Reading a plain text file in Java

Question

It seems there are different ways to read and write data of files in Java.

I want to read ASCII data from a file. What are the possible ways and their differences?

Answer 1

ASCII is a TEXT file so you would use Readers for reading. Java also supports reading from a binary file using InputStreams. If the files being read are huge then you would want to use a BufferedReader on top of a FileReader to improve read performance.

Go through this article on how to use a Reader

I'd also recommend you download and read this wonderful (yet free) book called Thinking In Java

In Java 7:

new String(Files.readAllBytes(...))

 or

Files.readAllLines(...)

In Java 8:

Files.lines(..).forEach(...)

Answer 2

Read a plain text file:

Java Code:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.FileInputStream;
import java.io.FileReader;
 
public class Exercise12 {
 
    public static void main(String a[]){
        StringBuilder sb = new StringBuilder();
        String strLine = "";
        try {
             BufferedReader br = new BufferedReader(new FileReader("/home/students/test.txt"));
             while (strLine != null)
             {
                sb.append(strLine);
                sb.append(System.lineSeparator());
                strLine = br.readLine();
                System.out.println(strLine);
            }
             br.close();
        } catch (FileNotFoundException e) {
            System.err.println("File not found");
        } catch (IOException e) {
            System.err.println("Unable to read the file.");
        }
     }
}