Introduction

Taking user input in Java is the first step towards creating successful software in Java. The Java program collects input from the user through various input sources such as a mouse, keyboard, network request, CLI arguments, etc. Java also has various I/O packages that can be imported into the program to perform input-output operations. These packages support input of primitive types like double, integer, strings, etc.

This article will focus on methods like Scanner, BufferedReader, and InputStreamReader to take user input in Java.

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How to Take Input in Java using the Scanner Class?

The Scanner class is one of the methods in the “java.util” package that parses and handles all the primitive type inputs. The Scanner class asks the user to enter the input, and then it prints the same on the screen or console. You can import the Scanner class from the “java.util” package in the program and create an object to use its methods.

For example,

Scanner test = new Scanner(System.in);

In the above statement, the test is the name of an object, and System.in is the input stream. The Scanner instance created will scan the user input in Java.

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Note: It is not necessary to write System.in as the input string in your program. You can replace it with a file and a file to read, string as the input stream.

For example,

Scanner test = new Scanner(new FileInputStream(“testFile.txt”), “UTF-8”);

Make sure that you write code {test.close()} to close the scanner when you are done editing it.

Scanner Methods for Reading Inputs from User

The following table lists the methods that the scanner uses to read the input in Java entered by the user.

 Example

The following Java program uses the Scanner class to take user input in Java (string, integer, and afloat).

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Output

If you want to learn more about taking input in Java using the scanner class, check out the Multiple String Input in Java using the Scanner blog.

BufferedReader and InputStreamReader Methods

BufferedReader is another class in Java that scans the stream of characters from a character-based input stream. InputStreamReader is a function in Java that converts the input stream into a sequence of characters for BufferedReader to scan. The BufferedReader class accepts the InputStream as a parameter.

The BufferedReader class uses read() and readLine() methods to read characters and the next line and returns them.

You must import the java.io.BufferedReader package to create a BufferedReader class.  

// Creates a FileReader

FileReader test = new FileReader(String file);

// Creates a BufferedReader

BufferedReader a = new BufferedReader(test);

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BufferedReader Methods for Reading Inputs from User

The following table lists the methods that the buffered reader uses to read the input in Java entered by the user.

Example

The following Java program uses a BufferedReader class alongside an InputStreamReader class to take the user input in Java.

Output

In the above example, we created a buffered reader named buffer. The buffered reader is linked with the “user_input.txt” file.

Then, we used the readLine() method to scan the characters from the buffer of the buffered reader.

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Conclusion

In this article, we have covered the methods used to take user input in Java. We have discussed the Scanner and BufferedReader methods, along with examples. We have also discussed the methods that Scanner and BufferedReader class uses to take input in Java. We hope that you have got a basic understanding of how to handle input in Java. If you want to learn more Java programming language, check out upGrad’s Executive PG Program in Full Stack Development course designed for working professionals.