Develop Reference

My array is only remembering last last element entered and histogram is not printing right

import java.util.Scanner;
public class RainRecording {
private int choice;
private Scanner input;
private String site;
private int days;
private int daysCounter;
private int[] rainRecorded;
private int[] rainEntered;
private float lattitude;
private float longitude;
private String message1;
private String message2;
private String message3;
private String message4;
private String message5;
private String message6;
// declare name of variable
public RainRecording() {
// declare value of variable
this.message1 = "Site";
this.message2 = "lattitude";
this.message3 = "longitude";
this.message4 = "Window";
this.message5 = "days";
this.message6 = ":";
this.daysCounter = 0;
this.input = new Scanner(System.in);
mainMenu();
}
private void mainMenu() {
System.out.println("");
System.out.println("*** Rain Gauge Menu ***");
System.out.println(" 1: Create rain gauge");
System.out.println(" 2: Display rain gauge details");
System.out.println(" 3: Add daily rainfall measurement");
System.out.println(" 4: Display rainfall histogram");
System.out.println(" 5: Get maximum rainfall");
System.out.println(" 6: Check rainfall is below threshold");
System.out.println(" 7: Display anaylsis");
System.out.println(" 8: Exit");
System.out.print("Please enter your selection: ");
Chosen();
}
private void Chosen() {
this.choice = Integer.parseInt(input.nextLine());
switch (choice) {
case 1:
createGauge();
break;
case 2:
gaugeDetails();
break;
case 3:
int i = 0;
while( i < this.days || this.daysCounter == this.days) {
if (this.daysCounter == this.days) {
System.out.printf("Error - system full\n");
mainMenu();
}
if (this.days < 1) {
mainMenu();
} else {
this.rainRecorded = new int[this.days];
System.out.printf("Please enter rainfall for the current day: ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
this.rainEntered = new int[this.daysCounter];
mainMenu();
}
i++;
}
break;
case 4:
System.out.printf("\n");
displayHistogram();
break;
case 5:
break;
case 6:
break;
case 7:
break;
case 8:
break;
default:
System.out.println("Invalid input, try again");
mainMenu();
}
while (choice != 8)
;
}
private void createGauge() {
System.out.printf("\nPlease enter the name of the site :");
this.site = input.nextLine();
System.out.printf("Please enter the number of days to record :");
this.days = Integer.parseInt(input.nextLine());
System.out.printf("Please enter the lattitute :");
this.lattitude = Float.parseFloat(input.nextLine());
System.out.printf("Please enter the longitude :");
this.longitude = Float.parseFloat(input.nextLine());
mainMenu();
}
private void gaugeDetails() {
if (this.days > 0) {
System.out.printf("%-9s %-3s %s \n", this.message1, this.message6, this.site);
System.out.printf("%s %-3s % 09.4f\n", this.message2, this.message6, this.lattitude);
System.out.printf("%s %-3s %9.4f\n", this.message3, this.message6, this.longitude);
System.out.printf("%-9s %-3s %-2d%s \n", this.message4, this.message6, this.days, this.message5);
mainMenu();
} else {
mainMenu();
}
}
private void displayHistogram() {
for (int i = 0; i < this.rainEntered.length; i++) {
for (int j = 0; j < this.rainRecorded[i] - 1; j++) {
System.out.print("*");
}
System.out.println(i);
}
System.out.print("");
mainMenu();
}
public static void main(String[] args) {
#SuppressWarnings("unused")
RainRecording objName;
objName = new RainRecording();
}
}
I guys i being struck on this for a couple of days in my switch statement in case 3 is where i create my elements to enter into my array , but in seems to only remember the last array entered when i print my histogram out in case 4 displayHistogram(); and this is where my histogram is printing wrong as well.
So to issues my array isn't recording property and histogram is printing wrong.
For example users chooses 3 days to enter and values are 10,20,30, and when i print histogram its prints this.
0
1
*****************************2
What i want this below , one * for ever ten mills of rain with index printed first.
0 *
1 **
2 **

You need to move the initialisation of this.rainRecorded to createGauge method and update the displayHistogram to print as required. You can try the following:
import java.util.Scanner;
public class RainRecording {
private int choice;
private Scanner input;
private String site;
private int days;
private int daysCounter;
private int[] rainRecorded;
private int[] rainEntered;
private float lattitude;
private float longitude;
private String message1;
private String message2;
private String message3;
private String message4;
private String message5;
private String message6;
// declare name of variable
public RainRecording() {
// declare value of variable
this.message1 = "Site";
this.message2 = "lattitude";
this.message3 = "longitude";
this.message4 = "Window";
this.message5 = "days";
this.message6 = ":";
this.daysCounter = 0;
this.input = new Scanner(System.in);
mainMenu();
}
private void mainMenu() {
System.out.println("");
System.out.println("*** Rain Gauge Menu ***");
System.out.println(" 1: Create rain gauge");
System.out.println(" 2: Display rain gauge details");
System.out.println(" 3: Add daily rainfall measurement");
System.out.println(" 4: Display rainfall histogram");
System.out.println(" 5: Get maximum rainfall");
System.out.println(" 6: Check rainfall is below threshold");
System.out.println(" 7: Display anaylsis");
System.out.println(" 8: Exit");
System.out.print("Please enter your selection: ");
Chosen();
}
private void Chosen() {
this.choice = Integer.parseInt(input.nextLine());
switch (choice) {
case 1:
createGauge();
break;
case 2:
gaugeDetails();
break;
case 3:
int i = 0;
while( i < this.days || this.daysCounter == this.days) {
if (this.daysCounter == this.days) {
System.out.printf("Error - system full\n");
mainMenu();
}
if (this.days < 1) {
mainMenu();
} else {
System.out.printf("Please enter rainfall for the current day: ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
this.rainEntered = new int[this.daysCounter];
mainMenu();
}
i++;
}
break;
case 4:
System.out.printf("\n");
displayHistogram();
break;
case 5:
break;
case 6:
break;
case 7:
break;
case 8:
break;
default:
System.out.println("Invalid input, try again");
mainMenu();
}
while (choice != 8)
;
}
private void createGauge() {
System.out.printf("\nPlease enter the name of the site :");
this.site = input.nextLine();
System.out.printf("Please enter the number of days to record :");
this.days = Integer.parseInt(input.nextLine());
this.rainRecorded = new int[this.days]; // move the array initialization here
System.out.printf("Please enter the lattitute :");
this.lattitude = Float.parseFloat(input.nextLine());
System.out.printf("Please enter the longitude :");
this.longitude = Float.parseFloat(input.nextLine());
mainMenu();
}
private void gaugeDetails() {
if (this.days > 0) {
System.out.printf("%-9s %-3s %s \n", this.message1, this.message6, this.site);
System.out.printf("%s %-3s % 09.4f\n", this.message2, this.message6, this.lattitude);
System.out.printf("%s %-3s %9.4f\n", this.message3, this.message6, this.longitude);
System.out.printf("%-9s %-3s %-2d%s \n", this.message4, this.message6, this.days, this.message5);
mainMenu();
} else {
mainMenu();
}
}
private void displayHistogram() {
for (int i = 0; i < this.rainEntered.length; i++) {
System.out.print(i + " ");
for (int j = 0; j < this.rainRecorded[i] - 1; j += 10 ) {
System.out.print("*");
}
System.out.println();
}
mainMenu();
}
public static void main(String[] args) {
#SuppressWarnings("unused")
RainRecording objName;
objName = new RainRecording();
}
}

So, your codes a little bit over the place and I've had some issues trying to understand the basic intent, for example
private int[] rainRecorded;
private int[] rainEntered;
I'm not sure what the intention is for these two variables. So in my example, I've discarded rainEntered for the time been.
So, your first problem starts here...
while( i < this.days || this.daysCounter == this.days) {
if (this.daysCounter == this.days) {
System.out.printf("Error - system full\n");
mainMenu();
}
if (this.days < 1) {
mainMenu();
} else {
this.rainRecorded = new int[this.days];
System.out.printf("Please enter rainfall for the current day: ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
this.rainEntered = new int[this.daysCounter];
mainMenu();
}
i++;
}
First, I'd remove the need to for the two exit conditions, as it is going to make it more difficult to reasons about
Next, the checks for the validity of the data should be done outside of the loop and I'd also avoid calling mainMenu from within it, this is going to quickly put you in a strange place.
But, my main problem is with
this.rainRecorded = new int[this.days];
System.out.printf("Please enter rainfall for the current day: ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
this.rainEntered = new int[this.daysCounter];
You keep creating new instances of both this.rainRecorded and this.rainEntered, meaning that each time the loop runs, you've lost anything that was previous entered.
So, in my "simplified" version, I modified it down to something like...
if (this.days < 1) {
System.out.println("Invalid number of days");
return;
}
if (this.daysCounter == this.days) {
System.out.printf("Error - system full\n");
return;
}
while (this.daysCounter < this.days) {
System.out.printf("Please enter rainfall for the day " + (daysCounter + 1) + ": ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
}
I then simplified the histogram workflow as well, but I'm still trying to get my head around what rainEntered is suppose to do...
private void displayHistogram() {
for (int amount : rainRecorded) {
for (int count = 0; count < amount; count++) {
System.out.print("*");
}
System.out.println(" " + amount);
}
}
One last thing I also did, was to remove all the calls to mainMenu and instead relied on a simple do-while loop to reprint the menu each time it returned from Chosen method
private void mainMenu() {
do {
System.out.println("");
System.out.println("*** Rain Gauge Menu ***");
System.out.println(" 1: Create rain gauge");
System.out.println(" 2: Display rain gauge details");
System.out.println(" 3: Add daily rainfall measurement");
System.out.println(" 4: Display rainfall histogram");
System.out.println(" 5: Get maximum rainfall");
System.out.println(" 6: Check rainfall is below threshold");
System.out.println(" 7: Display anaylsis");
System.out.println(" 8: Exit");
System.out.print("Please enter your selection: ");
Chosen();
} while (shouldContinue);
}
This simplifies the workflow, as it's easier to reason about where you are at any point in the execution of the program, instead of wondering why when, under some condition, when you chose something from the menu, you end up in some other part of the program instead.
Example
import java.util.Scanner;
public class RainRecording {
private int choice;
private Scanner input;
private String site;
private int days;
private int daysCounter;
private int[] rainRecorded;
//private int[] rainEntered;
private float lattitude;
private float longitude;
private String message1;
private String message2;
private String message3;
private String message4;
private String message5;
private String message6;
private boolean shouldContinue = true;
// declare name of variable
public RainRecording() {
// declare value of variable
this.message1 = "Site";
this.message2 = "lattitude";
this.message3 = "longitude";
this.message4 = "Window";
this.message5 = "days";
this.message6 = ":";
this.daysCounter = 0;
this.input = new Scanner(System.in);
mainMenu();
}
private void mainMenu() {
do {
System.out.println("");
System.out.println("*** Rain Gauge Menu ***");
System.out.println(" 1: Create rain gauge");
System.out.println(" 2: Display rain gauge details");
System.out.println(" 3: Add daily rainfall measurement");
System.out.println(" 4: Display rainfall histogram");
System.out.println(" 5: Get maximum rainfall");
System.out.println(" 6: Check rainfall is below threshold");
System.out.println(" 7: Display anaylsis");
System.out.println(" 8: Exit");
System.out.print("Please enter your selection: ");
Chosen();
} while (shouldContinue);
}
private void Chosen() {
this.choice = Integer.parseInt(input.nextLine());
switch (choice) {
case 1:
createGauge();
break;
case 2:
gaugeDetails();
break;
case 3:
if (this.days < 1) {
System.out.println("Invalid number of days");
return;
}
if (this.daysCounter == this.days) {
System.out.printf("Error - system full\n");
return;
}
while (this.daysCounter < this.days) {
System.out.printf("Please enter rainfall for the day " + (daysCounter + 1) + ": ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
}
break;
case 4:
System.out.printf("\n");
displayHistogram();
break;
case 5:
break;
case 6:
break;
case 7:
break;
case 8: shouldContinue = false;
break;
default:
System.out.println("Invalid input, try again");
}
}
private void createGauge() {
System.out.printf("\nPlease enter the name of the site :");
this.site = input.nextLine();
System.out.printf("Please enter the number of days to record :");
this.days = Integer.parseInt(input.nextLine());
System.out.printf("Please enter the lattitute :");
this.lattitude = Float.parseFloat(input.nextLine());
System.out.printf("Please enter the longitude :");
this.longitude = Float.parseFloat(input.nextLine());
if (days > 0) {
this.rainRecorded = new int[this.days];
}
}
private void gaugeDetails() {
if (this.days > 0) {
System.out.printf("%-9s %-3s %s \n", this.message1, this.message6, this.site);
System.out.printf("%s %-3s % 09.4f\n", this.message2, this.message6, this.lattitude);
System.out.printf("%s %-3s %9.4f\n", this.message3, this.message6, this.longitude);
System.out.printf("%-9s %-3s %-2d%s \n", this.message4, this.message6, this.days, this.message5);
}
}
private void displayHistogram() {
for (int amount : rainRecorded) {
for (int count = 0; count < amount; count++) {
System.out.print("*");
}
System.out.println(" " + amount);
}
}
public static void main(String[] args) {
#SuppressWarnings("unused")
RainRecording objName;
objName = new RainRecording();
}
}
Now, if rainEntered is suppose to be some kind of compounding array, where it allows you to record multiple days of rain over different periods, you might consider using a multi-dimensional array instead, so you could n periods and each period could have n days of rain...

I had error in Department constructor in if else in dept function

I had an error in the Department constructor in the if else statement in dept() method. How can I solve this?
I tried several tries by making the function abstract using different function name but it doesn't work.
class Book
import java.util.*;
class Book
{
int Book_id;
String Book_Name;
String Author_Name;
int pages;
float prices;
void getbook()
{
Scanner SC=new Scanner(System.in);
System.out.println("Enter the Book ID");
Book_id=SC.nextInt();
System.out.println("Enter the Book Name");
Book_Name=SC.next();
System.out.println("Enter the Author Name");
Author_Name=SC.next();
System.out.println("Enter the pages");
pages=SC.nextInt();
System.out.println("Enter the prices");
prices=SC.nextFloat();
}
void display()
{
System.out.println("Book Id"+Book_id);
System.out.println("Book Name"+Book_Name);
System.out.println("Author Name"+Author_Name);
System.out.println("Pages"+pages);
System.out.println("Prices"+prices);
}
}
class Student
class Student extends Book
{
String Student_N;
int roll_no;
}
class Department
class Department extends Student
{
int choice;
String Dept_Code;
Department(int roll,String C)
{
System.out.println(""+C+""+roll_no);
}
void dept()
{
Scanner SC=new Scanner(System.in);
System.out.println("1.Civil Enginerring");
System.out.println("2.Computer Enginerring");
System.out.println("3.Information Tecnology");
System.out.println("4.Mechanical Engineering");
System.out.println("5.Electorics Enginerring");
System.out.println("6.Electrical Enginerring");
System.out.println("Enter the choice");
choice=SC.nextInt();
switch (choice)
{
case 1:
dept_data();
break;
case 2:
dept_data();
break;
case 3:
dept_data();
break;
case 4:
dept_data();
break;
case 5:
dept_data();
break;
case 6:
dept_data();
break;
}
}
void dept_data()
{
Scanner SC=new Scanner(System.in);
System.out.println("Enter the Student Details");
System.out.println("Enter the Student Name");
SC.next();
System.out.println("Enter the Student Roll No");
SC.nextInt();
System.out.println("Enter the Book ID");
SC.nextInt();
System.out.println("Enter the Book Name");
SC.next();
}
int dept_del(String C)
{
Scanner SC=new Scanner(System.in);
if(C.compareTo("ci")==0||C.compareTo("CI")==0)
{
System.out.println("Enter the roll no");
roll_no=SC.nextInt();
Department(roll_no,C); //error
}
else if(C.compareTo("IT")==0||C.compareTo("it")==0)
{
System.out.println("Enter the roll no");
roll_no=SC.nextInt();
Department(roll_no,C); //error
}
else if(C.compareTo("CO")==0||C.compareTo("co")==0)
{
System.out.println("Enter the roll no");
roll_no=SC.nextInt();
Department(roll_no,C); //error
}
else if(C.compareTo("ME")==0||C.compareTo("me")==0)
{
System.out.println("Enter the roll no");
roll_no=SC.nextInt();
Department(roll_no,C); //error
}
else if(C.compareTo("EC")==0||C.compareTo("ec")==0)
{
System.out.println("Enter the roll no");
roll_no=SC.nextInt();
Department(roll_no,C); //error
}
else if(C.compareTo("EE")==0||C.compareTo("ee")==0)
{
System.out.println("Enter the roll no");
roll_no=SC.nextInt();
Department(roll_no,C); //error
}
}
}
class Project
class Project
{
public static void main(String[] args)
{
int i=1,flag=0;
Department A[]=new Department[100];
Scanner SC=new Scanner(System.in);
System.out.println("Enter the Choice");
System.out.println("1.Add a Book\n2.Display the Book");
while(flag==0)
{
int choice=SC.nextInt();
switch (choice)
{
case 1 :
A[i].getbook();
i++;
case 2:
int n=i;
for(i=0;i<n;i++)
A[i].display();
case 3:
flag=1;
break;
default:
System.out.println("Wrong Choice");
}
}
}
}

The problem in your constructor is that it receives int roll, String C and does nothig with them and the instance vars int choice& String Dept_Codeare not defined after the constructor executes.
Maybe you wanted to do:
Department(int choice, String Dept_Code) {
this.choice = choice;
this.Dept_Code = Dept_Code;
System.out.println("" + Dept_Code + " - " + choice);
}
In the switch(choice) some breaks are missing after case 1 & 2 if you want to separate add a book fom display the book and from case 3:
switch(choice) {
case 1 :
A[i].getbook();
i++;
break;
case 2:
int n=i;
for(i=0;i<n;i++)
A[i].display();
break;
case 3:
flag=1;
break;
default:
System.out.println("Wrong Choice");
}
And in the other switch it makes no sense to create a switch if all the cases just execute the same dept_data()
code.
And as a suggestion it's better to always use the constant first when comparing to prevent from possible null pointers:
"ci".compareTo(C) is better than C.compareTo("ci") as the second option could throw a null pointer exception if C is undefined. Also, have a look at naming conventions: https://www.geeksforgeeks.org/java-naming-conventions/

Use switch case within while loop

I'm trying to code simple calculator (all in one) using Switch cases in java. I came up with following code so far. However I'm stuck with while loop. I want to keep showing main menu after each case execution until user decides to exit the program.
public static void main(String[] args)
{
Scanner s=new Scanner(System.in);
System.out.println("Main Menu:");
System.out.println("1. Addition");
System.out.println("2. Substraction");
System.out.println("3. Multipication");
System.out.println("4. Division");
System.out.println("Enter your choice: ");
int i=s.nextInt();
System.out.println("ENTER FIRST NUMBER ");
int a=s.nextInt();
System.out.println("ENTER SECOND NUMBER ");
int b=s.nextInt();
int result=0;
switch(i)
{
case 1:
result=a+b;
break;
case 2:
result=a-b;
break;
case 3:
result=a*b;
break;
case 4:
result=a/b;
break;
default:
System.out.println("Wrong Choice.");
}
System.out.println("Answer is "+result);
}
}
Above code works fine. Program ends itself after execution of user selected choice. I want to put main menu on a repeat.

Add a while loop like this:
public static void main(String[] args) {
// Moved this outside the while loop as davidxxx pointed out +1
Scanner s = new Scanner(System.in);
while (true) {
System.out.println("Main Menu:");
System.out.println("1. Addition");
System.out.println("2. Substraction");
System.out.println("3. Multipication");
System.out.println("4. Division");
System.out.println("Enter your choice: ");
int i = s.nextInt();
System.out.println("ENTER FIRST NUMBER ");
int a = s.nextInt();
System.out.println("ENTER SECOND NUMBER ");
int b = s.nextInt();
int result = 0;//'result' will store the result of operation
switch (i) {
case 1:
result = a + b;
break;
case 2:
result = a - b;
break;
case 3:
result = a * b;
break;
case 4:
result = a / b;
break;
default:
System.out.println("Wrong Choice.");
}
System.out.println("Answer is " + result);
System.out.println("Go again?");
String goAgain = s.next();
if (!goAgain.equals("y")) {
break;
}
}
}

Try this:
import java.util.Scanner;
public class Calculator {
private static final String EXIT = "EXIT";
public static void main(String[] args) {
Calculator calc = new Calculator();
Scanner s = new Scanner(System.in);
while (true) {
String res = calc.runCalc(s);
if (res.equals(EXIT)) {
break;
} else {
System.out.println(res);
}
}
}
private String runCalc(Scanner s) {
System.out.println("Main Menu:");
System.out.println("1. Addition");
System.out.println("2. Substraction");
System.out.println("3. Multipication");
System.out.println("4. Division");
System.out.println("5. Exit");
System.out.println("Enter your choice: ");
int i = s.nextInt();
if (i == 5) {
return EXIT;
}
System.out.println("ENTER FIRST NUMBER ");
int a = s.nextInt();
System.out.println("ENTER SECOND NUMBER ");
int b = s.nextInt();
int result = 0;// 'result' will store the result of operation
switch (i) {
case 1:
result = a + b;
break;
case 2:
result = a - b;
break;
case 3:
result = a * b;
break;
case 4:
result = a / b;
break;
default:
return "Wrong Choice.";
}
return "Answer is " + result;
}
}

There is more than one way to achieve this, you can use
while loop.
do-while loop.
for loop.
I think do-while loop is better for your situation. Because either user wants to continue or not you have to proceed one time(before loop false). And you do not want to use another variable for quit the loop.
public static void main(String[] args)
{
Scanner s=new Scanner(System.in);
int result=0;
do{
System.out.println("Main Menu:");
System.out.println("-1. complete and calculate");
System.out.println("1. Addition");
System.out.println("2. Substraction");
System.out.println("3. Multipication");
System.out.println("4. Division");
System.out.println("Enter your choice: ");
int i=s.nextInt();
if(i ==-1){
System.out.println("Answer is "+result);
return;
}
System.out.println("ENTER FIRST NUMBER ");
int a=s.nextInt();
System.out.println("ENTER SECOND NUMBER ");
int b=s.nextInt();
switch(i)
{
case 1:
result=a+b;
break;
case 2:
result=a-b;
break;
case 3:
result=a*b;
break;
case 4:
result=a/b;
break;
default:
System.out.println("Wrong Choice.");
break;
}
}while(true);
}

switch case in implementation of stack using array in java

import java.io.*;
import java.util.*;
public class Stack1{
static final int MAX=100;
int top=-1;
int[] stack=new int[MAX];
public static void main(String args[])
{
Stack1 s1=new Stack1();
int opt, val;
System.out.println("1. PUSH ");
System.out.println("2. POP ");
System.out.println("3. PEEP ");
System.out.println("4. DISPLAY STACK ");
System.out.println("5. EXIT ");
System.out.println("\n Enter Your Option: ");
Scanner s=new Scanner(System.in);
opt=s.nextInt();
do{
switch(opt)
{
case 1: System.out.println("Enter the value to be added to the stack: ");
val=s.nextInt();
s1.push(val);
break;
case 2: s1.pop();
break;
/*
case 3: s1.peep();
break; */
case 4: s1.display();
break;
}
}while(opt!=5);
}
public void push(int val)
{
if(top==MAX-1)
{
System.out.println("Stack is FULL!");
}
else
{
top++;
stack[top]=val;
System.out.println("Element added to the stack is: "+val);
display();
}
}
public void pop()
{
int x;
if(top==-1)
{
System.out.println("Stack is EMPTY!");
}
else
{
x=stack[top];
System.out.println("The element deleted from the stack is: "+x);
top--;
display();
}
}
public void peep()
{
int n;
n=stack[top];
System.out.println("The value at the top of the stack is: "+n);
}
public void display()
{
int i;
if(top==-1)
System.out.println("STACK IS EMPTY!");
else
{
for(i=0; i<=top; i++)
System.out.println("The elements in the stack are: "+stack[i]);
}
}
}
I wrote this java code to implement stack. But once I select any option, only that method gets executed and the program ends. I want the program to provide me to enter another option once the current method is executed. What should I do?

As #LordWilmore pointed out in his comment, the opt value will be set just once causing program to spin forever in a corresponding case (unless the value is 5). Moving opt = s.nextInt(); inside loop will fix the issue.
do {
System.out.println("Enter Your Option: ");
opt = s.nextInt();
switch(opt) {
//...
}
} while (opt != 5);

You can modify your main method in a manner like this:
public static void main(String args[]){
int option;
Scanner sc = new Scanner(System.in);
MyStack1 s = new MyStack1();
while(true){
System.out.println("Enter the choice You want to perform on the stack: ");
System.out.println(" 1. push \n 2. Pop \n 3. Display \n 4. peep \n 5. Exit");
System.out.println("Enter your option: ");
option = sc.nextInt();
switch(option){
case 1: System.out.println("Enter the element you want to push into the stack: ");
s.push(sc.nextInt());
break;
case 2: s.pop();
break;
case 3: System.out.println("Displaying the stack contents: ");
s.display();
break;
case 4: System.out.println("The top element in the stack is: ");
s.peek();
break;
case 5: System.out.println("You selected Exit!!");
break;
default: System.out.println("Wrong choice!! Please enter a valid option!!");
return;
}
}
}

Need assistence displaying value from a different private class

Okay, first off I am very, very new to java. For this project I need to design a program that takes a product number, an amoutn sold, calculates the total, and then displays it. However, I need to to display when I select option 2, which is a seperate private class, to be honest I don't even know where to begin. Any help would be appreciated.
import java.util.Scanner;
public class Attempt1
{
//method to pause until a key is pressed
public static void pause()
{
try
{
System.out.print("Press <Enter> to continue...");
System.in.read();
}
catch (Exception e)
{
System.err.printf("Error %s%c\n",e.getMessage(),7);
}
}//end pause
public static void main(String[] args)
{
//variables to capture keyboard input
Scanner keyBd = new Scanner( System.in );
char selection;
//int selection;
do{//display menu
System.out.println("\n--------------");
System.out.println("Retail Sales\n");
System.out.println("1. Enter Products Sold");
System.out.println("2. Display Total Retail Sales");
System.out.println("3. Exit\n");
System.out.print ("Selection: ");
//get menu selection
selection = keyBd.next().charAt(0);
//selection = keyBd.nextInt();
//process menu selection
switch (selection){
case '1':
enterProducts();
break;
case '2':
displaySales();
break;
case '3':
//recognize as valid selection but do nothing
break;
default :
//System.out.printf("%c\n",7);
System.out.println("Invalid Selection");
}//end switch
}while( selection != '3');
}//end main()
private static void enterProducts()
{
Scanner inp = new Scanner(System.in);
int product,quantity;
double total = 0.00;
System.out.print("Enter product #(1-5)(0 to stop): ");
product=inp.nextInt();
while(product !=0)
{
System.out.print("Enter quantity: ");
quantity=inp.nextInt();
switch( product ){
case 1:total+=quantity*2.98;
break;
case 2:total+=quantity*4.50;
break;
case 3:total+=quantity*3.98;
break;
case 4:total+=quantity*4.49;
break;
case 5:total+=quantity*6.87;
break;
default:System.out.println("Invalid Product Number");
System.out.println("Product Number Does not Exist");
if(product<0 && product>=6)
{
System.out.print("Enter product #(1-5)(0 to stop): ");
product=inp.nextInt();
System.out.print("Enter quantity: ");
quantity=inp.nextInt();
}
break;
}
System.out.print("Enter product #(1-5)(0 to stop): ");
product=inp.nextInt();
}
pause();
}
private static void displaySales()
{
System.out.println( "The total retail value was: " + total );
pause();
}
}//end MenuDemo

Here is an algorithm for improving your code:
At the beginning of your your main add a variable total and initialize it with 0: double total=0;
Change the enterProducts method's return type to double: private static double enterProducts() and return the local variable total at the end from this method after the call to pause: return total;
In the case for the input of 1 add the returned value from enterProducts to the current value of total (it's the total inside your main): total += enterProducts();
Add to the method displaySales an double argument: private static void displaySales(double total) and change the call to it in the main's case for 2 to displaySales(total);

I think you mean private method. You could pass the total like so:
private static void displaySales(double total) {
...
total is defined in enterProducts but not in the main method where the loop is displayed, so you could return this:
double enterProducts() {
...
return total;
}
so that you can pass it to displaySales.

The problem with the code is that you're trying to access a local variable, declared in the static enterProducts() method, inside of the static displaySales() method.
The code below solves that "problem".
With that being said, I recommend that you work through some Java tutorials to understand why the code now works... Have a look at Variable Scope.
public class Attempt1
{
//use a static variable to store the total
static double total = 0.00;
//method to pause until a key is pressed
public static void pause()
{
try
{
System.out.print("Press <Enter> to continue...");
System.in.read();
}
catch (Exception e)
{
System.err.printf("Error %s%c\n",e.getMessage(),7);
}
}//end pause
public static void main(String[] args)
{
//variables to capture keyboard input
Scanner keyBd = new Scanner( System.in );
char selection;
//int selection;
do{//display menu
System.out.println("\n--------------");
System.out.println("Retail Sales\n");
System.out.println("1. Enter Products Sold");
System.out.println("2. Display Total Retail Sales");
System.out.println("3. Exit\n");
System.out.print ("Selection: ");
//get menu selection
selection = keyBd.next().charAt(0);
//selection = keyBd.nextInt();
//process menu selection
switch (selection){
case '1':
enterProducts();
break;
case '2':
displaySales();
break;
case '3':
//recognize as valid selection but do nothing
break;
default :
//System.out.printf("%c\n",7);
System.out.println("Invalid Selection");
}//end switch
}while( selection != '3');
}//end main()
private static void enterProducts()
{
Scanner inp = new Scanner(System.in);
int product,quantity;
System.out.print("Enter product #(1-5)(0 to stop): ");
product=inp.nextInt();
while(product !=0)
{
System.out.print("Enter quantity: ");
quantity=inp.nextInt();
switch( product ){
case 1:total+=quantity*2.98;
break;
case 2:total+=quantity*4.50;
break;
case 3:total+=quantity*3.98;
break;
case 4:total+=quantity*4.49;
break;
case 5:total+=quantity*6.87;
break;
default:System.out.println("Invalid Product Number");
System.out.println("Product Number Does not Exist");
if(product<0 && product>=6)
{
System.out.print("Enter product #(1-5)(0 to stop): ");
product=inp.nextInt();
System.out.print("Enter quantity: ");
quantity=inp.nextInt();
}
break;
}
System.out.print("Enter product #(1-5)(0 to stop): ");
product=inp.nextInt();
}
pause();
}
private static void displaySales()
{
System.out.println( "The total retail value was: " + total );
pause();
}
}//end MenuDemo