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User Input in Java

In this chapter, you'll learn how to interact with your Java programs by taking user input. This allows your programs to be flexible and respond based on what the user provides.

Here's the basic syntax :

user_input =Scanner.nextLine()

This code displays the prompt "Enter your name: " on the screen. The user types their name and presses Enter. The program then stores the entered name in the variable user_input.

Examples of User Input:

1. Greeting the User:

System.out.println("Enter yours name:");

string name=sc.nextLine()
System.out.println("Hello, "+ name +"!");

This program asks the user for their name and then prints a personalized greeting.

2. Getting Numbers from the User:
age =sc.nextInt()
System.out.println("You are"+age+"old");

Here, the program asks for the user's age. However, input() always returns a string. We use int() to convert the entered string to an integer before storing it in the age variable.

Examples: Basic Problems & Solutions

Example-1Write a program to accept the marks of student in Physics, Chemistry and Biology. Display the total marks and average marks.

Java code

													
													
import java.util.*;
class Student
{
    public static void main(String args[])
    {
       Scanner sc= new Scanner(System.in);
       int p,c,b,total;
       double avg;
       System.out.println("Enter the marks of student");
       System.out.println("Physics Marks-");
       p=sc.nextInt();
       System.out.println("Chemistry Marks-");
       c=sc.nextInt();
       System.out.println("Biology Marks-");
       b=sc.nextInt();
       total=p+c+b;
       avg=total/3;
       System.out.println("Total Marks="+total);
       System.out.println("Average Marks="+avg);
    }
}
													

												

OUTPUT:

Enter the marks of student
Physics Marks-
60
Chemistry Marks-
70
Biology Marks-
95
Total Marks=225
Average Marks=75.0

Example-2Write a program to accept the number of days and display the result after converting into number of years, number of months and the remaining number of days.

Java code

													
													
import java.util.*;
class days
{
   public static void main(String args[])
   {
      Scanner sc= new Scanner(System.in);
       int n,y,r,m,d;
       System.out.println("Enter the no of days:");
       n=sc.nextInt();
       y=n/365;
       r=n%365;
       m=r/30;
       d=r%30;
       System.out.println("Years "+y+" Months "+m+" Days "+d);
        
    }
}
													
												

OUTPUT:

Enter the no of days:
366
Years 1 Months 0 Days 1

Key Points to Remember:

input() always returns a string, even if the user enters a number.

You might need to convert the user input to a different data type (like integer or float) using functions like int(), float(), etc., depending on how you plan to use it in your program.

You can provide informative prompts within the input() function to guide the user on what kind of input is expected.

Practice Exercises:

1. Write a program that asks the user for their favorite color and then prints a message like "Your favorite color is blue!".

2. Write a program that asks the user for two numbers and then prints their sum.

Introduction User Input If-Else Loops For loop While Loop Do While Loop String Functions Arrays 2D Arrays Function Function Overloading
Method Overriding Date Time Function Collection Switch Case Class Constructor Inheritance Interface Encapsulation