Need help implenting arrays and method call into existing code

Code :

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import java.util.*;
import java.text.*;
 
 
public class Interest {
    static DecimalFormat fmt=new DecimalFormat("0.00"); //2 decimal place.
    static Scanner input=new Scanner(System.in).useDelimiter("\r\n");
    static double[] principle = new double [10];
    static double[] rate      = new double [10];
    static double[] interest  = new double [10];
    static double[] days      = new double [10];
    static int i;
    static int choice;
 
    public Interest() {
    }
 
 
    public static void main(String[] args) {
 
 
     do
{
            System.out.println(" Interest Calculation ");
	System.out.println(" ---------------------");
	System.out.println("1. Calculate interest payable");
	System.out.println("2. Calculate principle required to earn $x of interest");
	System.out.println("3. Calculate time required to earn $x of interest");
	System.out.println("4. Exit program");
	System.out.println(" ");
	System.out.print("Please select your choice (1-4):");
	choice = input.nextInt();
	System.out.println("---------------------------------");
	    	switch(choice)		
 
{	
	case 1 :	 //Caluclate interest
 
 
 
	System.out.print("Enter principle amount in $ :");
	principle[i]=input.nextInt();
	System.out.print("Enter interest rate in % :");
	rate[i]=input.nextDouble();
	System.out.print("Enter period(time) in days :");
	days[i]=input.nextInt();
	System.out.println("Interest earned for principle of $" + principle[i]+" at interest rate of " +rate[i]+ "% is $" + interest[i]);
	 System.out.println(" ");
	interest[i] = principle[i] * ((rate[i]/100)*(days[i]/365));
 
	break;	
 
 
 
	case 2 :  // Calculate principle
	System.out.print("Enter interest amount to be earned in $ :");
	interest[i]=input.nextDouble();
	System.out.print("Enter interest rate in % :");
	rate[i]=input.nextInt();
	System.out.print("Enter period(time) in days :");
	days[i]=input.nextInt();
	principle[i] = interest[i] / (days[i]/365/rate[i]/100) ; 
	System.out.println("To earn an interest of " +interest[i]+ ", over a period of " +days[i]+ "days, you need a principle of " +principle[i]);
	System.out.println(" ");		 
	break;
 
	case 3 :  // Calculate days
 
	System.out.print("Enter interest amount to be earned in $:");
	interest[i]=input.nextDouble();
	System.out.print("Enter interest rate in % :");
	rate[i]=input.nextDouble();
	System.out.print("Enter principle amount in $:");
	principle[i]=input.nextInt();
	days[i] = interest[i] / ( principle[i] * rate[i]/100 ); 
	System.out.println("To earn an interest of $" +interest[i]+ ", with a principle of $"+principle[i]+ " time required is " +days[i]+ " days");
	System.out.println(" ");
	break;
 
 
	case 4 : //show entries displayed
	System.out.println("Thank you for using Interest Calculator"); 
	System.out.println(" ");
	break;
 
 
	default : System.out.println("Please enter 1, 2 or 3");
	System.out.println(" ");
 
            }//end switch
             }while (choice!=4);
              }   
                }

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The question is required to display what the user has entered(principle, rate, days,total and interest) when choice 4 is selected. Also, method call is required. The current code is working(loops, choice). Just do not know how to use arrays and method call, any help would be greatly appreciated