Develop Reference

converting from if-else to methods

Here is my current code:
import java.util.Scanner;//importing scanner
public class QuestionOne {
public static void main(String[] args) {
int numberofDays;//these two lines define variables
int sharePoints;
Scanner keyboard = new Scanner(System.in);//activating scanner
System.out.print("Number of days in the period: ");//asking question
numberofDays = keyboard.nextInt();//obtaining input by defining a variable as a keyboard input
System.out.print("Share points on the first day: ");//asking another question
sharePoints = keyboard.nextInt();//obtaining input by defining a variable as a keyboard input
while (numberofDays < 10 || numberofDays > 20)//while loop makes sure the conditions stay true
{
System.out.println("The number of days doesn’t meet the required criteria, enter it again");
System.out.print("Number of days in the period: ");
numberofDays = keyboard.nextInt();
//above three lines ask for number of days until a value that fits within specification is obtained
}
System.out.println("Day " + " Share Points");
System.out.println(1 + " " + sharePoints);
//above two lines print day and share points, as well as the first line of text (as it does not change)
for (int i = 2; i <= numberofDays; i++) {
if (numberofDays % 2 == 0)
if (i <= numberofDays / 2) {
sharePoints = sharePoints + 50;
System.out.println(i + " " + sharePoints);
} else {
sharePoints = sharePoints - 25;
System.out.println(i + " " + sharePoints);
} else {
if (i <= numberofDays / 2 + 1) {
sharePoints = sharePoints + 50;
System.out.println(i + " " + sharePoints);
} else {
sharePoints = sharePoints - 25;
System.out.println(i + " " + sharePoints);
// above nested if else statements essentially calculate and concatenate the variables to obtain an answer that is then printed and repeated until the number of days is reached (starting from day two)
}
}
}
}
}
This code compiles and works as I want, however, I no longer want it to be in this format. Instead, I would like for it to contain a method named DisplayStock; the input arguments I want for this method are the
number of days in the period and the share points on the first day. The method is used to increase the share points by 50 and decrease the share points by 25 on alternate days in the specified period. The method then
displays a table showing the days and the share points on those days. This method doesn’t return anything.
As for the main method, it will first ask the users to enter the number of days in the specified period and the share points on the first day (with input validation, the program should then call the DisplayStock method that outputs the table.
A sample output currently looks as such if the period is ll days and SharePoint are 550:
Day Share Points
1 550
2 600
3 575
4 625
5 600
6 650
7 625
8 675
9 650
10 700
11 675
So basically, what I am intending to do is convert the code from if-else statements over to methods to alleviate issues with readability and function. Any help would be appreciated! I will continue to work on this but I do not think I will be able to get as far as I intend.

you just want to break the code in to two methods or several
basic will be this:
public static void main(String[] args) {
int numberofDays;//these two lines define variables
int sharePoints;
Scanner keyboard = new Scanner(System.in);//activating scanner
System.out.print("Number of days in the period: ");//asking question
numberofDays = keyboard.nextInt();//obtaining input by defining a variable as a keyboard input
System.out.print("Share points on the first day: ");//asking another question
sharePoints = keyboard.nextInt();//obtaining input by defining a variable as a keyboard input
numberofDays = validator(numberofDays,keyboard); // Validates Keyboard input
//above two lines print day and share points, as well as the first line of text (as it does not change)
outPutTablePrinter(numberofDays,sharePoints);
}
private static void outPutTablePrinter(int numberOfDays,int sharePoints){
System.out.println("Day " + " Share Points");
System.out.println(1 + " " + sharePoints);
for (int i = 2; i <= numberOfDays; i++) {
if (numberOfDays % 2 == 0)
if (i <= numberOfDays / 2) {
sharePoints = sharePoints + 50;
System.out.println(i + " " + sharePoints);
} else {
sharePoints = sharePoints - 25;
System.out.println(i + " " + sharePoints);
} else {
if (i <= numberOfDays / 2 + 1) {
sharePoints = sharePoints + 50;
System.out.println(i + " " + sharePoints);
} else {
sharePoints = sharePoints - 25;
System.out.println(i + " " + sharePoints);
// above nested if else statements essentially calculate and concatenate the variables to obtain an answer that is then printed and repeated until the number of days is reached (starting from day two)
}
}
}
}
private static int validator(int numberOfDays,Scanner keyboard){
while (numberOfDays < 10 || numberOfDays > 20)//while loop makes sure the conditions stay true
{
System.out.println("The number of days doesn’t meet the required criteria, enter it again");
System.out.print("Number of days in the period: ");
numberOfDays = keyboard.nextInt();
}
return numberOfDays;
}

I refactored your code. First, I would prefer printf and your logic can be greatly simplified by incrementing by two in your loop. You do need to check if there is an index + 1 for it to work correctly with odd number of days, but you can do
System.out.printf("Day\tShare Points%n");
for (int i = 0; i < numberofDays; i += 2) {
System.out.printf("%-3d\t%d%n", i + 1, sharePoints);
sharePoints += 50;
if (i + 1 < numberofDays) {
System.out.printf("%-3d\t%d%n", i + 2, sharePoints);
sharePoints -= 25;
}
}
And I get
Day Share Points
1 550
2 600
3 575
4 625
5 600
6 650
7 625
8 675
9 650
10 700
11 675

Following code be used:
import java.util.Scanner;//importing scanner
public class QuestionOne{
static int numberofDays;//these two lines define variables
static int sharePoints;
public static void main(String[]args){
Scanner keyboard = new Scanner (System.in);//activating scanner
System.out.print("Number of days in the period: ");//asking question
numberofDays = keyboard.nextInt();//obtaining input by defining a variable as a keyboard input
System.out.print("Share points on the first day: ");//asking another question
sharePoints = keyboard.nextInt();//obtaining input by defining a variable as a keyboard input
while (numberofDays < 10 || numberofDays > 20)//while loop makes sure the conditions stay true
{
System.out.println("The number of days doesn’t meet the required criteria, enter it again");
System.out.print("Number of days in the period: ");
numberofDays = keyboard.nextInt();
//above three lines ask for number of days until a value that fits within specification is obtained
}
DisplayStock ();
}
public static void DisplayStock (){
System.out.println("Day " + " Share Points");
System.out.println(1 + " " + sharePoints);
//above two lines print day and share points, as well as the first line of text (as it does not change)
for(int i = 2; i <= numberofDays; i++)
{
if(numberofDays % 2 == 0)
if(i <= numberofDays/2)
{
sharePoints = sharePoints + 50;
System.out.println(i + " " + sharePoints);
}
else
{
sharePoints = sharePoints - 25;
System.out.println(i + " " + sharePoints);
}
else
{
if(i <= numberofDays/2 + 1)
{
sharePoints = sharePoints + 50;
System.out.println(i + " " + sharePoints);
}
else
{
sharePoints = sharePoints - 25;
System.out.println(i + " " + sharePoints);
//above nested if else statements essentially calculate and concatenate the variables to obtain an answer that is then printed and repeated until the number of days is reached (starting from day two)
}
}
}
}
}

Finding middle of user input (int) and increasing/decreasing half of the values in JAVA

Im trying to implement a program in Java that a user inputs a number greater than 10 & another number (whatever number) then it will list whatever first number the user inputs for example if it was 11 then it'd print 1-11 with corresponding numbers in which it increases by 50 in the first half (1-6) and decreases 25 for the rest (7-11). I have the following code but im having trouble trying to figure out the logic/how to go about the values being increased/decreased.
again the output would be something like this:
1 550
2 600
3 650
4 700
5 750
6 800
7 775
8 750
9 725
10 700
11 675
import java.util.Scanner;
public class Periods2
{
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
System.out.print("enter the number of days in a given period:");
int numbers = 1;
int number = Integer.parseInt(reader.nextLine());
if(number < 10){
System.out.print("the number of days doesnt meet the required criteria enter it again:");
number = reader.nextInt();
}
System.out.print("enter the number of sharepoints:");
int sharepoints = Integer.parseInt(reader.nextLine());
while (numbers <= number && sharepoints > number){
System.out.println(numbers + " " + sharepoints);
numbers++;
}
}
}

Find the half of your input, and in your loop you can add 50 to sharepoints until the value of numbers reaches half, and then decrease by 25 after that:
int half = (int) Math.ceil(number/2.0);
while (numbers <= number && sharepoints > number){
System.out.println(numbers + " " + sharepoints);
if(numbers < half) {
sharepoints += 50;
}
else {
sharepoints -= 25;
}
numbers++;
}

Make range with only first and last number? Java?

I have to get input for a certain number of days and a starting number. With that, the number of days gets split in half, in first half starting number decremented by 2. Last half incremented by 1. If days is uneven, last half has one more day. Heres what I have:
int days;
int num;
int 1half;
int 2half;
int new_num;
System.out.print("Enter number of days: ");
days = keyboard.nextInt();
System.out.print("Enter number of first day: ");
num = keyboard.nextInt();
int half = days/2;
if (days %2 == 0){
1half = (half);
2half = (half);
} else {
1half = (half);
2half = (half) + 1;
}
int first_half[] = {1,(half)};
int last_half[] = {((half)+1), days};
while (1half > 1 || 1half < half) {
new_temp = temp - 2;
System.out.println("Day \t Num");
System.out.println(new_num);
first_half--;
}
while(2half >= (half + 1) && (2half <= days)) {
new_temp = temp++;
System.out.println("Day \t Num");
System.out.println(new_num);
last_half--;
}
Im stuck now though.
If you see anything Id be happy to hear about it. I just need some help/advice. I'll clarify anything if this is hard to understand. Thank you in advance
Edit:
The final output should look something like this:
Day Num
1 -10
2 -12
3 -14
4 -16
5 -18
6 -17
7 -16
8 -15
9 -14
10 -13
11 -12
If this makes sense.
Heres my output:
Day Temperature
8
Day Temperature
8
Day Temperature
8
Day Temperature
continues forever

I don't know why do you need those arrays and other stuff, but you may have a look at my code. It produces exactly what you want.
int days = 11;
int num = -10;
int output = num + 2;
System.out.println("Day \t Num");
int half = days / 2;
for (int i = 1; i <= half; i++) {
output -= 2;
System.out.println(i + "\t" + output);
}
for (int i = half + 1; i <= days; i++) {
output++;
System.out.println(i + "\t" + output);
}

Your endless loop is caused by your condition statement of your while:
while (1half > 1 || 1half < half).
If 1half is set to be any number greater than 1 then this will loop forever. You probably want to use an && instead of an || as well. But don't see anything in the body of the loop that would affect things to make it get out of the loop.

how would I find the nth term in a loop? java

Here is a quick look at the program that I made to give a better example of my question.
Loop code
public void scheme1(int d) {
// first modification
if (mark<=20){
System.out.print("\nBecause mark under 20 mark stays as its original value. mark="+mark);
return;
}
int total = mark;
int finalMark=20;
System.out.print("Scheme 1"+"\n");
// Loop
for(int loopParameter = START_CONDITION;
loopParameter <= d;loopParameter++){
System.out.print("(" + loopParameter + ") " + total + " ");
total = total + constantDiffSch1;
// second modification
if (total < 40){
System.out.print("\nThis work can be up to " + loopParameter);
return;
}
// third modification
if (total<=20){
System.out.print("\nBecause mark drops below 20, mark stays as 20. final mark="+ finalMark);
return;
}
} // End
System.out.print("\n\n");
}
This is what my program outputs
Please input mark: 64
Please input number of days to display: 10
Scheme 1
(0) 64 (1) 59 (2) 54 (3) 49 (4) 44
This work can be up to 4 days late before failing.
This is what the output is supposed to be
Please input mark: 64
Please input number of days to display: 10
Scheme 1
(0) 64 (1) 59 (2) 54 (3) 49 (4) 44 (5) 39 (6) 34 (7) 29 (8) 24
This work can be up to 4 days late before failing.
I have to display how many days late the assignment is and calculate the late penaltie (mark -5) I also have to display the number of days needed needed to fail the assigment ( number of days until failure might be larger than the number (d) of days that the user input ) . the failing mark is less than 40.
2nd example (output)
Please input mark: 64
Please input number of days to display: 2
Scheme 1
(0) 64 (1) 59 (2) 54
This work can be up to 4 days late before failing.
I have almost complete my code but this problem is slowing me down.
P.S. I am new at java
here is my full program
LatePenalties calss
public class LatePenalties {
// attributes
private int mark;
private static final int constantDiffSch1 = -5;
private static final double constantDiffSch2 = 0.9;
private static final int START_CONDITION = 0;
// constructors
public LatePenalties(int m) {
mark = m;
}
// methods
public void scheme1(int d) {
// first modification
if (mark<=20){
System.out.print("\nBecause mark under 20 mark stays as its original value. mark="+mark);
return;
}
int total = mark;
int finalMark=20;
System.out.print("Scheme 1"+"\n");
// Loop
for(int loopParameter = START_CONDITION;
loopParameter <= d;loopParameter++){
System.out.print("(" + loopParameter + ") " + total + " ");
total = total + constantDiffSch1;
// second modification
if (total < 40){
System.out.print("\nThis work can be up to " + loopParameter);
return;
}
// third modification
if (total<=20){
System.out.print("\nBecause mark drops below 20, mark stays as 20. final mark="+ finalMark);
return;
}
} // End
System.out.print("\n\n");
}
public void scheme2(int d) {
double total = mark;
System.out.print("\n\nScheme 2"+"\n");
// Loop
for(int loopParameter = START_CONDITION;
loopParameter <= d;loopParameter++){
System.out.print( "(" + loopParameter + ") " );
System.out.printf("%.02f",total);
System.out.print(" ");
total = total * constantDiffSch2;
} // End
System.out.print("\n");
}
}
Main class
import java.util.Scanner;
public class LatePenaltiesUser {
public static void main(String [] args) {
// local variables
Scanner input = new Scanner(System.in);
LatePenalties latePen;
int mark;
int days;
// input
do{
System.out.print("Please input mark (between 0 and 100) --> ");
mark = input.nextInt();
if (( mark < 0 ) | (mark > 100 )){System.out.print("\n" + "Input value outside the range!!!" + "\n");}
}while(( mark < 0 ) | (mark > 100 ));
do{
System.out.print("Please input number of days to display (between 0 and 20) --> ");
days = input.nextInt();
System.out.print("\n");
if (( days < 0 ) | (days > 20 )){System.out.print("Input value outside the range!!!"+ "\n");}
}while(( days < 0 ) | (days > 20 ));
// computation
latePen = new LatePenalties(mark);
latePen.scheme1(days);
latePen.scheme2(days);
}
}
I have to show when the faling mark occurs(at less than 40), but I have to stop the loop at 20 or when the number of days is reached, as I show in the example on what it is expected.

You can use break to come out of the loop as soon as total is less than 40. You can update your scheme1 method as below
public void scheme1(int d) {
int total = mark;
System.out.print("Scheme 1" + "\n");
int days = 0;
// Loop
for (int loopParameter = START_CONDITION; loopParameter <= d; loopParameter++) {
System.out.print("(" + loopParameter + ") " + total + " ");
total = total + constantDiffSch1;
if(total < 40)
break;
days++;
} // End
if (total <= 40) {
System.out.print("\nThis work can be up to " + days +" days late before failing.");
}
System.out.print("\n\n");
}
Please input mark (between 0 and 100) --> 82
Please input number of days to display (between 0 and 20) --> 10
Scheme 1 (0) 82 (1) 77 (2) 72 (3) 67 (4) 62 (5) 57 (6) 52
(7) 47 (8) 42
This work can be up to 8 days late before failing.

You don't need to know your loopParameter to calculate the number of days. You can calculate it like so:
int days = (d - 40) / -constantDiffSch1;
You can use break when you want to quit loop. So:
if (total < 20) break;
And off topic. Don't call loopParameter like that. It is good practice to call it in one symbol (or short word) like i or day. It makes code easier to read and understand.

Guessing game - how to remember the guessing range

I'm trying to make a simple guessing game where computer should guess the number I chose between 0 and 100. Try to run it, press 1 if the number is too low and press 2 if the number is too high.
1.if I choose 50 and computer guesses 41, I press 1 because the number is too low
2.then computer guesses between 41 and 100, say 70, I press 2 because it's too high
3.now the problem is that next the computer should be guessing between 70 and 41 (previously guessed number), but it guesses between 71 and 0, so it's jumping up and down all the time between extremes
4.I don't know how to make it remember the range ie. previously guessed number
System.out.print("Enter a number: ");
Scanner input = new Scanner(System.in);
int num=input.nextInt();
int ans=0;
Random rand = new Random();
int guess=rand.nextInt(100);
while(guess!=num) {
System.out.print("Is it " + guess + " ? ");
ans=input.nextInt();
if (ans==1) {
guess=rand.nextInt(100-guess+1)+guess;
}
else if (ans==2) {
guess=rand.nextInt(100-guess+1)+0;
}
}
System.out.print("Computer guessed: " + guess);
The output looks like this:
Enter a number: 50
Is it 55 ? 2
Is it 26 ? 1
Is it 35 ? 1
Is it 44 ? 1
Is it 54 ? 2
Is it 31 ? 1
Is it 39 ? 1
Is it 87 ? 2
Is it 0 ? 1
Is it 11 ? 1
Is it 97 ? 2

You should use 2 variables: One for upper limit, one for lower limit.
while(guess!=num) {
System.out.print("Is it " + guess + " ? ");
ans=input.nextInt();
if (ans==1) {
lowerLimit = guess; // Your new lower limit .
guess=lowerLimit+ (upperLimit- lowerLimit) * r.nextInt();
}
else if (ans==2) {
upperLimit = guess; // Your new upper limit.
guess=lowerLimit+ (upperLimit- lowerLimit) * r.nextInt();
}
}

This is what you need :
System.out.print("Enter a number: ");
Scanner input = new Scanner(System.in);
int num = input.nextInt();
int ans = 0;
Random rand = new Random();
int min = 0;
int max = 100;
int guess = rand.nextInt(max);
while (guess != num) {
System.out.print("Is it " + guess + " ? ");
ans = input.nextInt();
if (ans == 1) {
min = guess + 1;
} else if (ans == 2) {
max = guess;
}
guess = rand.nextInt(max - min) + min;
}
System.out.print("Computer guessed: " + guess);
sample output:
Enter a number: 50
Is it 62 ? 2
Is it 39 ? 1
Is it 41 ? 1
Is it 56 ? 2
Is it 54 ? 2
Is it 49 ? 1
Is it 52 ? 2
Computer guessed: 50

You need two variables. One for the lower limit and one for the upper limit.