Develop Reference

Not sure how to do a while loop in this situation

I am writing a program to take the input for a sequence
import java.util.Scanner;
public class FibonacciCode {
public static void main(String[] args) {
System.out.println("Enter a number");
int count, number0 = 0, number1 = 1, loop = 0;
Scanner userInput = new Scanner(System.in);
count = userInput.nextInt();
while(loop > count)
{
System.out.print(number0 + ", ");
int sum = number0 + number1;
number0 = number1;
number1 = sum;
loop++;
}
}
}

This should be a usable implementation:
public class Menu {
public static void main(String[] args) {
Scanner a = new Scanner(System.in);
boolean orderCompleted = false;
while(!orderCompleted) {
printMenu();
String orderString = a.nextLine();
int order = Integer.parseInt(orderString);
int total = 0;
if(order == 1) {
} else if(order == 2) {
} else if(order == 3) {
} else if(order == 4) {
} else if(order == 5) {
}
System.out.println("Would you like to order more? Press 'y' to continue or 'n' to finish order.");
orderString = a.nextLine();
if(orderString.equals("n")){
orderCompleted = true;
}
}
}
private static void printMenu() {
System.out.println("Welcome to Hess Burgers");
System.out.println("1- Cheeseburger.............$7");
System.out.println("2- Barbeque Burger..........$8");
System.out.println("3- Southwestern Burger......$9");
System.out.println("4- Bacon Cheeseburger.......$10");
System.out.println("5- Double Stack Burger......$11");
System.out.println("");
System.out.print("Please enter your order selection:");
}
}
I pulled the menu printing to a separate method, and re-used scanner a as well as re-using the orderString. The while loop checks a completedOrder boolean flag, so that it can be used to do completion tasks prior to exiting the order loop if need be.

import java.util.Scanner;
public class FibonacciCode {
public static void main(String[] args) {
System.out.println("Enter a number");
int count, number0 = 0, number1 = 1, loop = 0;
Scanner userInput = new Scanner(System.in);
count = userInput.nextInt();
while(loop > count)
{
System.out.print(number0 + ", ");
int sum = number0 + number1;
number0 = number1;
number1 = sum;
loop++;
}
}
}

A while loop does whatever is in the block as long as the condition is true, in your case, you are simply repeating order = b.nextInt() until something other than 'y' is given as input
while (continuePlay= b.nextLine().equalsIgnoreCase ("y")) {
order = b.nextInt(); // This is inside the block
}
you should use a do while loop instead, like so:
do{
System.out.println("Welcome to Hess Burgers");
System.out.println("1- Cheeseburger.............$7");
System.out.println("2- Barbeque Burger..........$8");
System.out.println("3- Southwestern Burger......$9");
System.out.println("4- Bacon Cheeseburger.......$10");
System.out.println("5- Double Stack Burger......$11");
System.out.println(" ");
System.out.print("Please enter your order selection:");
Scanner a = new Scanner(System.in);
int order = a.nextInt();
int total = 0;
boolean continuePlay = true;
if (order == 1 ) {
} else if (order == 2) {
} else if (order == 3) {
} else if (order == 4) {
} else if (order == 5) {
}
Scanner b = new Scanner(System.in);
System.out.println("Would you like to order more? Press 'y' to continue or 'n' to finish order.");
} while (continuePlay= b.nextLine().equalsIgnoreCase ("y"));
Also I'd recommend reading some basic programming books or tutorials instead of going directly to Stack Overflow.

How can I get my program back on track when printing out all student records?

import java.util.Scanner;
public class MainBinaryTreeArray
{
public static void main(String[] args)
{
int choice;
Scanner scan= new Scanner(System.in);
BinaryTreeArray data = new BinaryTreeArray();
Listing l1 = new Listing("Carol", 4354, 3.2);
Listing l2 = new Listing("Timothy", 2353, 4.0);
Listing l3 = new Listing("Dean", 4544, 2.4);
Listing l4 = new Listing("Sue", 3445, 3.0);
data.insert(l1);
data.insert(l2);
data.insert(l3);
data.insert(l4);
do
{
// Choose which operation by entering a number
System.out.println("*****************(Menu Operations:)******************");
System.out.println(" (Press 1). Insert.");
System.out.println(" (Press 2). Fetch.");
System.out.println(" (Press 5). Output all student records.");
System.out.println(" (Press 6). Exit the program.");
System.out.println("Enter your choice: ");
choice = scan.nextInt();
switch(choice)
{
case 1:
System.out.println("Are students inserted: " + data.insert(l1));
break;
case 2:
System.out.println("The student's info that's fetched: ");
System.out.print(data.fetch("Timothy"));
break;
case 5:
System.out.print("Output all the student's records: ");
data.showAll();
}
}while(choice!=6);
}
}
public class BinaryTreeArray
{
private Listing[] data;
private int size;
public BinaryTreeArray()
{
size = 100;
data = new Listing[size];
}
public void showAll()
{
for(int i=0; i<size; i++)
System.out.print(data[i] + " ");
}
public boolean insert(Listing newListing)
{
int i = 0;
while(i < size && data[i]!= null)
{
if(data[i].getKey().compareTo(newListing.getKey()) > 0)
i = 2 * i + 1;
else
i = 2 * i + 2;
}
if(i >= size)
return false;
else
{
data[i] = newListing.deepCopy();
return true;
}
}
public Listing fetch(String targetKey)
{
int i= 0;
while(i< size && data[i]!= null && data[i].getKey()!=targetKey)
{
if(data[i].getKey().compareTo(targetKey) > 0)
i = 2 * i + 1;
else
i = 2 * i + 2;
}
if(i >= size || data[i] == null)
return null;
else
return data[i].deepCopy();
}
}
public class Listing implements Comparable<Listing>
{ private String name; // key field
private int ID;
private double GPA;
public Listing(String n, int id, double gpa)
{ name = n;
ID = id;
GPA = gpa;
}
public String toString()
{ return("Name is " + " " + name +
"\nID is" + " " + ID +
"\nGPA is" + " " + GPA + "\n");
}
public Listing deepCopy()
{ Listing clone = new Listing(name, ID, GPA);
return clone;
}
public int compareTo(Listing other)
{
return this.name.compareTo(other.getKey());
}
public String getKey()
{
return name;
}
}// end of class Listing
Hello All,
My java program compiles fine, but I am having a terrible and miserable time with getting my program to stop printing all those nulls when I output all student records in my BinaryTreeArray. Here is complete program. Any suggestions? Please do give any advice. So to make what I am saying clear, I need help with understanding why when I print out student records it includes a whole bunch of extra nulls that really have no purpose and just make my program look crazy. Any solutions to this problem?

When you initialize the BinaryTreeArray(), you set the field variable "size" to 100 and use this to initialize the data Listing[] array. When you print out the data, the loop uses the same "size" variable so you get all 100 entries, including the null entries. A simple solution would be to filter the data for null when you show all.
public class BinaryTreeArray
{
...
public void showAll()
{
for(int i=0; i<size; i++)
{
if (data[i] != null)
System.out.print(data[i] + " ");
}
}
...
}
An alternate solution would be to change your use of size to maxSize and then create a variable size that is incremented as you insert listings.

Counting occurrence of attributes inside the objects of a Java Array

I have created an array of 25 Flower objects. Each flower object holds the flower name(String), flower color(String), presence of thorns(boolean), and flower scent(String). These attributes are handled by the 'Flower' class. I have pasted both classes in case the error is being caused by either class. The user inputs all of the attributes of the flowers when the menu prompts for the information. After the user enters all of the flowers they want to, I need to be able to print out the entire array and a counter of how many of each flower there are. For instance, if the user puts in 10 flowers and there are 3 Roses, 2 Lilly's, 3 Dandelions, and 2 Orchids, I need to print the entire array and then print the number each flower was present. The format for the display is:
Flower name: Rose Flower color: Red Flower has thorns: true Flower scent: Sweet
Rose - 3
Lilly - 3
Dandelion - 3
Orchid - 2
I am able to print out the array as shown, but cannot get the count variable to work properly. I do not need to sort this array.
Another issue I am getting in an OutOfBounds error. I can only put in 24 flowers before I encounter this error. The 25th flower triggers it. I thought this was covered by the addFlower index counter, but obviously, I was incorrect.
This assignment does not allow the use of ArrayList, which would make this much simpler. We have not explored error handling yet either.
Current code is:
package assignment2;
import java.util.Scanner;
public class Assignment2
{
public static void main(String[] args)
{
new Assignment2();
}
public Assignment2()
{
Scanner input = new Scanner(System.in);
Flower flowerPack[] = new Flower[25];
System.out.println("Welcome to my flower pack interface.");
System.out.println("Please select a number from the options below");
System.out.println("");
while (true)
{
// Give the user a list of their options
System.out.println("1: Add an item to the pack.");
System.out.println("2: Remove an item from the pack.");
System.out.println("3: Search for a flower.");
System.out.println("4: Display the flowers in the pack.");
System.out.println("0: Exit the flower pack interfact.");
// Get the user input
int userChoice = input.nextInt();
switch (userChoice)
{
case 1:
addFlower(flowerPack);
break;
case 2:
removeFlower(flowerPack);
break;
case 3:
searchFlowers(flowerPack);
break;
case 4:
displayFlowers(flowerPack);
break;
case 0:
System.out.println("Thank you for using the flower pack interface. See you again soon!");
input.close();
System.exit(0);
}
}
}
private void addFlower(Flower flowerPack[])
{
String flowerName; // Type of flower
String flowerColor; // Color of the flower
Boolean hasThorns = false; // Have thorns?
String flowerScent; // Smell of the flower
int index = 0;
Scanner input = new Scanner(System.in);
System.out.println("What is the name of flower is it?");
flowerName = input.nextLine();
System.out.println("What color is the flower?");
flowerColor = input.nextLine();
System.out.println("Does the flower have thorns?");
System.out.println("Choose 1 for yes, 2 for no");
int thorns = input.nextInt();
if(thorns == 1)
{
hasThorns = true;
}
input.nextLine();
System.out.println("What scent does the flower have?");
flowerScent = input.nextLine();
Flower fl1 = new Flower(flowerName, flowerColor, hasThorns, flowerScent);
for(int i = 0; i < flowerPack.length; i++)
{
if(flowerPack[i] != null)
{
index++;
if(index == flowerPack.length)
{
System.out.println("The pack is full");
}
}
else
{
flowerPack[i] = fl1;
break;
}
}
}
private void removeFlower(Flower flowerPack[])
{
Scanner input = new Scanner(System.in);
System.out.println("What student do you want to remove?");
displayFlowers(flowerPack);
System.out.println("Choose 1 for the first flower, 2 for the second, etc" );
int index = input.nextInt();
index = index - 1;
for (int i = 0; i < flowerPack.length - 1; i++)
{
if(flowerPack[i] != null && flowerPack[i].equals(flowerPack[index]))
{
flowerPack[i] = flowerPack[i + 1];
}
}
}
private void searchFlowers(Flower flowerPack[])
{
Scanner input = new Scanner(System.in);
String name;
System.out.println("What flower would you like to search for?");
name = input.nextLine();
boolean found = false;
for (int i = 0; i < flowerPack.length; i++)
{
if (flowerPack[i].getFlowerName().equalsIgnoreCase(name))
{
found = true;
break;
}
}
if (found)
{
System.out.println("We found your flower.");
}
else
{
System.out.println("That flower was not found.");
}
}
private void displayFlowers(Flower flowerPack[])
{
int count = 1;
for(int i = 0; i < flowerPack.length; i++)
{
if (flowerPack[i] != null)
{
if (flowerPack[i].equals(flowerPack[i+1]))
{
count++;
}
else
{
System.out.println(flowerPack[i]);
count = 1;
}
}
else
{
if (flowerPack[i] == null)
{
break;
}
}
}
}
}
The Flower class is below.
package assignment2;
public class Flower
{
#Override
public String toString()
{
return "Flower name: " + this.getFlowerName() + "\t" +
"Flower color: " + this.getFlowerColor() + "\t" +
"Flower has thorns: " + this.getHasThorns() + "\t" +
"Flower scent: " + this.getFlowerScent() + "\t" ;
}
private String flowerName;
private String flowerColor;
private Boolean hasThorns;
private String flowerScent;
Flower(String flowerName, String flowerColor, Boolean hasThorns, String flowerScent)
{
this.flowerName = flowerName;
this.flowerColor = flowerColor;
this.hasThorns = hasThorns;
this.flowerScent = flowerScent;
}
String getFlowerName()
{
return flowerName;
}
private void setFlowerName(String flowerName)
{
this.flowerName = flowerName;
}
private String getFlowerColor()
{
return flowerColor;
}
private void setFlowerColor()
{
this.flowerColor = flowerColor;
}
private Boolean getHasThorns()
{
return hasThorns;
}
private void setHasThorns()
{
this.hasThorns = hasThorns;
}
private String getFlowerScent()
{
return flowerScent;
}
private void setFlowerScent()
{
this.flowerScent = flowerScent;
}
}

private void displayFlowers(Flower flowerPack[])
{
String[] usedNames = new String[flowerPack.length];
int[] nameCounts = new int[flowerPack.length];
int usedNamesCount = 0;
for (int i = 0; i < flowerPack.length; i++)
{
Flower flower = flowerPack[i];
if (flower == null)
{
continue;
}
int nameIndex = -1;
for (int j = 0; j < usedNamesCount; j++)
{
String usedName = usedNames[j];
if (flower.getFlowerName().equals(usedName))
{
nameIndex = j;
break;
}
}
if (nameIndex != -1)
{
nameCounts[nameIndex] += 1;
}
else
{
usedNames[usedNamesCount] = flower.getFlowerName();
nameCounts[usedNamesCount] += 1;
usedNamesCount++;
}
}
for (int i = 0; i < usedNamesCount; i++)
{
System.out.println(usedNames[i] + "s - " + nameCounts[i]);
}
}

Simple ATM task, problems with array.

I want to overwrite the first element of my transaction array when it gets full. So when I print the array, it is always showing the latest transactions.
I think the problem is in the moveTrans method or the findNr method but I'm not sure and I can't figure out what is wrong.
Code:
import java.util.Scanner;
import java.util.*;
public class BankoTest {
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
int amount = 0;
int choice = 0;
int [] trans = new int[4];
int sum;
int balance = 0;
while (choice != 4)
{
choice = menu();
switch(choice)
{
case 1://
System.out.print("Deposit. Amount? :");
amount = scan.nextInt();
balance = balance + amount;
makeTransactions(trans, amount);
break;
case 2://
System.out.print("Withdra. Amount?");
amount = scan.nextInt();
balance = balance - amount;
makeTransactions(trans, -amount);
break;
case 3:
showTransactions(trans, balance);
break;
case 4:
System.out.println("Thank you. ");
break;
}
}
}
public static int menu()
{
Scanner scan = new Scanner(System.in);
int choice = 0;
System.out.println("1. Deposit ");
System.out.println("2. Withdraw ");
System.out.println("3. Saldo ");
System.out.println("4. End ");
System.out.println();
System.out.println("Choice: ");
choice = scan.nextInt();
return choice;
}
public static void showTransactions(int [] trans, int balance)
{
System.out.println();
System.out.println("Transactions summary :");
System.out.println();
for(int i = 0; i < trans.length-1; i++)
{
if(trans[i] == 0)
{
System.out.print("");
}
else
{
System.out.print(trans[i] + "\n");
balance = balance + trans[i];
}
}
// Printing saldo.
System.out.println();
System.out.println("Current balance: " + balance + " kr" + "\n" );
System.out.println();
}
//Puts amount last among the transactions that are stored in the array. Using the findNr method to find the first available spot
//in the array. moveTrans is used to make room for the new transaction when the array is full.
public static void makeTransactions(int [] trans, int amount )
{
int position = findNr(trans);
if(position == -1)
{
moveTrans(trans);
position = findNr(trans);
trans[position] = amount;
}
else
{
trans[position] = amount;
}
}
public static int findNr(int [] trans)
{
int position = -1;
for(int i = 0; i <= trans.length-1; i++)
{
if(trans[i] == 0)
{
position = i;
break;
}
}
return position;
}
public static void moveTrans(int [] trans)
{
for(int i = 0; i < trans.length-1; i++)
trans[0] = trans[i + 1] ;
}
}

just modify the following method alone
public static void makeTransactions(int[] trans, int amount) {
int position = findNr(trans);
if (position == -1) {
moveTrans(trans);
position = findNr(trans);
trans[position] = amount;
} else {
if (position != 0 && position == trans.length - 1) {
// shift the elements back
for (int i = 0; i < position; i++)
trans[i] = trans[i] + 1;
trans[position - 1] = amount;
}else
trans[position] = amount;
}
}

Please check this it may help some thing to you
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int amount = 0;
int choice = 0;
int[] trans = new int[4];
int sum;
int balance = 0;
while (choice != 4) {
choice = menu();
switch (choice) {
case 1://
System.out.print("Deposit. Amount? :");
amount = scan.nextInt();
balance = balance + amount;
makeTransactions(trans, amount);
break;
case 2://
System.out.print("Withdra. Amount?");
amount = scan.nextInt();
balance = balance - amount;
makeTransactions(trans, -amount);
break;
case 3:
showTransactions(trans, balance);
break;
case 4:
System.out.println("Thank you. ");
break;
}
}
}
public static int menu() {
Scanner scan = new Scanner(System.in);
int choice = 0;
System.out.println("1. Deposit ");
System.out.println("2. Withdraw ");
System.out.println("3. Saldo ");
System.out.println("4. End ");
System.out.println();
System.out.println("Choice: ");
choice = scan.nextInt();
return choice;
}
public static void showTransactions(int[] trans, int balance) {
System.out.println();
System.out.println("Transactions summary :");
System.out.println();
for (int i = 0; i < trans.length - 1; i++) {
if (trans[i] == 0) {
System.out.print("");
}
else {
System.out.print(trans[i] + "\n");
// balance = trans[i];
}
}
// Printing saldo.
System.out.println();
System.out.println("Current balance: " + balance + " INR" + "\n");
System.out.println();
}
// Puts amount last among the transactions that are stored in the array.
// Using the findNr method to find the first available spot
// in the array. moveTrans is used to make room for the new transaction when
// the array is full.
public static void makeTransactions(int[] trans, int amount) {
int position = findNr(trans);
if (position == -1) {
moveTrans(trans);
System.out.println("Your transaction limit is over.");
// position = findNr(trans);
// System.out.println("Position -------> "+position);
// trans[position] = amount;
} else {
trans[position] = amount;
}
}
public static int findNr(int[] trans) {
int position = -1;
for (int i = 0; i <= trans.length - 1; i++) {
if (trans[i] == 0) {
position = i;
break;
}
}
return position;
}
public static void moveTrans(int[] trans) {
System.out.println("------Your Transaction Details----------");
for (int i = 0; i < trans.length; i++) {
System.out.println("Transation " + (i + 1) + " :: " + trans[i]);
trans[0] = trans[i];
}
System.out.println("----------------------------------------");
}

How to Loop a simple program in Java?

I am trying to code a simple program in which the user can view and update a list of NBA player's racing for the MVP Trophy. However I have failed in the past to code a program in which can loop for however long the user decides to. I want the program to have the options 1. Go Back & 2. Exit but I cannot figure out how to loop it. Here is my Rank.java & AdminAccount.java. Hope it is not confusing to understand, thank you for reading.
import java.util.Scanner;
public class Rank {
String player[] = { "Stephen Curry", "Russel Westbrook", "Kevind Durant", "LeBron James", "Kawhi Leonard" };
Scanner rankInput = new Scanner(System.in);
Scanner playerInput = new Scanner(System.in);
int rank;
String playerUpdate;
public void Rank() {
System.out.println("Rank\tPlayer");
for (int counter = 0; counter < player.length; counter++) {
System.out.println(counter + 1 + "\t" + player[counter]);
}
}
public void updateRank() {
System.out.print("Select rank to update: ");
rank = rankInput.nextInt();
if (rank == 1) {
System.out.print("\nPlayer Name: ");
playerUpdate = playerInput.nextLine();
player[0] = playerUpdate;
} else if (rank == 2) {
System.out.print("\nPlayer Name: ");
playerUpdate = playerInput.nextLine();
player[1] = playerUpdate;
} else if (rank == 3) {
System.out.print("\nPlayer Name: ");
playerUpdate = playerInput.nextLine();
player[2] = playerUpdate;
} else if (rank == 4) {
System.out.print("\nPlayer Name: ");
playerUpdate = playerInput.nextLine();
player[3] = playerUpdate;
} else if (rank == 5) {
System.out.print("\nPlayer Name: ");
playerUpdate = playerInput.nextLine();
player[4] = playerUpdate;
}
}
}
import java.util.Scanner;
public class AdminAccount {
public static void main(String[] args) {
Rank rank = new Rank();
Scanner adminInput = new Scanner(System.in);
Scanner exitInput = new Scanner(System.in);
boolean keepRunning = true;
// menu variables
int menuOption;
int exitOption;
while (keepRunning) {
System.out.println("*** NBA MVP Race Administor Account ***");
System.out.print("\n1.Ranking 2.Update\t- ");
menuOption = adminInput.nextInt();
System.out.println("");
if (menuOption == 1) {
rank.Rank();
} else if (menuOption == 2) {
rank.updateRank();
}
}
}
}

Just add an "exit" option to your loop:
while(keepRunning){
System.out.println("*** NBA MVP Race Administor Account ***");
System.out.print("\n1.Ranking 2.Update 3.Exit\t- ");
menuOption = adminInput.nextInt();
System.out.println("");
if(menuOption == 1)
{
rank.Rank();
}
else if(menuOption == 2)
{
rank.updateRank();
}
else
{
keepRunning = false;
}
}

This a sample code using arrays
This Program Uses Do.... While Loop to Loop over a whole program when there is a user prompt.
package doWhileLoop;
import java.util.Scanner;
public class doWhileLoop {
public static void main(String[] args) {
//this is a program to prompt a user to continue or pass using the do while loop
String programCounter;
do {
int sum=0;
int list[] = new int[3];
Scanner in = new Scanner(System.in);
System.out.println("Enter 3 numbers to be added: ");
for (int i = 0; i < 3; i++) {
list[i] = in.nextInt();
sum+= list[i];
}
System.out.println("sum = "+ sum);
System.out.println("Enter Yes to continue or No to exit........");
programCounter = in.next();
}
while (programCounter.equals("yes"));
}
}