } catch (Exception e) {
19. System.out.println("excepton occured in " + e);
20. }
21. }
22. }

Note: extension support .java/.txt/.xml/.yml/.html/.css etc file

Output:
Hi guys !!
This is Ishaan from India.
and I'm reading the data from a text file line by line using BufferedReader.
Isn't it interesting !! to read the data from a file line by line
irrespective of amount of data that a file is having.

II Approach:

1. import java.io.File;
2. import java.io.FileReader;
3. import java.io.BufferedReader;
4. 
   
5. public class ReadFileByBufferedReader {
6. 
   
7. public static void main(String[] args) {
8. File file = null;
9. FileReader fr = null;
10. BufferedReader br = null;
11. try {
12. file = new File("D://data.txt");
13. fr = new FileReader(file);
14. br = new BufferedReader(fr);
15. String line = br.readLine(); // read the next line
16. 
    
17. while (line != null) {
18. System.out.println(line); // print the line
19. line = br.readLine(); // read the next line
20. }
21. } catch (Exception e) {
22. System.out.println("excepton occured in " + e);
23. } finally {
24. try {
25. if (fr != null) {
26. fr.close();
27. }
28. if (br != null) {
29. br.close();
30. }
31. } catch (Exception e) {
32. System.out.println("excepton occured in finally block " + e);
33. }
34. }
35. }
36. // support .java/.txt/.xml/.yml/.html/.css etc file
37. }

Read data from a file using FileReader class !!

Read file using FileReader:

1. import java.io.File;
2. import java.io.FileReader;
3. 
   
4. public class ReadFileByFileReader {
5. public static void main(String[] args) {
6. try {
7. File file = new File("D:\\data.txt");
8. FileReader fr = new FileReader(file);
9. 
   
10. int length = (int) file.length();
11. char c[] = new char[length];
12. 
    
13. fr.read(c);
14. String data = new String(c);
15. 
    
16. System.out.println(data);
17. fr.close();
18. } catch (Exception e) {
19. System.out.println("excepton occured in " + e);
20. }
21. }
22. }

Output:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line 

irrespective of amount of data that a file is having.

Read / Write data in a file for transient field using ObjectOutputStream

Using ObjectOutputStream class & transient keyword:

1. import java.io.File;
2. import java.io.FileOutputStream;
3. import java.io.ObjectOutputStream;
4. import java.io.Serializable;
5. 
   
6. class Employee implements Serializable {
7. 
   
8. private static final long serialVersionUID = 1L;
9. int id;
10. String name;
11. // double salary;
12. transient double salary;
13. 
    
14. public Employee(int id, String name, double salary) {
15. this.id = id;
16. this.name = name;
17. this.salary = salary;
18. }
19. 
    
20. @Override
21. public String toString() {
22. return "[id: " + id + ", name: " + name + ", salary: " + salary + "]";
23. }
24. }
25. 
    
26. public class WriteByObjectOutputStreamExe {
27. 
    
28. public static void main(String[] args) throws Exception {
29. File file = new File("D:\\data1.txt");
30. FileOutputStream fileStream = new FileOutputStream(file);
31. ObjectOutputStream objStream = new ObjectOutputStream(fileStream);
32. 
    
33. Employee e1 = new Employee(101, "suresh", 2000);
34. 
    
35. objStream.writeObject(e1);
36. objStream.flush();
37. objStream.close();
38. }
39. }

Output:
ͭ sr  com.ishaan.filehandling.Employee        I idL namet Ljava/lang/String;xp   et suresh

Read transient field data from a file using ObjectInputStream:

1. import java.io.File;
2. import java.io.FileInputStream;
3. import java.io.ObjectInputStream;
4. 
   
5. public class ReadFileByObjectInputStreamExe {
6. 
   
7. public static void main(String[] args) throws Exception {
8. File file = new File("D:\\data1.txt");
9. FileInputStream fileStream = new FileInputStream(file);
10. ObjectInputStream objStream = new ObjectInputStream(fileStream);
11. 
    
12. Employee emp = (Employee) objStream.readObject();
13. 
    
14. System.out.println(emp.toString());
15. objStream.close();
16. }
17. }

Output: 
[id: 101, name: suresh, salary: 0.0]

Write data from properties to xml file !!

Using Properties class:

1. import java.io.File;
2. import java.io.FileOutputStream;
3. import java.util.Properties;
4. 
   
5. public class WritePropertiesXmlFile {
6. public static void main(String[] args) throws Exception {
7. Properties properties = new Properties();
8. properties.setProperty("suresh", "2000");
9. properties.setProperty("mahesh", "1200");
10. properties.setProperty("ritesh", "2100");
11. 
    
12. File file = new File("D:\\test2.xml");
13. FileOutputStream fileOut = new FileOutputStream(file);
14. properties.storeToXML(fileOut, "balance-sheet");
15. fileOut.close();
16. }
17. }

Output:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<comment>balance-sheet</comment>
<entry key="ritesh">2100</entry>
<entry key="suresh">2000</entry>
<entry key="ishaan">0000</entry>
<entry key="mahesh">1200</entry>
</properties>

Write the data in properties file !!

Using Properties class:

1. import java.io.File;
2. import java.io.FileOutputStream;
3. import java.io.IOException;
4. import java.util.Properties;
5. 
   
6. public class WritePropertiesFiles {
7. 
   
8. public static void main(String[] args) throws IOException {
9. Properties prop = new Properties();
10. prop.setProperty("bangalore", "raju");
11. prop.setProperty("delhi", "ritesh");
12. prop.setProperty("chennai", "ishaan");
13. prop.setProperty("japan", "chet");
14. 
    
15. File file = new File("D:\\contacts.properties");
16. FileOutputStream fileStream = new FileOutputStream(file);
17. prop.store(fileStream, "store the contacts");
18. fileStream.close();
19. }
20. }

Output:
#store the contacts
#Sun Apr 29 20:22:15 IST 2018
delhi=ritesh
japan=chet
chennai=ishaan
bangalore=raju

Write the data using PrintWriter in java !!

Using PrintWriter:

1. import java.io.File;
2. import java.io.FileWriter;
3. import java.io.PrintWriter;
4. import java.io.IOException;
5. 
   
6. public class WriteByPrintWriterExe {
7. public static void main(String[] args) throws IOException {
8. File file = new File("D:\\data1.txt");
9. FileWriter fw = new FileWriter(file);
10. PrintWriter pw = new PrintWriter(fw);
11. 
    
12. for (int i = 0; i < 5; i++) {
13. pw.write("using PrintWriter !!");
14. pw.append("\n");
15. }
16. pw.close();
17. }
18. }

Output:
using PrintWriter !!
using PrintWriter !!
using PrintWriter !!
using PrintWriter !!
using PrintWriter !!

Read file using ObjectInputStream !!

Using ObjectInputStream:

1. import java.io.File;
2. import java.io.FileInputStream;
3. import java.io.ObjectInputStream;
4. 
   
5. public class ReadFileByObjectInputStreamExe {
6. 
   
7. public static void main(String[] args) throws Exception {
8. File file = new File("D:\\data1.txt");
9. FileInputStream fileStream = new FileInputStream(file);
10. ObjectInputStream objStream = new ObjectInputStream(fileStream);
11. 
    
12. Employee emp = (Employee) objStream.readObject();
13. 
    
14. System.out.println(emp.toString());
15. objStream.close();
16. }
17. }

Employee.java:

1. import java.io.Serializable;
2. class Employee implements Serializable {
3. 
   
4. private static final long serialVersionUID = 1L;
5. int id;
6. String name;
7. double salary;
8. // transient double salary;
9. 
   
10. public Employee(int id, String name, double salary) {
11. this.id = id;
12. this.name = name;
13. this.salary = salary;
14. }
15. 
    
16. @Override
17. public String toString() {
18. return "[id: " + id + ", name: " + name + ", salary: " + salary + "]";
19. }
20. }

Output: 
[id: 101, name: suresh, salary: 2000.0]

Write data in a file using ObjectOutputStream !!

Using ObjectOutputStream:

1. import java.io.File;
2. import java.io.FileOutputStream;
3. import java.io.ObjectOutputStream;
4. import java.io.Serializable;
5. 
   
6. class Employee implements Serializable {
7. 
   
8. private static final long serialVersionUID = 1L;
9. int id;
10. String name;
11. double salary;
12. // transient double salary;
13. 
    
14. public Employee(int id, String name, double salary) {
15. this.id = id;
16. this.name = name;
17. this.salary = salary;
18. }
19. 
    
20. @Override
21. public String toString() {
22. return "[id: " + id + ", name: " + name + ", salary: " + salary + "]";
23. }
24. }
25. 
    
26. public class WriteByObjectOutputStreamExe {
27. 
    
28. public static void main(String[] args) throws Exception {
29. File file = new File("D:\\data1.txt");
30. FileOutputStream fileStream = new FileOutputStream(file);
31. ObjectOutputStream objStream = new ObjectOutputStream(fileStream);
32. 
    
33. Employee e1 = new Employee(101, "suresh", 2000);
34. 
    
35. objStream.writeObject(e1);
36. objStream.flush();
37. objStream.close();
38. }
39. }

Output:

ͭ sr  com.ishaan.filehandling.Employee        I idD salaryL namet Ljava/lang/String;xp   e@ࠀ     t suresh

Write the data in a file using OutputStreamWriter !!

Using OutputStreamWriter: 

1. import java.io.File;
2. import java.io.FileOutputStream;
3. import java.io.OutputStreamWriter;
4. 
   
5. public class WriteByOutputStreamWriterExe {
6. 
   
7. public static void main(String[] args) throws Exception {
8. 
   
9. File file = new File("D:\\data1.txt");
10. FileOutputStream fileStream = new FileOutputStream(file);
11. OutputStreamWriter outputStream = new OutputStreamWriter(fileStream);
12. 
    
13. for (int i = 0; i < 5; i++) {
14. outputStream.write("using OutputStreamWriter !!");
15. outputStream.append("\n");
16. }
17. outputStream.close();
18. }
19. }

Output: 

using OutputStreamWriter !!
using OutputStreamWriter !!
using OutputStreamWriter !!
using OutputStreamWriter !!
using OutputStreamWriter !!

Write the data in a file using OutputStreamWriter !!

Using OutputStreamWriter: 

1. import java.io.File;
2. import java.io.FileOutputStream;
3. import java.io.OutputStreamWriter;
4. import java.io.BufferedWriter;
5. 
   
6. public class WriteByOutputStreamWriterExe {
7. 
   
8. public static void main(String[] args) throws Exception {
9. 
   
10. File file = new File("D:\\data1.txt");
11. FileOutputStream fileStream = new FileOutputStream(file);
12. OutputStreamWriter outputStream = new OutputStreamWriter(fileStream);
13. BufferedWriter bw = new BufferedWriter(outputStream);
14. 
    
15. for (int i = 0; i < 5; i++) {
16. bw.write("Using FileOutputStream. Isn't is interesting !! :)");
17. bw.newLine();
18. }
19. bw.close();
20. }
21. }

Output: 
Using FileOutputStream. Isn't is interesting !! :)
Using FileOutputStream. Isn't is interesting !! :)
Using FileOutputStream. Isn't is interesting !! :)
Using FileOutputStream. Isn't is interesting !! :)
Using FileOutputStream. Isn't is interesting !! :)

Write the data in a file using BufferedWriter !!

Using BufferedWriter:

1. import java.io.File;
2. import java.io.FileWriter;
3. import java.io.BufferedWriter;
4. import java.io.IOException;
5. 
   
6. public class WriteByBufferedWriterExe {
7. 
   
8. public static void main(String[] args) throws IOException {
9. String contents = "writing data using BufferedWriter. Isn't it interesting !!)";
10. 
    
11. File file = new File("D:\\data1.txt");
12. FileWriter fw = new FileWriter(file);
13. BufferedWriter bw = new BufferedWriter(fw);
14. 
    
15. for (int i = 0; i < 5; i++) {
16. bw.write(contents);
17. bw.newLine(); // bw.append("\n");
18. }
19. bw.close();
20. }
21. }

Output:

writing data using BufferedWriter. Isn't it interesting !! :)
writing data using BufferedWriter. Isn't it interesting !! :)
writing data using BufferedWriter. Isn't it interesting !! :)
writing data using BufferedWriter. Isn't it interesting !! :)
writing data using BufferedWriter. Isn't it interesting !! :)

Write the data in a file using Files class !!

Using Files class:

1. import java.nio.file.Files;
2. import java.nio.file.Paths;
3. import java.nio.file.Path;
4. import java.io.IOException;
5. 
   
6. public class WriteByFiles {
7. public static void main(String[] args) throws IOException {
8. String content = "writing data to data1.txt file using Files class !!";
9. String uri = "D:\\data1.txt";
10. Path path = Paths.get(uri);
11. Files.write(path, content.getBytes());
12. }
13. }

Output:
writing data to data1.txt file using Files class !!

Write same data multiple times in a file using FileWriter class !!

Using FileWriter:

1. import java.io.File;
2. import java.io.FileWriter;
3. 
   
4. public class WriteByFileWriterExe {
5. 
   
6. public static void main(String[] args) throws Exception {
7. File file = new File("D:\\data1.txt");
8. FileWriter fw = new FileWriter(file);
9. 
   
10. for (int i = 0; i < 5; i++) {
11. fw.write("using FileWriter !!");
12. fw.append("\n");
13. }
14. fw.close();
15. }
16. }

Output:

using FileWriter !!

using FileWriter !!

using FileWriter !!

using FileWriter !!

using FileWriter !!

Write the data in a file using FileWriter class !!

Using FileWriter: 

1. import java.io.File;
2. import java.io.FileWriter;
3. import java.io.IOException;
4. 
   
5. public class WriteByFileWriter {
6. 
   
7. public static void main(String[] args) throws IOException {
8. File file = new File("D:\\data1.txt");
9. FileWriter contacts = new FileWriter(file);
10. contacts.write("suresh - 9999999999\n");
11. contacts.write("ritesh - 0000000000\n");
12. contacts.write("mahesh - 8888888888");
13. contacts.close();
14. }
15. }

Output:

suresh - 9999999999

ritesh - 0000000000

mahesh - 8888888888

Difference b/w FileOutputStream and FileWriter in java ?

• FileOutputStream class is meant for writing streams of raw bytes / java object such as image data.
• FileWriter class is meant for writing character data to a file. 

• Similarity b/w FileOutputStream & FileWriter: Both the classes belongs to java.io package