parallel arrays in java

[javanerd123]

Ques: How to get and display the student with the least monthly savings? My coding gives me the least monthly savings but with the incorrect student names.
Please kindly advise how to fix the error.

public class monthlySavings
{
    
    public static void main(String[] args)
    {
       
       String[] studentNames = new String[5];
       double[] monthlySavings = new double[5];
       
       
       getUserInput(studentNames,monthlySavings);
       
       System.out.println("***********************************************");
       
       
       getMinMonthlySavings(studentNames,monthlySavings);
       
   
    }
    
   
    public static void getUserInput(String[] studentNames, double[] monthlySavings)
    {
        
        Scanner console = new Scanner(System.in);
       
        try
        {
            
            for(int i=0; i<studentNames.length; i++)
            {
                System.out.print("Enter the student names: ");
                studentNames[i] = console.next();
                
                System.out.print("Enter the monthly savings: ");
                monthlySavings[i] = console.nextDouble();

            }
        }
        catch(InputMismatchException inputMismatchException)
        {
            System.out.println("Invalid input. Please try again.");
                
            console.nextLine();
        }
        
    }
    
 
    public static void getMinMonthlySavings(String[] studentNames,double[] monthlySavings)
    {
        NumberFormat money = NumberFormat.getCurrencyInstance();
        double minValue = monthlySavings[0];
        String studNames = studentNames[0];
        
        //get each student names
        for(int j=0; j<studentNames.length; j++)
        {   
            
            //get each monthly savings
            for(int i=0; i<monthlySavings.length; i++)
            {
                //to determine the least monthly savings amount
                if(monthlySavings[i] < minValue)
                {
                    studNames = studentNames[j];
                    minValue = monthlySavings[i];  
                } 
                
            }
        }
        
    
        System.out.printf("Student " + studNames + " has the least monthly savings of " + money.format(minValue) + "%n");
        
    }

[pbrockway2]

Hi javanerd123, welcome to the forums!

When you post code, use the "code" tags. You put [code] at the start of the code and [/code] at the end: that way the code will be readable when it appears here.

[pbrockway2]

//get each student names
for(int j=0; j<studentNames.length; j++)
{   
            
    //get each monthly savings
    for(int i=0; i<monthlySavings.length; i++)
        {

By nesting two for loops like this you end up looking at quite a few things. If there are 5 students involved then the comparison "if(monthlySavings[i] < minValue)" will be evaluated 25 times. Write down 5 names and numbers and find the name associated with the lowest number. Do you need to make 25 comparisons, or only 5? Hint: you only look at the numbers once each, and you make only 5 comparisons. Your code should do the same.

[rhexis]

Basically, the way your code is running is like that

Lets say I have 3 names and 3 savings


Jojo
Bobo
Toto

50
10
20

CURRENT STUDENT NAME: JOJO
CURRENT MIN SAVING: 50

1ST NAME LOOP
it will first run through JOJO

1ST SAVING LOOP
check if 50 < 50
FALSE!!!!

i++
check if 10 < 50
TRUE!!!
MINIMUM SAVING = 10
CURRENT STUDENT NAME = j (WHICH IS STILL 0 BECAUSE IT HAS NOT GONE OUT OF THE 2ND FOR LOOP)

i++
check if 10 < 20
FALSE!!!!!

finish 2nd for loop

goes back to 1st for loop.

2ND NAME LOOP
J=1

DOES NOTHING

2ND MIN SAVING LOOP

check if 10 < 50
FALSE!!!!

i++
check if 10 < 10
FALSE!!!

i++
check if 10 < 20
FALSE!!!!!

COMPLETES 2ND MIN SAVING LOOP

3RD NAME LOOP
j=2

DOES NOTHING

3RD MIN SAVING LOOP
J=3
check if 10 < 50
FALSE!!!!

i++
check if 10 < 10
FALSE!!!

i++
check if 10 < 20
FALSE!!!!!



So basically your student name will always be stuck at [0] because j will always be 0 when it enters the 2nd for loop, and it will never enter the 2nd for loop again. Hope I explained it well enough.The code is simple, so try to figure it out with the logic I've given. Hopefully it will help you in future for loops as well.


EDIT: ninja'd. Spent too much time typing.

[JosAH]

Parallel arrays beg for a small data class:

public class Student {
   public String name;
   public double savings;
}

Now the name and savings are tightly coupled. Build an array of Sudent records and you're in business.

kind regards,

Jos