I am having difficulties with finding all possible odd numbers for my program. I am required to use a while loop to find all the odd numbers but i am not sure how to print it out. I dont know if im doing anything wrong in this block while((num1+num2)%2==0) because that was just a guess. Outline of the program is to get the user to enter 2 numbers that is an even multiple of the other number. I am not sure how that part either. After finding 2 numbers that is an even multiple of the other number, i am supposed to display all the odd numbers between the two numbers. Thanks alot in advance.
import java.util.Scanner; //imports the java utillity scanner
public class MyPrompter{
public static void main(String[] args){
System.out.println("Odd number display");
Scanner input = new Scanner(System.in); //scans for user input and stores in "input"
int num1,num2; //declares the variables i need for the pgrm
try{ //try statement to check for user input errors
System.out.println("Please enter your first number: ");
num1 = input.nextInt(); //stores input for the first number
System.out.println("Please enter your second number: ");
num2 = input.nextInt(); //stores input for the second number
while((num1+num2)%2==0){ //while loop to find all the odd numbers between the 2 numbers
System.out.println();
}
}
catch(java.util.InputMismatchException e){ //if the above error is met, message will be sent to the user
System.out.println("Please enter a valid ROUNDED NUMBER!");
}
}
}
How about something like this:
int num1 = 10;
int num2 = 50;
int current = num1;
while (current < num2) {
if (current % 2 != 0) {
System.out.println(current);
}
current++;
}
Set current to equal num1, continue the loop while current is less than num2. For each iteration check if current is odd and output it if it is. Increment current by one.
Related
I got this question on exam review "Write psuedocode for a program that reads a sequence of integer values and decides whether or not it is a decreasing sequence. The program will first read in the number of values to process, followed by the values themselves. The output will be “Yes” if the sequence is decreasing, and “No” otherwise."
Here is my code, but it sometimes does not stop,(for example, when you input 3 2 1). Can someone help me to figure out where I was wrong? Thank you!
import java.util.Scanner;
public class DecreasingOrNot {
public static void main(String[] args){
int number1, number2;
boolean decrease = true;
Scanner input = new Scanner(System.in);
System.out.println("Enter a sequence of numbers: ");
number2 = input.nextInt();
while (decrease && input.hasNext()){
number1 = number2;
number2 = input.nextInt();
if (number1 < number2){
decrease = false;
}
}
if (decrease){
System.out.println("Yes");
}
else{
System.out.println("No");
}
}
}
Right now, you have no way of breaking out of the loop if the user keeps adding decreasing numbers (which is why it won't break out of the loop if the user enters something like 3 2 1).
So I've written a test class to test a program that will allow me to take in number of courses, letter grades, and course credits and then calculate total weighted points, total credits, and GPA within a loop designed for 3 courses max.
However, I need to validate the number of courses and prove that it will run after both an invalid and valid input have been entered.
I've gotten it so that will prompt the user for a valid number of courses after an invalid response, but once the valid response is input the program just stops instead of running like it is supposed to. Can anyone tell me why?
Here's my code:
import java.util.*;
import java.lang.*;
public class ComputeGpa
{
public static void main(String [] args)
{
Gpa grades1 = new Gpa();
Scanner in = new Scanner (System.in);
System.out.println("Enter number of courses: ");
int courses = in.nextInt();
if(courses > 0)
{
int i = 0;
while(i < 3)
{
System.out.println("Please enter a letter grade.");
String letter = in.next();
char result = letter.charAt(0);
System.out.println("How many credits was this class worth?");
int credits = in.nextInt();
grades1.addToTotals(result, credits);
i++;
}
System.out.printf("GPA: %.2f", grades1.calcGpa());
}
else
{
System.out.println("Number of courses must be greater than 0. Please enter a valid number of courses.");
courses = in.nextInt();
}
}
}
The output for that is as follows:
Enter number of courses:
-2
Number of courses must be greater than 0. Please enter a valid number of courses.
3
And then the program stops running. Where Am I going wrong? I thought the in.next() on the letter String would fix this problem but apparently I was wrong. Any ideas?
Your flow is currently if/else.
int foo = ...;
if(foo > 0) {
//your grade stuff
}
else {
//ask for reinput
}
What ends up happening is you catch the problem input once, but never give your flow the opportunity to check it again.
Instead, use a while loop over an if/else layout, to force re-entry until you get the exact information you want, then continue.
System.out.println("Enter number of courses: ");
int courses = in.nextInt();
while(courses < 0) {
System.out.println("Number of courses must be greater than 0. Please enter a valid number of courses.");
courses = in.nextInt();
}
int i = 0;
//...
I'm making a simple program that asks the user to input five numbers between 0-19. I would like to add something (like an if statement) after every number to make sure it's within that range. If not, the program should say "please read instructions again" and will then System.exit(0). This is the piece of the code that is relevant:
System.out.println("Please enter 5 numbers between 0 and 19");
System.out.print("1st Number: ");
userNum1 = scan.nextInt();
System.out.print("2nd Number: ");
userNum2 = scan.nextInt();
System.out.print("3rd Number: ");
userNum3 = scan.nextInt();
System.out.print("4th Number: ");
userNum4 = scan.nextInt();
System.out.print("5th Number: ");
userNum5 = scan.nextInt();
Any help would be greatly appreciated.
You can put this after each of your inputs, but you might want to think about putting this logic into its own method, then you can reuse the code and just call it with something like validateInput(userNum1);.
Replace val with your actual variable names.
if (val < 0 || val > 19) {
System.out.println("please read the instructions again");
System.exit(0);
}
First of all, I would create a for-loop that iterates N times, with N being the number of numbers you want to ask for (in your case, 5). Imagine your example with 50 numbers; it would be very repetitive.
Then, when you get each number with scan.nextInt() within your for-loop, you can validate however you want:
if (userNum < 0 || userNum > 19) {
// print error message, and quit here
}
Also, instead of just exiting when they input a number outside the range, you could have your logic inside a while loop so that it re-prompts them for the numbers. This way the user doesn't have to restart the application. Something like:
boolean runApplication = true;
while(runApplication) {
// do your for-loop with user input scanning
}
Then set the runApplication flag as needed based on whether or not the user put in valid numbers.
This code will do the trick for you, i added some securities :
public static void main(String[] args) {
int count = 1;
Scanner scan = new Scanner(System.in);
List<Integer> myNumbers = new ArrayList<Integer>();
System.out.println("Please enter 5 numbers between 0 and 19");
do {
System.out.println("Enter Number "+count+" ");
if(scan.hasNextInt()){
int input = scan.nextInt();
if(input >= 0 && input <= 19){
myNumbers.add(input);
count++;
}else{
System.out.println("Please read instructions again");
System.exit(0);
}
}else{
scan.nextLine();
System.out.println("Enter a valid Integer value");
}
}while(count < 6);
/* NUMBERS */
System.out.println("\n/** MY NUMBERS **/\n");
for (Integer myNumber : myNumbers) {
System.out.println(myNumber);
}
}
Hope it helps
Since you already know how many numbers you want the user to input, I suggest you use a for loop. It makes your code more elegant and you can add as many more entries as you want by changing the end condition of the loop. The only reason it looks long is because number 1, 2, 3 all end in a different format i.e firST secoND thiRD, but the rest of the numbers all end with TH. This is why I had to implement some if else statements inside the loop.
To explain the code, every time it loops it first tells the user the count of the number he/she is entering. Then numEntry is updated every time the loop loops, therefore you do not need to assign multiple inputs to multiple variables. It is more efficient to update the same variable as you go on. If the input the user inputs is less than 0 OR it is more than 19, the system exits after an error message.
System.out.println("Please enter a number between 0 and 19");
Scanner scan = new Scanner(System.in);
for(int i = 1; i <=5; i++){
if(i == 1)
System.out.println("1st Number");
else if(i == 2)
System.out.println("2nd Number");
else if(i == 3)
System.out.println("3rd Number");
else
System.out.println(i + "th Number");
int numEntry = scan.nextInt();
if(numEntry < 0 || numEntry > 19){
System.out.println("Please read instructions again.");
System.exit(1);
}
I'm trying to ask user to type how many numbers will be inputted and enter the values then add all the values.
import java.util.Scanner;
public class sum {
static Scanner sc = new Scanner(System.in);
public static void main(String[] args){
int counter = 1;
int values = 0;
int times;
System.out.println("How many numbers will you input?: ");
times = sc.nextInt();
while(counter == times){
System.out.println("Enter your number: ");
values = values + sc.nextInt();
counter ++;
}
System.out.println("Your sum is " + values);
}
}
Your logic for the while loop is incorrect.
while(counter == times)
will only be true if counter and times have the same value. So if you would want to input two numbers, your while loop wouldn't even get executed. What you want is for the while loop to run until counter == times. So, your logic should be
while(counter != times)
Furthermore, you should start your counter at zero, instead of one. This is because it now means that you already inputted one number, which you didn't.
Alternatively, you could use the following snippet
while (sc.hasNextInt()) {
values += sc.nextInt()
}
This simple loop will go through all the integers inputted in the command line one by one, until there is no next integer (you type for example a letter).
In that case, you don't need to ask the user how many numbers he/she will input, as you will check it yourself.
User inputs numbers one by one and then once they type in an invalid number (has to be from 1-200) the program calculates the average of the numbers that were inputted.
I'm just wondering what would the code be for this. I know the one for inputting one piece of data. Example would be:
`Scanner in = new Scanner(System.in);
String numberOfShoes = "";
System.out.println("Enter the number of shoes you want: (0-200) ");
numberOfShoes = in.nextLine();`
this is just an example, but this time I want the user to input a lot of numbers. I know I'm going to include a loop somewhere in this and I have to stop it once it contains an invalid number (using a try catch block).
* I would also like to add that once the user inputs another number it always goes to the next line.
Just use a while loop to continue taking input until a condition is met. Also keep variables to track the sum, and the total number of inputs.
I would also suggest having numberOfShoes be an int and use the nextInt() method on your Scanner (so you don't have to convert from String to int).
System.out.println("Enter your number of shoes: ");
Scanner in = new Scanner(System.in);
int numberOfShoes = 0;
int sum = 0;
int numberOfInputs = 0;
do {
numberOfShoes = in.nextInt();
if (numberOfShoes >= 1 && numberOfShoes <= 200) { // if valid input
sum += numberOfShoes;
numberOfInputs++;
}
} while (numberOfShoes >= 1 && numberOfShoes <= 200); // continue while valid
double average = (double)sum / numberOfInputs;
System.out.println("Average: " + average);
Sample:
Enter your number of shoes:
5
3
7
2
0
Average: 4.25
It added 5 + 3 + 7 + 2 to get the sum of 17. Then it divided 17 by the numberOfInputs, which is 4 to get 4.25
you are almost there.
Logic is like this,
Define array
Begin Loop
Accept the number
check if its invalid number [it is how u define a invalid number]
if invalid, Exit Loop
else put it in the array
End Loop
Add all numbers in your array
I think you need to do something like this (which #Takendarkk suggested):
import java.util.Scanner;
public class shoes {
public void main(String[] args){
int input = 0;
do{
Scanner in = new Scanner(System.in);
String numberOfShoes = "";
System.out.println("Enter the number of shoes you want: (0-200) ");
numberOfShoes = in.nextLine();
input = Integer.parseInt(numberOfShoes);
}while((input>=0) && (input<=200));
}
}
you can use for loop like this
for(::)
{
//do your input and processing here
if(terminating condition satisified)
{
break;
}
}