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One input doesn't work, while the rest does

The user must input the total purchase amount and how old they are, and then calculate the final payment.
If the total amount is $100 or over, there is a 20% discount off the total price. If the age is 65 or older, there is a 10% discount off the total price.
double discount1 = 0.10;
double discount2 = 0.20;
double totalPrice = 0.0;
double finalPrice = 0.0;
System.out.print("Enter total amount: ");
double purchase = input.nextDouble();
System.out.print("Enter age: ");
int age = input.nextInt();
if (purchase >= 100) {
totalPrice = purchase * discount2;
finalPrice = purchase - totalPrice;
System.out.print("The final amount is $" + finalPrice);
}
else if (purchase < 100 && age < 65) {
System.out.println("The final amount is $" + purchase);
}
else if (age >= 65) {
totalPrice = purchase * discount1;
finalPrice = purchase - totalPrice;
System.out.print("The final amount is $" + finalPrice);
}
The user would input 200 as the total amount and 75 as the age. The output is supposed to be $140.00. However, I receive the output as $160.00.

The first if statement will be executed first. Because the price is above 100. So the other statements will not be executed. Try to change the if expressions because of thats the problem why it's not giving the result you may expect

My approach would be to add all of the discounts together and then multiply once at the end.
Than you can add other discounts if needed
double totalDiscount = 0.0;
if (purchase >= 100) {
totalDiscount += discount2;
}
if (age >= 65) {
totalDiscount += discount1;
}
totalPrice = purchase * (1.0 - totalDiscount);
System.out.print("The final amount is $" + totalPrice);

You nee to change below code,
because when ever price is more then 100 it will run first if block and wont enter into last block.
so change it in below manner :-
if (purchase >= 100 && age < 65) {
totalPrice = purchase * discount2;
finalPrice = purchase - totalPrice;
System.out.print("The final amount is $" + finalPrice);
}
else if (purchase < 100 && age < 65) {
System.out.println("The final amount is $" + purchase);
}
else if (purchase < 100 &&age >= 65) {
totalPrice = purchase * discount1;
finalPrice = purchase - totalPrice;
System.out.print("The final amount is $" + finalPrice);
}
else if (age >= 65) {
totalPrice1 = purchase * discount2;
totalPrice = purchase * discount1;
finalPrice = purchase - totalPrice - totalPrice1 ;
System.out.print("The final amount is $" + finalPrice);
}

The program doesn't reassign the value in my if else statment

I am very new to Java and my assignment was to make a tax calculator. Everything seems to be working fine but when I print at the end it always prints 0 for federaltaxes. I make the double at the start and then try to reassign it depending on the situation through the else if statement.
//2353161 Tomas Pospisil
import java.util.Scanner;
public class PaymentCalculator {
public static void main(String[] args){
//Create Scanner for user input
Scanner input = new Scanner(System.in);
//Ask the user for Gross Pay
System.out.print("Please Enter Gross Pay: ");
double GrossPay = input.nextInt();
//Establish the integer for Number of Exemptions
int NoE = 0;
//Establish the integer for the value of exemption
double exemptionvalue = 0;
double federaltaxes = 0;
//Ask the user if they are married
System.out.print("Are you married: ");
String marriedstatus = input.next();
//If yes make the number of Exemptions equal the user input
if (marriedstatus.equals("yes")) {
System.out.print("Please enter Number of Exemptions: ");
NoE = input.nextInt();
}
//If not make the number of exemptions equal 1
else if(marriedstatus.equals("no")) {
NoE = 1;
}
//If NoE is greater than 4 make it 5 for later use
if (NoE >4) {
NoE = 5;
}
// Depending on the number of exemptions the program assigns it a value for later use
switch (NoE) {
case 1:
exemptionvalue = 1000;
break;
case 2:
exemptionvalue = 1800;
break;
case 3:
exemptionvalue = 2400;
break;
case 4:
exemptionvalue = 3600;
break;
case (5):
exemptionvalue = 4000;
break;
}
//Calculate adjusted wages
double adjustedwages = GrossPay - exemptionvalue;
// Figure out the tax percentage
if (GrossPay >= 10000) {
federaltaxes = GrossPay * 0;
}
else if (GrossPay <= 30000 && GrossPay >= 10000) {
federaltaxes = GrossPay * 0.15 ;
}
else if (GrossPay > 30000) {
federaltaxes = GrossPay * 0.20 ;
}
//Program calculates the FICA
double FICA = (GrossPay * .065);
//Program calculates Medicare
double Medicare = (GrossPay * .014);
//Program calculates the federal taxes
//Program Calculates Net Pay
double NetPay = GrossPay - (FICA + Medicare + federaltaxes);
//Program prints the results
System.out.println(" Payroll Taxes");
System.out.println("Gross.....$ " + GrossPay);
System.out.println("Exemptions: " + NoE);
System.out.println("Federal Taxes.....$ " + federaltaxes);
System.out.println(" FICA.....$ " + FICA);
System.out.println(" Medicare.....$ " + Medicare);
System.out.println("-----------------------------");
System.out.println("Net Pay.....$ " + NetPay);
}
}

This is the block that is causing you trouble.
if (GrossPay >= 10000) {
federaltaxes = GrossPay * 0;
}
Any GrossPay amount above 10000 is going to pass the condition and be multiplied by 0.

You have a wrong condition in the if where you evaluate federal taxes, it should be:
if (GrossPay < 10000) {
federaltaxes = GrossPay * 0;
}
else if (GrossPay <= 30000 && GrossPay >= 10000) {
federaltaxes = GrossPay * 0.15 ;
}
else if (GrossPay > 30000) {
federaltaxes = GrossPay * 0.20 ;
}
your code will never evaluate the else condition

It is because your condition logic is wrong
double federaltaxes = 0;
// Figure out the tax percentage
if (GrossPay >= 10000) {
federaltaxes = GrossPay * 0;
} else if (GrossPay <= 30000 && GrossPay >= 10000) {
federaltaxes = GrossPay * 0.15;
} else if (GrossPay > 30000) {
federaltaxes = GrossPay * 0.20;
}
Your first condition will always be true if the Grosspay is >= 10000 so federaltaxes here is 0, then the rest of your if else will not be evaluated because your first condition will always evaluate first. Also you dont have a separate else statement for the rest of the scenarios

Calculate total amount

When try to run I got wrong answer. What's wrong in my program?
Got answer is only for discount_amount not able to get total amount.
Scanner input = new Scanner(System.in);
double dicount_amount = 0;
double discount1 = 0;
double total = 0;
System.out.println("Enter the cost of the software: ");
double cost = input.nextDouble();
System.out.println(" Enter the quantity sold: ");
int quantity = input.nextInt();
if (cost > 0 && quantity > 0){
if(quantity >= 10 && quantity >=19){
discount1 = 20/100;
}
else if(quantity >= 20 && quantity >=49){
discount1 = 30/100;
}
else if(quantity >= 50 && quantity >=99){
discount1 = 40/100;
}
else if(quantity <=100){
discount1 = 50/100;
}
}
else {
System.out.println( " please enter valid input ");
}
double total1 = cost * quantity;
dicount_amount = total1 * discount1;
total= total1 - dicount_amount;
System.out.println("Total Cost: " + total);
}

Simplest thing you can do is not to divide discount1 = 20/100;, instead that you can set directly value discount1 = 0.2;
Also you should check your if statement
Example:
if(quantity >= 10 && quantity >=19)
is equal to
if(quantity >=19)
I think you want to check if quantity is between. So you should use
if(quantity >= 10 && quantity <=19)

Guess what was your mistake? You were dividing int by int and you are excepting a double result. Typecast the division to double or do 20.0/100. Also, I assume you are want to give a discount if the quantity is between 10 and 19. What you have been doing doesn't make sense because every time you run your program it will never fall in else if() statement because you are setting quantity>=19 in if statement.
here are few changes I made in your code :
Scanner input = new Scanner(System.in);
double dicount_amount = 0;
double discount1 = 0;
double total = 0;
System.out.println("Enter the cost of the software: ");
double cost = input.nextDouble();
System.out.println(" Enter the quantity sold: ");
int quantity = input.nextInt();
if (cost > 0 && quantity > 0){
if(quantity >= 10 && quantity <=19){
discount1 = (double)20/100;
}
else if(quantity >= 20 && quantity <=49){
discount1 = (double)30.0/100;
}
else if(quantity >= 50 && quantity <=99){
discount1 = (double)40.0/100;
}
else if(quantity >=100){
discount1 = (double)50.0/100;
}
}
else {
System.out.println( " please enter valid input ");
}
double total1 = cost * quantity;
dicount_amount = total1 * discount1;
total= total1 - dicount_amount;
System.out.println("Total Cost: " + total);
Output :
Enter the cost of the software:15
Enter the quantity sold:16
Total Cost: 192.0

Calculating change from 2 inputs by a user

i am trying to output the minimum amount of notes needed from two inputs. one being the cost and the other being the amount handed over by the customer.
so if i enter 400 and then 500, it should say 2 $50 dollars notes.
or if i enter 60 and then 80, it should say 1 $20 dollar note.
this is a small bit of my code:
import java.util.Scanner;
public class bank {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter amount due: ");
int amount = input.nextInt();
System.out.println("Amount tendered: ");
int tmp = input.nextInt();
int change;
if(amount >= 50)
{
change =(tmp - amount)/50;
System.out.println (change + " $50 bills");
}
if(amount >= 20)
{
change =(tmp - amount)/20;
System.out.println (change + " $20 bills");
}

You can achieve it by using mod operator %
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Enter amount due: ");
int amount = input.nextInt();
System.out.println("Amount tendered: ");
int tmp = input.nextInt();
int change;
int diff = tmp - amount;
if (diff % 50 == 0) {
change = diff / 50;
System.out.println(change + " $50 bills");
}
else if (diff % 20 == 0) {
change = diff / 20;
System.out.println(change + " $20 bills");
}
}

Once you calculate the amount of change in a value of a bill, you need to lower the amount of change required. This is done in the code changeRequired = changeRequired - change;
System.out.println("Amount tendered: ");
int tmp = input.nextInt();
int changeRequired = tmp - amount;
int change;
if(amount >= 50)
{
change =(changeRequired)/50;
changeRequired = changeRequired - change;
System.out.println (change + " $50 bills");
}
if(amount >= 20)
{
change =(changeRequired )/20;
changeRequired = changeRequired - change;
System.out.println (change + " $20 bills");
}

Once you get your change which is the variable amount, you can use the following code to find out how many notes of each of the $50, $20, $10, $5, $1 there are in the change. The number of notes is minimal.
numOf50 = 0; // number of $50 dollar bills, the rest is similar.
numOf20 = 0; // ...
numOf10 = 0; // ...
numOf5 = 0;
numOf1 = 0;
if (amount / 50 > 1){
numOf50 += (amount / 50);
amount %= 50; // update the amount with the remainder
}
else if (amount / 20 > 1){
numOf20 += (amount /20);
amount %= 20;
}
else if (amount / 10 > 1){
numOf10 += (amount / 10);
amount %= 10;
}
else if (amount / 5 > 1){
numOf5 += (amount / 5);
amount %= 5;
}
else if (amount <=5 && amount >0){
numOf1 = amount;
}
// output is trivial, omitted.
Haven't tested on a machine but it should work or give you an idea.

Print data from another method, in a while loop in the main method only once

The goal of this assignment is to read two numbers from the user, compute the distance between those numbers, then continue to ask the user for two numbers until they are equal, each time competing the distance, and the goal is to find the minimum distance between two numbers. We have to create a method that finds the minimum distance, and once the two numbers are equal, to print that minimum distance (only once). And the distance between the numbers that are equal does not count as a minimum distance. How do I do this? Thank you.
This is the code that I currently have.
double myMin = Double.MAX_VALUE;
while ( !(num1==num2)) {
double dist;
pairsMin(dist,myMin,num1,num2);
// re-ask for user input of num1 and num2
Min1 = pairsMin(dist,myMin,num1,num2);
}
System.out.print("\nThe minimum distance is: " + Min1 + "\n");
} // end of main method
public static double pairsMin( double dist, double myMin, double num1,double num2){
dist = Math.abs(num1-num2);
if ( dist<myMin) { // if dist is smaller than the minimum, then dist will be the new minimum
myMin = dist;
}
return myMin;
} // end of pairsMin method

You have to make minor changes to your logic. Try below
public static int pairsMin(int min, int num1, int num2) {
int dist = 0;
dist = Math.abs(num1 - num2);
if (dist != 0 && dist < min) {
min = dist;
}
return min;
}
public static void main(String[] args) {
Scanner kb = new Scanner(System.in);
int num1;
int num2;
int mymin = Integer.MAX_VALUE;
do {
System.out.print("Enter number 1: ");
num1 = kb.nextInt();
System.out.print("Enter number 2: ");
num2 = kb.nextInt();
mymin = pairsMin(mymin, num1, num2);
} while (!(num1 == num2));
System.out.print("\nThe minimum distance is: " + mymin + "\n");
} // end of main method

This is what I know have, using your suggestions, and it is working. I didn't think that my if statement in my while loop would execute because I thought once num1==num2, that the while loop would end, but it worked. Thank you!
import java.util.Scanner;
public class hw5_pairs {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.print("Enter number 1: ");
double num1 = in.nextDouble();
System.out.print("Enter number 2: ");
double num2 = in.nextDouble();
double Min1;
double myMin = Double.MAX_VALUE;
double dist = Math.abs(num1-num2);
while ( !(num1==num2)) {
pairsMin(dist, num1, num2, myMin);
System.out.print("Enter number 1: ");
num1 = in.nextDouble();
System.out.print("Enter number 2: ");
num2 = in.nextDouble();
Min1 = pairsMin(dist,num1, num2, myMin);
if (num1==num2) {
System.out.print("\nThe minimum distance is: " + Min1 + "\n");
}
}
}
public static double pairsMin( double dist, double num1, double num2, double myMin){
if ( dist<myMin) { // if dist is smaller than the minimum, then dist will be the new minimum
myMin = dist;
}
return myMin;
}
}

My new problem is that myMin is equalling the last distance before the numbers are equal instead of the actual minimum. e.g. say the first two numbers I enter are 1 and 2, and the next are 1 and 3, and then 1 and 1. It is saying my minimum is 2.0.
This is what I'm supposed to get for the assignment.
Enter number 1: 9
Enter number 2: 1
Enter number 1: 7
Enter number 2: 2
Enter number 1: 4
Enter number 2: 4
The minimum distance is: 5.0.
Enter number 1: 20
Enter number 2: 3
Enter number 1: 23
Enter number 2: 23
5.0 + 17.0 = 22.0
MY CODE:
double myMin = Double.MAX_VALUE;
double Min1,Min2;
while ( !(num1==num2) ) {
pairsMin( num1, num2, myMin);
Min1 = pairsMin( num1, num2, myMin);
System.out.print("Enter number 1: ");
num1 = in.nextDouble();
System.out.print("Enter number 2: ");
num2 = in.nextDouble();
if (num1==num2) {
System.out.print("\nThe minimum distance is: " + Min1 + "\n\n");
myMin = Double.MAX_VALUE;
System.out.print("Enter number 1: ");
num1 = in.nextDouble();
System.out.print("Enter number 2: ");
num2 = in.nextDouble();
while ( !(num1==num2)) {
pairsMin( num1, num2, myMin);
Min2 = pairsMin(num1,num2,myMin);
System.out.print("Enter number 1: ");
num1 = in.nextDouble();
System.out.print("Enter number 2: ");
num2 = in.nextDouble();
if(num1==num2) {
double totMin = Min1+Min2;
System.out.print("\n" + Min1 + " + " + Min2 + " = " + totMin + "\n");
}
}
}
} // end while loop
} // end main method
public static double pairsMin( double num1, double num2, double myMin){
double dist = Math.abs(num1-num2);
if ( dist<myMin) { // if dist is smaller than the minimum, then dist will be the new minimum
myMin = dist;
}
return myMin;
}
}