使用两个循环，但只有一个循环运行。 计算机科学导论（Java）

Question

So I am trying to create a simple stock program. My first loop works but, it won't pass to my second one and I can't figure out why. I've tried breaks and if statements and I can't figure it out.

days = JOptionPane.showInputDialog("Enter the number of days in the stock period"); //Allows user to enter value
sharePoints = JOptionPane.showInputDialog("Enter the share points on the first day");   
int daynum = Integer.parseInt(days);
int share = Integer.parseInt(sharePoints);

int dayStart = 1;
double daynumMidPoint = (daynum/2);
System.out.println(share);
Math.round(daynumMidPoint);

for(int i = dayStart;i<daynumMidPoint;i++) {
    System.out.println(share=share+50);
}

for(int l = dayStart;l>=daynumMidPoint;l++){
    System.out.println(share=share-25);
}

Answer 1

Well if the first loop works, the second one will not since the first loop will only start if dayStart is under daynumMidPoint and the second one will only start dayStart is above or equal to daynumMidPoint .

If the first one succeeds then the second one definitely will not.

Answer 2

Your math is wrong and the condition for the second loop is not fulfilled

int dayStart = 1;
double daynumMidPoint = (daynum/2); // daynum = 10 ---> daynumMidPoint = 5
System.out.println(share);
Math.round(daynumMidPoint);

for(int i = dayStart;i<daynumMidPoint;i++) // i = 1, Condition: i < 5 = true
{
    System.out.println(share=share+50);
}
for(int l = dayStart;l>=daynumMidPoint;l++) // l = 1, Condition l >= 6 = false
{
    System.out.println(share=share-25);
}

So to fix this issue, you either need to adjust the condition for the second for loop. Or you need to set l to a different start value.

Answer 3

Showing that this

int dayStart = 1;

is set to one, this other loop wont work:

for(int l = dayStart;l>=daynumMidPoint;l++){
System.out.println(share=share-25);

since l is set to 1 and for the loop to run, you need l to be BIGGER or EQUAL than daynumMidPoint , and since this is set to double daynumMidPoint = (daynum/2); then it wont run since its bigger than l .

Seeing also that it seems you want Shares to increase if the current day is below the midpoint and decrease if the current day is above the midpoint, you can just put this(or something like this):

if(i<daynumMidPoint){
SOP(share=share+50);} 
else{
SOP(share=share-25);
}

inside this for-loop :

for(int i = dayStart;i<daynumMidPoint;i++) {

}