5 Difference between BufferedReader and Scanner class in Java? Example

Hello guys, welcome to my blog. Today, we'll discuss another interesting Java interview question, BufferedReader vs Scanner. It's not only important from an interview point of view but also to work efficiently with Java. Even though both BufferedReader and Scanner can read a file or user input from the command prompt in Java, there are some significant differences between them. One of the main differences between BufferedReader and Scanner class is that the former class is meant to just read String or text data while the Scanner class is meant to both read and parse text data into Java primitive types like int, short, float, double, and long.

How to read a file line by line in Java? BufferedReader Example

Hello Java Programmers, if you are looking for a way to read a file line by line in Java then don't worry, Java provides java.io package in JDK API for reading File in Java from File system e.g. C:\ or D:\ drive in Windows or any other directory in UNIX. First, you can use FileInputStream to open a file for reading. FileInputStream takes a String parameter which is a path for the file you want to read. Be careful while specifying File path as path separator is different on Window and UNIX. Windows uses backslash while UNIX uses forward slash as a path separator.

How to read file in Java using Scanner Example - text files

Reading a file with Scanner

From Java 5 onwards java.util.Scanner class can be used to read file in Java. Earlier we have seen examples of reading file in Java using FileInputStream and reading file line by line using BufferedInputStream and in this Java tutorial, we will See How can we use Scanner to read files in Java. Scanner is a utility class in java.util package and provides several convenient methods to read int, long, String, double etc from a source which can be an InputStream, a file, or a String itself.

Top 43 Java IO and File System Interview Questions with Answers for 1 to 3 Years Experienced

Good knowledge of Java IO API is important for any Java developer but many of them barely pay attention to Java IO and NIO API, and that's why they often struggle during Java interviews when a question related to Input-Output operation is asked. In the past, I have shared many Java interview questions on topics like Collections, Concurrency, JVM internals, Garbage Collection, OOP, Design Patterns, and Data structure based coding problems, which received good feedback and helped many Java developer on their Java Interview preparation. Consequently, many of my readers were also asking about Java IO and File-based interview questions and this was one of the pending items on my TODO list for quite some time.

How to work with Files and Directories in Java? Example Tutorial

The File API is one of the important parts of any programming language or API and even though Java's file API both new and old, is powerful, they are not intuitive enough compared to other languages like Python. Apart from knowing the essential classes and abstractions e.g. File, InputStream, OutputStream, Reader, Writer, Channel, etc, you also need to know and remember some nitty-gritty detail to avoid subtle issues. There are many articles out there on the internet which can teach you how to read and write data from the file but there are very few which will tell you to do it in the right way.

How to lock a File before writing in Java? Example

A file is one of the oldest ways to store data and share data but if you are working in a shared file i.e a file that can be read or write by multiple readers and writers, you need to make sure that the file is locked before you try to write on it. This is needed to ensure that someone doesn't overwrite the data you are writing. Fortunately, Java provides a mechanism to lock a file before writing using the FileLock interface. You can get the handle of FileLock by using FileChannel for writing to a file. The FileChannel class is generally used to write faster in a large file and one of the common ways to write binary data in Java.

How to create a ZIP File in Java? ZipEntry and ZipOutputStream Compression Example

Since compressing and archiving old log files is an essential housekeeping job in any Java application environment, a Java programmer should know how to compress files in .zip format and then how to read them programmatically if required. The JDK provides full support to create and read ZIP files in Java. There is a separate package java.util.zip to hold all classes related to zipping and unzipping files and streams. In this series of articles, you will learn how to use those classes like ZipFile, ZipEntry, ZipInputStream, and ZipOutputStream, etc.

How to read a text file into ArrayList in Java? Examples

Prior to Java 7, reading a text file into an ArrayList involves a lot of boilerplate coding, as you need to read the file line by line and insert each line into an ArrayList, but from Java 7 onward, you can use the utility method Files.readAllLines() to read all lines of a text file into a List. This method returns a List of String that contains all lines of files. Later you can convert this List to ArrayList, LinkedList, or whatever list you want to. Btw, this the fourth article in the series of reading a text file in Java.

3 ways to Copy a File From One Directory to Another in Java, Examples

Even though Java is considered one of the best feature-rich programming languages, until Java 7, It didn't have any method to copy a file from one directory to another directory. It did have the java.io.File class, which provides a method to check if a file exists or not and methods for several other file operations but it lacks support for copying files from one folder to another. It was easy to write your own routine to copy a file using FileInputStream or FileChannel, most developers prefer to use Apache Commons IO library; which is not a bad idea at all.

How to read a text file as String in Java? Example

There was no easy way to read a text file as String in Java until JDK 7, which released NIO 2. This API now provides a couple of utility methods that you can use to read the entire file as String e.g. Files.readAllBytes() returns a byte array of the entire text file. You can convert that byte array to String to have a whole text file as String inside your Java program. If you need all lines of files as a List of String e.g. into an ArrayList, you can use Files.readAllLines() method. This returns a List of String, where each String represents a single line of the file.

How to load data from CSV file in Java - Example

You can load data from a CSV file in a Java program by using BufferedReader class from the java.io package. You can read the file line by line and convert each line into an object representing that data. Actually, there are a couple of ways to read or parse CSV files in Java e.g. you can use a third-party library like Apache commons CSV or you can use Scanner class, but in this example, we will use the traditional way of loading CSV files using BufferedReader.

How to write to File in Java using BufferedWriter [Example]

You can use either OutputStream or Writer class in Java to write data to a file in Java. For example, you can use a combination of FileWriter and BufferedWriter to write text content into a text file in Java. If you want to write raw bytes consider using FileOutputStream class. Just remember that InputStream is used to read data and OutputStream is used to write data to file or socket. You can write anything to file e.g. String, integer, float values, etc. Java provides DataOutputStream to write different data types directly into a file like writeInt() to write integer values, writeFloat() to write floating-point values into a file, and writeUTF() to write String into File. BufferedWriter, like its counterpart BufferedReader, allows you to perform buffered IO, which can drastically improve performance while reading large files.

How to append text to existing File in Java? Example

In the last tutorial, you have learned how to write data to a file in Java, and in this tutorial, you will learn how to append text to a file in Java. What is the difference between simply writing to a file vs appending data to a file? In the case of writing to a file, a program can start writing from the start but in the case of appending text, you start writing from the end of the file. You can append text into an existing file in Java by opening a file using FileWriter class in append mode. You can do this by using a special constructor provided by FileWriter class, which accepts a file and a boolean, which if passed as true then open the file in append mode.

Difference between FileReader vs FileInputStream in Java? Answer

Even though both FileReader and FileInputStream are used to read data from a file in Java, they are quite different. The main difference between the FileReader and FileInputStream is that one reads data from a character stream while the other reads data from a byte stream. The FileReader automatically converts the raw bytes into characters by using the platform's default character encoding. This means you should use this class if you are reading from a text file that has the same character encoding as the default one.

3 Examples to Read FileInputStream as String in Java - JDK7, Guava and Apache Commons

Java programming language provides streams to read data from a file, a socket and from other sources e.g. byte array, but developers often find themselves puzzled with several issues e.g. how to open connection to read data, how to close connection after reading or writing into file, how to handle IOException e.g. FileNotFoundException, EOFFileException etc. They are not confident enough to say that this code will work perfectly. Well, not everyone expect you to make that comment, but having some basics covered always helps. For example In Java, we read data from file or socket using InputStream and write data using OutputStream. Inside Java program, we often use String object to store and pass file data, that's why we need a way to convert InputStream to String in Java. As a Java developer, just keep two things in mind while reading InputStream data as String :

Java FileReader + BufferedReader Example

There are multiple ways to read a file in Java e.g. you can use a Scanner as we have seen in the last example, or you can use the BufferedReader class. The advantage of using a BufferedReader to read a text file is speed. It allows faster reading because of internal buffering provided by BufferedReader. Other Reader classes like FileReader access the file or disk every time you call the read() method but BufferedReader keeps 8KB worth of data in its internal buffer which you can read it without accessing the file multiple times. It's loaded when you access the file the first time for a subsequent read.

10 Examples of print(), println() and prinf() methods In Java - PrintStream

Hello guys, if you are working in Java or just started with Java then you have must come across statements like System.out.println("Hello world") to print something on console or command prompt. This is actually the first statement I wrote in Java when I started programming and at that time I didn't realize how it work and what is System and PrintStream class and what is out here but now I know and I am going to explain all this to you in this article, along with PrintStream class and its various print methods like print(), println() and particularly printf() to print various objects in Java. But, Before we get to the 10 examples of Printstream printf() in Java, let me tell you a little bit more about what exactly Printstream is.

How to Create File and Directory in Java with Example

Many beginners confused with the fact that the same class java.io.File is used to create both file and directories in Java. I agree, this is not very intuitive and junior developers probably start looking for a class called java.io.Directory, which doesn't exist. On the other hand, creating file and directories are simple in Java, as java.io.File provides methods like createNewFile() and mkdir() to create new file and directory in Java. These methods returns boolean, which is the result of that operation i.e. createNewFile() returns true if it successfully created file and mkdir() returns true if the directory is created successfully.

2 Ways to Read a Text File in Java? BufferredReader and Scanner Examples

You can read a text file in Java by using either Files, BufferedReader or Scanner class. Both classes provide convenient methods to read a text file line by line e.g. Scanner provides nextLine() method and BufferedReader provides readLine() method. If you are reading a binary file, you can use FileInputStream. By the way, when you are reading text data, you also need to provide character encoding, if you don't then the platform's default character encoding is used. In Java IO, streams like InputStream are used to read bytes, and Readers like FileReader are used to read character data.

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