Simple interest program in Java

In this post, we will learn how to calculate Simple Interest(S.I.) using the Java programming language.

Simple Interest is a quick and easy method of calculating the interest amount for a particular principal amount of money at some rate of interest. So, simple interest is the simplest and easiest way to determine how much extra you'll have to pay for your loan. For example, when a person takes a loan of Rs. 6000, at a rate of 10 p.a. for three years, the person's interest for three years will be simple interest on the borrowed money.

Simple Interest Formula

The Simple Interest(S.I.) formula is given by-

SI = (P x T x R)/100

Where,
P is the principle amount
T is the time and
R is the rate

Algorithm of Simple Interest

1. Declare Principal, Interest and Time of loans.
2. Calculate the Simple Interest by applying the formula.
3. Print the value of Simple Interest.

Java program to calculate Simple Interest

In the given Java program, we have defined the value of principal, rate, and time. We then use the formula for simple interest to compute the simple interest.

public class SimpleInterest 
{  
    public static void main (String args[])
    {   
        // define principal amount, rate, time and simple interest respectively 
        float principle, rate,  time,  si;  
        principle = 15000;  
        rate = 8; 
        time = 4;  
        si  = (principle*rate*time)/100;   
        System.out.println("Simple Interest is: " +si);  
    }
}

Simple Interest is: 4800.0

Java program to calculate Simple Interest using function

Here is a simple Java program to calculate simple interest using a user-defined function. We define a function simpleInterest() to calculate the simple interest using the formula. Next, within the main function, we declare the variables for the principal amount, rate of interest, and time period, and, then call the user-defined function and print the result.

public class SimpleInterest 
{  
    //User-defined program to find the simple interest
    public static float simpleInterest(float principal, float rate, float time)
    {
        float interest = (principal*rate*time)/100;
        return interest;
    }
    public static void main (String args[])
    {   
        //Declare variables
        float p, r, t;
        p = 23000;
        r = 5;
        t = 6;
        
        float si = simpleInterest(p,r,t);
        System.out.println("Simple interest is : " + si);
        
        //Declare variables
        float p1, r1, t1;
        p1 = 16000;
        r1 = 6;
        t1 = 8;
        
        float si1 = simpleInterest(p1,r1,t1);
        System.out.println("Simple interest is : " + si1);
    }
}

Simple interest is : 6900.0
Simple interest is : 7680.0

Simple interest program in Java using Scanner

In the given Java program, we create an instance of the Scanner class to take the input from the user. Next, we declare variables for the principal amount, rate of interest, and time period and ask the user to provide inputs for these variables. Then, we call the user-defined method to calculate the simple interest and print the result.

import java.util.Scanner;
public class SIMain
{
    //User-defined program to find the simple interest
    public static float simpleInterest(float principal, float rate, float time)
    {
        float interest = (principal*rate*time)/100;
        return interest;
    }

    public static void main(String args[]) 
    {
        //Taking input from the user
        //Creating an instance of Scanner class
        Scanner sc = new Scanner(System.in);
        
        //Declaring variables
        float p, r, t;
        System.out.println("Enter the principal: ");
        p = sc.nextFloat();    
        System.out.println("Enter the rate of interest: ");
        r = sc.nextFloat();    
        System.out.println("Enter the time period: ");
        t = sc.nextFloat();   
        sc.close();
        
        //Calling method to calculate the simple interest
        float si = simpleInterest(p,r,t);
        System.out.println("Simple interest is : " + si);

    }
    
}

Enter the principal: 25050
Enter the rate of interest: 7.3
Enter the time period: 10
Simple interest is : 18286.5

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