Three ways to do this

• FileIutputStream and FileOutputStream
• DataInputStream and DataOutputStream
• BufferedInputStream and BufferedInputStream

FileIutputStream and FileOutputStream

package FileDemo;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class ReadAndWriteContentWithFile {
    public static void main(String[] args) throws IOException {
        try (FileOutputStream out = new FileOutputStream("contentFile.txt")) {
            for (int i = 1; i < 10; i++) {
                out.write(i);
            }
        }
        try (FileInputStream input = new FileInputStream("contentFile.txt")) {
            int v;
            while ((v = input.read()) != -1) {
                System.out.print(v);
            }
        }
    }
}

Output

123456789

DataInputStream and DataOutputStream

package FileDemo;

import java.io.*;

public class DataInputStreamAndDataOutputStreamDemo {
    public static void main(String[] args) throws IOException {
        try (DataOutputStream output = new DataOutputStream(new FileOutputStream("contentFile2.dat"))) {
            // Write student test scores to the file
            output.writeUTF("Andrew");
            output.writeDouble(85.5);
            output.writeUTF("Jim");
            output.writeDouble(185.5);
        }

        try (
                DataInputStream input =
                        new DataInputStream(new FileInputStream("contentFile2.dat"));
        ) {
            // Read student test scores from the file
            System.out.println(input.readUTF() + " " + input.readDouble());
            System.out.println(input.readUTF() + " " + input.readDouble());
        }
    }
}

Output

Andrew 85.5
Jim 185.5

BufferedInputStream and BufferedInputStream

package FileDemo;

import java.io.*;

public class BufferedOutputStreamAndBufferedInputStreamDemo {
    public static void main(String[] args) throws IOException {
        try (DataOutputStream output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("contentFile3.dat")))) {
            output.writeUTF("Andrew Programming");
            output.writeDouble(100.00);
        }


        try (DataInputStream input = new DataInputStream(new BufferedInputStream(new FileInputStream("contentFile3.dat")))) {
            System.out.println(input.readUTF());
            System.out.println(input.readDouble());
        }
    }
}

Output

Andrew Programming
100.0

Source Code

https://github.com/AndrewProgramming/LearnJavaByExample