Quick Answer: How To Use Scanner To Read A File In Java?

Can a scanner read a file Java?

Reading file with Scanner Scanner class can be used to read file in Java.

How do you create a scanner to read data from a file in Java?

Example- File Object

  1. Create a File object representing your required file.
  2. Create a Scanner class by passing the above created file object.
  3. The hasNext() verifies whether the file has another line and the nextLine() method reads and returns the next line in the file. Using these methods read the contents of the file.

How do I read a Java file?

There are several ways to read a plain text file in Java e.g. you can use FileReader, BufferedReader or Scanner to read a text file. Every utility provides something special e.g. BufferedReader provides buffering of data for fast reading, and Scanner provides parsing ability.

What is the best way to read file in Java?

If you want to read a file line by line, using BufferedReader is a good choice. BufferedReader is efficient in reading large files. The readline() method returns null when the end of the file is reached.

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How do you read a file in Linux?

Following are some useful ways to open a file from the terminal:

  1. Open the file using cat command.
  2. Open the file using less command.
  3. Open the file using more command.
  4. Open the file using nl command.
  5. Open the file using gnome-open command.
  6. Open the file using head command.
  7. Open the file using tail command.

What is the difference between BufferReader and scanner?

Scanner and BufferReader both classes are used to read input from external system. Scanner is normally used when we know input is of type string or of primitive types and BufferReader is used to read text from character streams while buffering the characters for efficient reading of characters.

How do I read a file from FileInputStream?

Java FileInputStream example 1: read single character

  1. import java.io. FileInputStream;
  2. public class DataStreamExample {
  3. public static void main(String args[]){
  4. try{
  5. FileInputStream fin=new FileInputStream (“D:\testout.txt”);
  6. int i=fin. read ();
  7. System.out.print((char)i);
  8. fin.close();

How do you use delimiter?

Example 2

  1. import java.util.Scanner;
  2. public class ScannerDelimiterExample2 {
  3. public static void main(String args[]){
  4. //Create Scanner object.
  5. Scanner scan = new Scanner(“Hello World!” );
  6. //Printing the delimiter used.
  7. System.out.println(” Delimiter:”+scan. delimiter ());
  8. //Printing the tokenized Strings.

What is scanner in Java?

Scanner is a class in java. util package used for obtaining the input of the primitive types like int, double, etc. and strings. It is the easiest way to read input in a Java program, though not very efficient if you want an input method for scenarios where time is a constraint like in competitive programming.

How do I read properties file?

Test.java

  1. import java.util.*;
  2. import java.io.*;
  3. public class Test {
  4. public static void main(String[] args)throws Exception{
  5. FileReader reader=new FileReader(“db. properties “);
  6. Properties p=new Properties ();
  7. p. load (reader);
  8. System.out.println(p.getProperty(“user”));
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How do you read and print a string in Java?

Example of nextLine() method

  1. import java.util.*;
  2. class UserInputDemo1.
  3. {
  4. public static void main( String [] args)
  5. {
  6. Scanner sc= new Scanner(System.in); //System.in is a standard input stream.
  7. System.out. print (“Enter a string: “);
  8. String str= sc.nextLine(); //reads string.

How do you read a comma separated text file in Java?

Reading and Writing CSVs in Java

  1. Use FileReader to open the CSV file.
  2. Create a BufferedReader and read the file line by line until an “End of File ” (EOF) character is reached.
  3. Use the String. split() method to identify the comma delimiter and split the row into fields.

How do I read large files?

  1. Introduction. What’s the most efficient and easiest way to read a large file in java?
  2. Loading Whole File Into Memory. One way to load the whole file into a String is to use NIO.
  3. Loading a Binary File in Chunks.
  4. Reading a Text File Line By Line.
  5. Using a Scanner.
  6. With Java 8 Streams.

How do you split a string in Java?

Following are the two variants of split () method in Java:

  1. Public String [ ] split ( String regex, int limit )
  2. public String [] split ( String regex) This variant of split method takes a regular expression as parameter, and breaks the given string around matches of this regular expression regex. Here by default limit is 0.

How do I read a large file in Java?

How to Read Large File in Java

  1. 1 Using Java API. We will cover various options how to read a file in Java efficiently using plain Java API. 1.1 Using Java BufferReader.
  2. 2 Streaming File Using Apache Commons IO. This can also be achieved by using Apache Commons IO FileUtils.lineIterator () Method.

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