java file reader construct input

In Java, you can use the BufferedReader class from the java.io package to read data from a file using a construct that takes an InputStreamReader as input. The InputStreamReader class is a bridge from byte streams to character streams, and it reads bytes and decodes them into characters using a specified character set.

Here's an example of how to use the BufferedReader and InputStreamReader classes to read data from a file in Java:

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) {
        String fileName = "path/to/file.txt";
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(new FileInputStream(fileName), "UTF-8"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this example, a BufferedReader is created with an InputStreamReader as input. The InputStreamReader is created with a FileInputStream and a character set (in this case, "UTF-8"). The BufferedReader is then used to read lines from the file, and each line is printed to the console.

This code will read data from the file and print it to the console. You can use the BufferedReader and InputStreamReader classes to read data from a file in Java.