In this Java article we want to learn about Input and Output Operations in Java, Java is popular programming language that provides support for input and output operations. these operations allow you to interact with external resources such as files, networks and user input. in this article we want to talk about input and output operations in Java.
Input Operations
Input operations are used to receive data from an external source into the program. Java provides several classes and methods to read data from different sources, such as keyboard or a file.
Keyboard Input
Scanner class is commonly used to read input from the keyboard. this is an example of how to use the Scanner class to read user input, in this code snippet, we have created Scanner object that reads from standard input stream (System.in). after that we prompted the user to enter their name and read their input using the nextLine() method.
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import java.util.List; import java.util.Scanner; public class HelloWorld { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("Enter your name: "); String name = scanner.nextLine(); System.out.println("Your name is : " + name); } } |
This will be the result
File Input
Java provides several classes to read data from files, such as FileInputStream and FileReader. this is an example of how to use the FileReader class to read a file:
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import java.io.FileReader; import java.io.IOException; public class HelloWorld { public static void main(String[] args) { try (FileReader reader = new FileReader("example.txt")) { int character; while ((character = reader.read()) != -1) { System.out.print((char) character); } } catch (IOException e) { e.printStackTrace(); } } } |
In the above code we have used FileReader class to open file example.txt. after that we read the file character by character using read() method and print each character to the console.
This will be the result
Output Operations
Output operations are used to send data from the program to an external destination. Java provides several classes and methods to write data to different destinations, such as console or a file.
Console Output
System.out object is commonly used to write output to the console. this is an example of how to use System.out object to write output:
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System.out.println("Hello geekscoders.com"); |
File Output
Java provides several classes to write data to files, such as FileOutputStream and FileWriter. this is an example of how to use the FileWriter class to write to a file:
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import java.io.FileWriter; import java.io.IOException; public class HelloWorld { public static void main(String[] args) { try (FileWriter writer = new FileWriter("example.txt")) { writer.write("Text is changed from example.txt"); } catch (IOException e) { e.printStackTrace(); } } } |
In the above code we have used FileWriter class to open the file example.txt. after that we have used write() method to write a string to the file.