Java Input and Output Practice Questions with Solutions

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Input and Output (I/O) operations are among the most essential concepts in Java programming. Almost every Java application interacts with users by accepting input and displaying output. Whether you’re developing a console application, desktop software, Android app, or enterprise system, understanding Java input and output is a fundamental skill.

Java provides several ways to accept input from users. The most commonly used approach is the Scanner class, which is simple and beginner-friendly. Java also supports BufferedReader, which is faster and often preferred in competitive programming and performance-critical applications.

For displaying output, Java provides methods such as System.out.print(), System.out.println(), and System.out.printf() for formatted printing.

In this chapter, you’ll practice Java programs that cover different input and output techniques, helping you build confidence in reading user input, displaying results, and formatting output.

You’ll learn concepts including:

  • Scanner Class
  • BufferedReader
  • Reading Integer Input
  • Reading Floating-Point Numbers
  • Reading Strings
  • Reading Characters
  • Multiple User Inputs
  • Formatted Output using printf()

Each practice question includes a complete Java solution, sample input, sample output, explanation, and concepts covered, making it ideal for beginners, college students, placement preparation, and technical interviews. Java Input and Output practice questions with solutions help to understand the concepts.

1. Java Program to Read an Integer Using Scanner Class

Problem Statement

Write a Java program to accept an integer from the user using the Scanner class and display it.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        int number;

        System.out.print("Enter an Integer: ");
        number = scanner.nextInt();

        System.out.println("You Entered: " + number);

        scanner.close();

    }

}

Sample Input

Enter an Integer: 50

Sample Output

You Entered: 50

Explanation

The Scanner class reads an integer from the keyboard using the nextInt() method and stores it in an integer variable.

Concepts Covered

  • Scanner Class
  • Integer Input
  • Variables
  • User Input

2. Java Program to Read a Floating-Point Number

Problem Statement

Write a Java program to accept a decimal number from the user and display it.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        double number;

        System.out.print("Enter a Decimal Number: ");
        number = scanner.nextDouble();

        System.out.println("You Entered: " + number);

        scanner.close();

    }

}

Sample Input

Enter a Decimal Number: 45.75

Sample Output

You Entered: 45.75

Explanation

The nextDouble() method reads a floating-point value entered by the user.

Concepts Covered

  • Scanner Class
  • double Data Type
  • User Input

3. Java Program to Read a String Using Scanner

Problem Statement

Write a Java program to accept a single-word string from the user.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String name;

        System.out.print("Enter Your Name: ");
        name = scanner.next();

        System.out.println("Welcome " + name);

        scanner.close();

    }

}

Sample Input

Enter Your Name: Rishabh

Sample Output

Welcome Rishabh

Explanation

The next() method reads a single word from the user until a space is encountered.

Concepts Covered

  • Scanner Class
  • String Input
  • next() Method
  • User Input

4. Java Program to Read a Full Sentence Using nextLine()

Problem Statement

Write a Java program to accept a complete sentence from the user using the nextLine() method and display it.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String sentence;

        System.out.print("Enter a Sentence: ");
        sentence = scanner.nextLine();

        System.out.println("You Entered:");
        System.out.println(sentence);

        scanner.close();

    }

}

Sample Input

Enter a Sentence: Java is an object oriented programming language.

Sample Output

You Entered:
Java is an object oriented programming language.

Explanation

The nextLine() method reads the entire line entered by the user, including spaces, until the Enter key is pressed.

Difference Between next() and nextLine()

MethodReads
next()Only one word (stops at space)
nextLine()Complete line including spaces

Concepts Covered

  • Scanner Class
  • nextLine() Method
  • String Input
  • User Input

5. Java Program to Read a Character from the User

Problem Statement

Write a Java program to accept a character from the user and display it.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        char character;

        System.out.print("Enter a Character: ");

        character = scanner.next().charAt(0);

        System.out.println("Character Entered = " + character);

        scanner.close();

    }

}

Sample Input

Enter a Character: A

Sample Output

Character Entered = A

Explanation

The Scanner class does not provide a direct method to read a character.

Instead:

  • next() reads the first word.
  • charAt(0) extracts the first character of that word.

Example:

Input:

Coding

Output:

C

Concepts Covered

  • Scanner Class
  • Character Input
  • charAt() Method
  • String Handling

6. Java Program to Read Multiple Inputs Using Scanner

Problem Statement

Write a Java program to accept a student’s name, age, and percentage using the Scanner class and display the entered information.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String name;
        int age;
        double percentage;

        System.out.print("Enter Name: ");
        name = scanner.nextLine();

        System.out.print("Enter Age: ");
        age = scanner.nextInt();

        System.out.print("Enter Percentage: ");
        percentage = scanner.nextDouble();

        System.out.println("\nStudent Details");
        System.out.println("-----------------------");
        System.out.println("Name : " + name);
        System.out.println("Age : " + age);
        System.out.println("Percentage : " + percentage);

        scanner.close();

    }

}

Sample Input

Enter Name: Rishabh Kumar
Enter Age: 22
Enter Percentage: 88.5

Sample Output

Student Details
-----------------------
Name : Rishabh Kumar
Age : 22
Percentage : 88.5

Explanation

This program demonstrates how to read different types of user input in a single program using the Scanner class.

Concepts Covered

  • Scanner Class
  • Multiple User Inputs
  • String Input
  • Integer Input
  • Double Input

7. Java Program to Display Formatted Output Using printf()

Problem Statement

Write a Java program to display formatted output using the printf() method.

Java Solution

public class Main {

    public static void main(String[] args) {

        String name = "Rishabh";
        int age = 22;
        double percentage = 91.75;

        System.out.printf("Name : %s%n", name);
        System.out.printf("Age : %d%n", age);
        System.out.printf("Percentage : %.2f%n", percentage);

    }

}

Sample Output

Name : Rishabh
Age : 22
Percentage : 91.75

Explanation

The printf() method formats the output using format specifiers.

Common Format Specifiers

SpecifierDescription
%dInteger
%fFloating-point number
%.2fDecimal number with 2 digits after the decimal
%sString
%cCharacter
%nNew line

Concepts Covered

  • printf()
  • Formatted Output
  • Format Specifiers

8. Java Program to Read Data Using BufferedReader

Problem Statement

Write a Java program to accept a string using the BufferedReader class.

Java Solution

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {

    public static void main(String[] args) throws IOException {

        BufferedReader reader =
                new BufferedReader(
                        new InputStreamReader(System.in));

        System.out.print("Enter Your Name: ");

        String name = reader.readLine();

        System.out.println("Welcome " + name);

    }

}

Sample Input

Enter Your Name: Java Learner

Sample Output

Welcome Java Learner

Explanation

BufferedReader reads an entire line of text using the readLine() method. It is generally faster than Scanner for large input.

Concepts Covered

  • BufferedReader
  • InputStreamReader
  • readLine()
  • IOException

9. Java Program to Read an Integer Using BufferedReader

Problem Statement

Write a Java program to accept an integer using BufferedReader.

Java Solution

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {

    public static void main(String[] args) throws IOException {

        BufferedReader reader =
                new BufferedReader(
                        new InputStreamReader(System.in));

        System.out.print("Enter an Integer: ");

        int number = Integer.parseInt(reader.readLine());

        System.out.println("Number = " + number);

    }

}

Sample Input

Enter an Integer: 120

Sample Output

Number = 120

Explanation

Since readLine() always returns a String, the Integer.parseInt() method converts it into an integer.

Concepts Covered

  • BufferedReader
  • Integer.parseInt()
  • String to Integer Conversion

10. Java Program to Read a Double Using BufferedReader

Problem Statement

Write a Java program to accept a decimal number using BufferedReader.

Java Solution

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {

    public static void main(String[] args) throws IOException {

        BufferedReader reader =
                new BufferedReader(
                        new InputStreamReader(System.in));

        System.out.print("Enter Decimal Number: ");

        double number =
                Double.parseDouble(reader.readLine());

        System.out.println("Number = " + number);

    }

}

Sample Input

Enter Decimal Number: 99.75

Sample Output

Number = 99.75

Explanation

Double.parseDouble() converts the string returned by readLine() into a double value.

Concepts Covered

  • BufferedReader
  • Double.parseDouble()
  • String to Double Conversion
  • User Input

11. Java Program to Read Multiple Numbers Using BufferedReader

Problem Statement

Write a Java program to accept two integers using BufferedReader and display their sum.

Java Solution

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {

    public static void main(String[] args) throws IOException {

        BufferedReader reader =
                new BufferedReader(
                        new InputStreamReader(System.in));

        System.out.print("Enter First Number: ");
        int firstNumber = Integer.parseInt(reader.readLine());

        System.out.print("Enter Second Number: ");
        int secondNumber = Integer.parseInt(reader.readLine());

        int sum = firstNumber + secondNumber;

        System.out.println("Sum = " + sum);

    }

}

Sample Input

Enter First Number: 25
Enter Second Number: 35

Sample Output

Sum = 60

Explanation

The program accepts two integers using BufferedReader, converts them into integers using Integer.parseInt(), and calculates their sum.

Concepts Covered

  • BufferedReader
  • Integer.parseInt()
  • Arithmetic Operations
  • User Input

12. Java Program to Calculate the Sum Using Scanner Input

Problem Statement

Write a Java program to accept three numbers using the Scanner class and display their sum.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        int firstNumber, secondNumber, thirdNumber;

        System.out.print("Enter First Number: ");
        firstNumber = scanner.nextInt();

        System.out.print("Enter Second Number: ");
        secondNumber = scanner.nextInt();

        System.out.print("Enter Third Number: ");
        thirdNumber = scanner.nextInt();

        int sum = firstNumber + secondNumber + thirdNumber;

        System.out.println("Sum = " + sum);

        scanner.close();

    }

}

Sample Input

Enter First Number: 10
Enter Second Number: 20
Enter Third Number: 30

Sample Output

Sum = 60

Explanation

The Scanner class accepts multiple integer inputs and stores them in variables before calculating the total.

Concepts Covered

  • Scanner Class
  • Multiple Inputs
  • Variables
  • Arithmetic Operations

13. Java Program to Display User Details

Problem Statement

Write a Java program to accept and display user details such as name, age, city, and salary.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        String name;
        String city;
        int age;
        double salary;

        System.out.print("Enter Name: ");
        name = scanner.nextLine();

        System.out.print("Enter Age: ");
        age = scanner.nextInt();

        scanner.nextLine();

        System.out.print("Enter City: ");
        city = scanner.nextLine();

        System.out.print("Enter Salary: ");
        salary = scanner.nextDouble();

        System.out.println("\nEmployee Details");
        System.out.println("-----------------------");
        System.out.println("Name : " + name);
        System.out.println("Age : " + age);
        System.out.println("City : " + city);
        System.out.println("Salary : " + salary);

        scanner.close();

    }

}

Sample Input

Enter Name: Rahul Sharma
Enter Age: 25
Enter City: Delhi
Enter Salary: 45000

Sample Output

Employee Details
-----------------------
Name : Rahul Sharma
Age : 25
City : Delhi
Salary : 45000.0

Explanation

This program demonstrates reading multiple data types using a single Scanner object.

The extra scanner.nextLine() is used to consume the newline character left after reading the integer.

Concepts Covered

  • Scanner Class
  • Multiple Data Types
  • String Input
  • nextLine()

14. Java Program to Read Mixed Data Types

Problem Statement

Write a Java program to accept an integer, double, character, and string from the user.

Java Solution

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        int age;
        double marks;
        char grade;
        String name;

        System.out.print("Enter Age: ");
        age = scanner.nextInt();

        System.out.print("Enter Marks: ");
        marks = scanner.nextDouble();

        System.out.print("Enter Grade: ");
        grade = scanner.next().charAt(0);

        scanner.nextLine();

        System.out.print("Enter Name: ");
        name = scanner.nextLine();

        System.out.println("\nStudent Details");
        System.out.println("--------------------");
        System.out.println("Name : " + name);
        System.out.println("Age : " + age);
        System.out.println("Marks : " + marks);
        System.out.println("Grade : " + grade);

        scanner.close();

    }

}

Sample Input

Enter Age: 20
Enter Marks: 89.5
Enter Grade: A
Enter Name: Aman Gupta

Sample Output

Student Details
--------------------
Name : Aman Gupta
Age : 20
Marks : 89.5
Grade : A

Explanation

This program demonstrates how to read different data types in a single Java program.

Concepts Covered

  • Scanner Class
  • Mixed Data Types
  • Character Input
  • String Input

15. Java Program to Demonstrate print(), println(), and printf()

Problem Statement

Write a Java program to demonstrate the difference between print(), println(), and printf().

Java Solution

public class Main {

    public static void main(String[] args) {

        System.out.print("Java ");
        System.out.print("Programming");

        System.out.println();

        System.out.println("Input Output");

        System.out.printf("Percentage = %.2f", 92.567);

    }

}

Sample Output

Java Programming
Input Output
Percentage = 92.57

Explanation

print()

Displays text without moving to the next line.

println()

Displays text and moves the cursor to the next line.

printf()

Displays formatted output using format specifiers.

Concepts Covered

  • print()
  • println()
  • printf()
  • Formatted Output
  • Java Output Methods

Chapter Summary

In this chapter, you learned the fundamentals of Java Input and Output (I/O), one of the most important concepts in Java programming. You practiced accepting user input using the Scanner class and BufferedReader, displaying output using print(), println(), and printf(), and handling different data types such as integers, doubles, characters, strings, and mixed inputs.

You also learned how to format output, convert strings into numeric values using parsing methods, and read complete sentences from the user. These skills are essential for building interactive Java applications and are widely used in real-world software development.

Mastering Java Input and Output prepares you for advanced topics such as Conditional Statements, Loops, Methods, Object-Oriented Programming (OOP), File Handling, JDBC, and Spring Boot.

Key Takeaways

  • The Scanner class is the easiest way to accept user input in Java.
  • BufferedReader provides faster input for larger applications.
  • next(), nextLine(), nextInt(), and nextDouble() read different types of input.
  • print(), println(), and printf() display output in different formats.
  • printf() supports formatted output using format specifiers.
  • Parsing methods such as Integer.parseInt() convert strings into numeric values.
  • Handling mixed data types requires proper management of the input buffer.
  • Java Input and Output concepts are used in almost every Java application.
  • Understanding I/O improves programming logic and problem-solving skills.
  • Strong I/O knowledge is essential for coding interviews and real-world Java development.

Frequently Asked Questions (FAQs)

1. What is Input and Output in Java?

Input refers to accepting data from the user, while output refers to displaying information on the screen.

2. Which class is commonly used for user input in Java?

The Scanner class from the java.util package is the most commonly used class for reading user input.

Example:

Scanner scanner = new Scanner(System.in);

3. What is the difference between next() and nextLine()?

MethodDescription
next()Reads only one word until a space is encountered.
nextLine()Reads the entire line including spaces.

4. Why is BufferedReader faster than Scanner?

BufferedReader reads larger blocks of data at once, making it faster than Scanner for large input and competitive programming.

5. What is the purpose of printf()?

The printf() method displays formatted output using format specifiers.

Example:

System.out.printf("%.2f", 95.678);

Output:

95.68

6. Why do we use Integer.parseInt()?

BufferedReader.readLine() returns a string. Integer.parseInt() converts that string into an integer.

Example:

int number = Integer.parseInt(reader.readLine());

7. Why is scanner.nextLine() used after nextInt()?

After reading an integer, the newline character remains in the input buffer. Calling nextLine() consumes this leftover newline before reading the next string.

8. Why are Java Input and Output concepts important?

They allow Java applications to interact with users, process data, display results, and form the basis for almost every console, desktop, Android, and enterprise application.

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

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