How to Split and Parse a Text File in Java

Question

What is the process to split and parse a text file using Java?

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class TextFileParser {
    public static void main(String[] args) {
        String filePath = "path/to/your/textfile.txt";
        List<String[]> parsedData = splitAndParseFile(filePath);
        parsedData.forEach(arr -> System.out.println(Arrays.toString(arr)));
    }

    public static List<String[]> splitAndParseFile(String filePath) {
        List<String[]> data = new ArrayList<>();
        try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = br.readLine()) != null) {
                // Splitting the line by commas (or any other delimiter)
                String[] parts = line.split(",");
                data.add(parts);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return data;
    }
}

Answer

In Java, splitting and parsing a text file involves reading the file line by line, splitting each line into parts based on a specific delimiter, and storing those parts in a structured format for further processing.

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class TextFileParser {
    public static void main(String[] args) {
        String filePath = "path/to/your/textfile.txt";
        List<String[]> parsedData = splitAndParseFile(filePath);
        parsedData.forEach(arr -> System.out.println(Arrays.toString(arr)));
    }

    public static List<String[]> splitAndParseFile(String filePath) {
        List<String[]> data = new ArrayList<>();
        try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
            String line;
            while ((line = br.readLine()) != null) {
                // Splitting the line by commas (or any other delimiter)
                String[] parts = line.split(",");
                data.add(parts);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return data;
    }
}

Causes

Understanding how to read files in Java.
Knowing how to split strings using delimiters.
Converting data into an appropriate format for processing.

Solutions

Use BufferedReader for efficient file reading.
Implement a loop to read lines.
Utilize String.split() method to handle line splitting.

Common Mistakes

Mistake: Using incorrect file paths which result in FileNotFoundException.

Solution: Ensure the file path is correct and accessible.

Mistake: Not handling exceptions, which can crash the application.

Solution: Use try-catch blocks to handle potential IOExceptions.

Mistake: Forgetting to split by the right delimiter, resulting in unexpected array sizes.

Solution: Confirm the correct delimiter used in the text file.

Helpers

Java file handling
Split text file in Java
Parse text file Java example
BufferedReader Java
String split method Java