我需要帮助更正我的 blueJ 代码

Question

 import java.util.Scanner;
    /**
     * Write a description of class code here.
     *
     * @author (your name)
     * @version (a version number or a date)
     */
    public class code
    {
        public static void main(String args [])
        {
            {
                docreditcard(); // calls functions
            }
            {
                public static void docreditcard()
            }
            {
                float preb = 0;
                float add = 0;
                float inter = 0;
                float newb = 0;
                float minp = 0;

                preb = getPreviousB();
                add = getAdditional();
                inter = getInterest(preb,add);
                newb = getNewb(preb,add,inter);
                minp = getMinpay(newb);

            }
            public static float getPreviousB()
            {
                Scanner cd = new Scanner(System.in);
                System.out.print("Enter previous balance");
                return cd.nextFloat();
            }
            public static float getAdditional()
            {
                Scanner cd = new Scanner(System.in);
                System.out.print("Enter total new charges");
                return cd.nextFloat();
            }
            public static float getInterest(float preb,float add)
            {
            float interest = 0;
            if(preb == 0)
            {
                interest = 0;
                return interest;
            }
            else
            {
                interest = ( preb + add)*0.020;
                return interest;
            }
        }

        public static float getNewb(float preb,float add,float inter)
        {
            float newbalance = 0;
            newbalance = (preb + add + interest);
            return newbalance;
        }

        public static float getMinpay(float newb)
        {
            float minimal = 0;
            if(newbalance < 50)
            {
                minimal = newbalance;
                return minimal;
            }
            else if( newbalace >= 50 && newbalance <= 300)
            {
                minimal = 50;
                return minimal;
            }
            else
            {
                minimal = (newbalance)*.020;
                return minimal;

            }
        }
        System.out.println("CS International Card  Statement");
        System.out.println("====================\n");
        System.out.println("Previous Balance:\t $%.2f%n",preb);  // prints 
        System.out.println("Additional Charges:\t $%.2f%n",add);  
        System.out.println("Interest:\t\t$%.2f%n",inter);  
        System.out.println("\nNew Balance:\t\t$%.2f%n",newb);  
        System.out.println("Minimum Payment:\t$%.2f%n",minp);  
    }
    }

// 程序应接受用户输入的先前余额和新费用总额。然后应该计算利息，新余额（以前的余额+附加费用+利息）和最低工资。如果先前余额为 0，则利息为 0，否则利息为先前余额的 20% 和额外费用。对于最低工资，如果新余额小于50，则等于最低工资，否则如果在50到300之间，则最低工资为50，如果更高，则最低工资为新余额的20％

Answer 1

我无法为您的程序解决错误，但我能够为它制作自己的版本。

import java.util.Scanner;

类代码 {

public static void main(){
    Scanner sc = new Scanner(System.in);
    System.out.println("enter previous balance and total new charges");
    double pbal = sc.nextDouble();
    double tnc = sc.nextDouble();
    double nbal,interest,mp=0.0;

    if(pbal == 0){
        interest = 0.0;
        nbal=pbal+ tnc;
    }
    else{ 
        interest = (pbal+tnc)*0.2;//0.2=20/100
        nbal=pbal + interest + tnc;
    }
    if(nbal<50){
        mp=nbal;
    }
    if(nbal>50 && nbal<300){
        mp=50;
    }
    if(nbal>300){
     mp=nbal *0.2;   //0.2=20/100
    }
    System.out.println("old balance" + pbal + " " + "total new charges" + tnc);
    System.out.println("new balance" + nbal + " " + "interest" + interest + " " + "minimal pay" + mp);

}

}

希望这会有所帮助。