When working with large files in Kotlin, handling them efficiently is crucial to avoid performance issues such as high memory usage and slow processing times. In this article, we explore different approaches to reading large files efficiently in Kotlin and compare them with Java. Table of contents Why Efficient File Reading Matters 1. Read Large […]
In this article, we will cover how to read, write, modify, delete, and list files in Kotlin and compare them with Java equivalents. Table of contents 1. Reading a File in Kotlin 2. Writing to a File in Kotlin 3. Modifying a File in Kotlin 4. Deleting a File in Kotlin 5. Listing Files in […]
This article shows the difference between r, r+, w, w+, a and a+ in Python open() function. Table of contents 1. Difference between r, r+, w, w+, a and a+ 2. What is + means in open()? 3. Difference between r and r+ in open() 3.1 Read a file with r 3.2 Read and write […]
This article shows how to append a text file in Python. Table of contents 1. Append to a file 2. Difference between a and a+ 3. Download Source Code 4. References P.S Tested with Python 3.8 1. Append to a file The a creates a new file or opens an existing file for writing; the […]
This article shows how to write a text file in Python. Table of contents 1. Write to a file – open() and close() 2. Write to a file – with statement 3. Write multiple lines to a file 4. Working with two files 5. Find and replace in a file 6. Download Source Code 7. […]
This article shows how to read a text file in Python. Table of contents 1. Read a file using open() and close() 2. Read a file using with statement 3. Read a file using try-finally 4. Read a file line by line 5. Read a file and skip the first line 6. Default open mode […]
This article shows you how to add, check and remove the byte order mark (BOM) from a UTF-8 file. The UTF-8 representation of the BOM is the byte sequence 0xEF, 0xBB, 0xBF (hexadecimal), at the beginning of the file. 1. Add BOM to a UTF-8 file 2. Check if a file contains UTF-8 BOM 3. […]
Long live the Scanner class, a few examples for self-reference. 1. Read Input 1.1 Read input from the console. JavaScanner1.java package com.mkyong.io; import java.util.Scanner; public class JavaScanner1 { public static void main(String[] args) { try (Scanner scanner = new Scanner(System.in)) { System.out.print("Please enter your name: "); String input = scanner.nextLine(); System.out.println("name : " + input); […]
In Java, we can use the Apache Commons IO ReversedLinesFileReader to read the last few lines of a File. pom.xml <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.6</version> </dependency> 1. Test Data A server log file sample d:\\server.log a b c d 1 2 3 4 5 2. Read Last Line 2.1 Read the last 3 lines of a […]
This article focus on a few of the commonly used methods to read a file in Java. Files.lines, return a Stream (Java 8) Files.readString, returns a String (Java 11), max file size 2G. Files.readAllBytes, returns a byte[] (Java 7), max file size 2G. Files.readAllLines, returns a List<String> (Java 8) BufferedReader, a classic old friend (Java […]
In Java, we can use Files.readAllBytes to read a file. byte[] content = Files.readAllBytes(Paths.get("app.log")); System.out.println(new String(content)); 1. Text File A Java example to write and read a normal text file. FileExample1.java package com.mkyong.calculator; import java.io.IOException; import java.nio.charset.Charset; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Paths; import java.util.Arrays; import java.util.List; public class FileExample1 { public static void main(String[] […]
In Java, there are few ways to read a file line by line into a List 1. Java 8 stream List<String> result; try (Stream<String> lines = Files.lines(Paths.get(fileName))) { result = lines.collect(Collectors.toList()); } 2. Java 7 Files.readAllLines(new File(fileName).toPath(), Charset.defaultCharset()); 3. Classic BufferedReader example. List<String> result = new ArrayList<>(); BufferedReader br = null; try { br = […]
Python example to read a log file, line by line into a list. # With ‘\n’, [‘1\n’, ‘2\n’, ‘3’] with open(‘/www/logs/server.log’) as f: content = f.readlines() # No ‘\n’, [‘1’, ‘2’, ‘3’] with open(‘/www/logs/server.log’) as f: content = f.read().splitlines() 1. Read File -> List 1.1 A dummy log file. d:\\server.log a b c d 1 […]
This article explains the Java 8 Stream.flatMap and how to use it. Topic What is flatMap? Why flat a Stream? flatMap example – Find a set of books. flatMap example – Order and LineItems. flatMap example – Splits the line by spaces. flatMap and Primitive type 1. What is flatMap()? 1.1 Review the below structure. […]
In Java 8, you can use Files.lines to read file as Stream. c://lines.txt – A simple text file for testing line1 line2 line3 line4 line5 1. Java 8 Read File + Stream TestReadFile.java package com.mkyong.java8; import java.io.IOException; import java.nio.file.Files; import java.nio.file.Paths; import java.util.stream.Stream; public class TestReadFile { public static void main(String args[]) { String fileName […]
This article covers 3 ways to read a text file line by line : Java NIO libraries – FileChannel to read the files. It is a non-blocking mode of reading files BufferedReader – Which is a blocking operation i.e it blocks any other read/write request to the file until it has completed the task. Apache […]
In Java, we can use getResourceAsStream or getResource to read a file or multiple files from a resources folder or root of the classpath. The getResourceAsStream method returns an InputStream. // the stream holding the file content InputStream is = getClass().getClassLoader().getResourceAsStream("file.txt"); // for static access, uses the class name directly InputStream is = JavaClassName.class.getClassLoader().getResourceAsStream("file.txt"); The […]
This article shows how to read and parse a comma-separated values (CSV) file. Topics: CSV file and RFC 4180 OpenCSV – Read and Parse CSV file OpenCSV – Convert CSV file to Object Parse CSV file Challenges – Embedded commas, double quotes, and line breaks Single class to read and parse a CSV file String#split […]
In Java, we use FileInputStream to read bytes from a file, such as an image file or binary file. Topics FileInputStream – Read a file FileInputStream – Remaining bytes FileInputStream – Better performance FileInputStream vs BufferedInputStream InputStreamReader – Convert FileInputStream to Reader FileInputStream – Read a Unicode file Note However, all the below examples use […]
This article shows how to convert a file into a hexadecimal (hex) representative format. for example, below is a text file. /path/to/text.txt ABCDEFG 12345678 !@#$%^&*() Testing only And we will convert the above file into the following hex format. 41 42 43 44 45 46 47 0D 0A 31 32 33 34 35 36 | […]
In Java, we can use Files.readAllBytes(path) to convert a File object into a byte[]. import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; String filePath = "/path/to/file"; // file to byte[], Path byte[] bytes = Files.readAllBytes(Paths.get(filePath)); // file to byte[], File -> Path File file = new File(filePath); byte[] bytes = Files.readAllBytes(file.toPath()); P.S The NIO Files class is […]
In Java, the InputStreamReader accepts a charset to decode the byte streams into character streams. We can pass a StandardCharsets.UTF_8 into the InputStreamReader constructor to read data from a UTF-8 file. import java.nio.charset.StandardCharsets; //… try (FileInputStream fis = new FileInputStream(file); InputStreamReader isr = new InputStreamReader(fis, StandardCharsets.UTF_8); BufferedReader reader = new BufferedReader(isr) ) { String str; […]
Here is another example to show how to read a file in Java with BufferedInputStream and DataInputStream classes. The readLine() from the type DataInputStream is deprecated. Sun officially announced this method can not convert property from bytes to characters. It’s advised to use BufferedReader. You may interest to read this How to read file from […]
In this article, we will show you how to use java.io.BufferedReader to read content from a file Note Read this different ways read a file 1. Files.newBufferedReader (Java 8) In Java 8, there is a new method Files.newBufferedReader(Paths.get(“file”)) to return a BufferedReader filename.txt A B C D E FileExample1.java package com.mkyong; import java.io.BufferedReader; import java.io.IOException; […]
