Java Read Files

In Java, you can read files using the FileReader and BufferedReader classes.

Here's an example:
 

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class ReadFileExample {
    public static void main(String[] args) {
        try {
            FileReader fileReader = new FileReader("input.txt");
            BufferedReader bufferedReader = new BufferedReader(fileReader);
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                System.out.println(line);
            }
            bufferedReader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this example, we create a FileReader object for a file named "input.txt". We also create a BufferedReader object, which allows us to read the file in a buffered manner, improving performance.

We then use a while loop to read each line from the file using the readLine() method, which returns null when the end of the file is reached. We print each line to the console using the println() method of the System.out object.

Finally, we close the BufferedReader object to release any resources held by the object.

If an IOException occurs while reading the file, we catch it and print the stack trace.

Note that the file must exist in the specified path for this code to work. If the file does not exist, a FileNotFoundException will be thrown.

You can also read binary data from files using the FileInputStream and BufferedInputStream classes, as shown in the following example:

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class ReadBinaryFileExample {
    public static void main(String[] args) {
        try {
            FileInputStream fileInputStream = new FileInputStream("image.jpg");
            BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream);
            byte[] data = new byte[1024];
            int bytesRead;
            while ((bytesRead = bufferedInputStream.read(data, 0, 1024)) != -1) {
                // process data here
            }
            bufferedInputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this example, we create a FileInputStream object for a file named "image.jpg". We also create a BufferedInputStream object, which allows us to read the file in a buffered manner, improving performance.

We then use a while loop to read binary data from the file using the read() method of the BufferedInputStream object. The read() method returns the number of bytes read, or -1 if the end of the file is reached. We process the data in the loop as necessary.

Finally, we close the BufferedInputStream object to release any resources held by the object.

Note that the file must exist in the specified path for this code to work. If the file does not exist, a FileNotFoundException will be thrown.