Java file handling tutorial - Reading from a file

This tutorial demonstrates you the basic Java file handling concepts with code examples.

Tutorial info:

Name:	Java file handling tutorial
Total steps:	2
Category:	File handling
Date:	2009-04-27
Level:	Beginner
Product:	See complete product
Viewed:	30089

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Step 2 - Reading from a file

Java file handling tutorial

If everything is alright, you have successfully written some basic text into a file. Now it's time to read the file content back. Not surprisingly reading from a file is very similar to writing. We only need to use *Reader objects instead of *Writer objects. It means that you can use FileReader or BufferedReader. As a simple FileReader can handle only a single character or a character array it is more convenient to use the BufferedReader which can read a complete line from a file as a string. So using a BufferedReader we can read a text file line by line with the readln() method as you can see in this example:

Code: 
public String readFile() {
    String fileName = "c:\\test.txt";
    String LS = System.getProperty("line.separator");
    StringBuffer fileContent = new StringBuffer();
 
    try {
        FileReader fr = new FileReader(fileName);
        BufferedReader reader = new BufferedReader(new FileReader(fileName));
 
        String line;
        while ((line = reader.readLine()) != null) {
            fileContent.append(line).append(LS);
        }
 
    } catch (IOException e) {
        e.printStackTrace();
    }
 
    return fileContent.toString();
}
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I hope this article made a beginner java programmer life easier. Finally let's see how the complete Java program looks like:

Code: 
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
 
public class FileDemo {
 
    public static void main(String[] args) {
        FileDemo fd = new FileDemo();
        fd.writeFile();
        String txt = fd.readFile();
        System.out.println(txt);
    }
 
    public void writeFile() {
        String fileName = "c:\\test.txt";
 
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(fileName,true));
            writer.write("Test text.");
            writer.newLine();
            writer.write("Line2");
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 
    public String readFile() {
        String fileName = "c:\\test.txt";
        String LS = System.getProperty("line.separator");
        StringBuffer fileContent = new StringBuffer();
 
        try {
            FileReader fr = new FileReader(fileName);
            BufferedReader reader = new BufferedReader(new FileReader(fileName));
 
            String line;
            while ((line = reader.readLine()) != null) {
                fileContent.append(line).append(LS);
            }
 
        } catch (IOException e) {
            e.printStackTrace();
        }
 
        return fileContent.toString();
    }
}
 
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Tags: java file handling tutorial, java file handling, file handling tutorial, java, file

Java file handling tutorial - Table of contents
Step 1 - Java file handling basics
Step 2 - Reading from a file

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Java file handling tutorial - Reading from a file

Tutorial info:

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Step 2 - Reading from a file