java，初学者求救

import java.util.Scanner;public class InvoiceTest{    public static void main(String args[])    {        Invoice invoice = new Invoice();        Scanner put = new Scanner(System.in);        int A;        String str1;        String str2;        double b;        System.out.println("enter InvoiceCode:");        str1 = put.nextLine();        invoice.setInvoiceCode(str1);        System.out.println("enter InvoiceText:");        str2 = put.nextLine();        invoice.setInvoiceText(str2);        System.out.println("enter InvoiceNumber:");        A = put.nextInt();        invoice.setInvoiceNumber(A);        System.out.println("enter Invoicebalance:");        b = put.nextDouble();        invoice.setInvoicebalance(b);        System.out.printf("code:%s,text:%s,number:%d,accout:%.2f",str1,str2,A,invoice.getInvoiceAmount());//        System.out.println(invoice.getInvoiceAmount());    }}class Invoice{    private double balance;    private String invoiceCode;    private String invoiceText;    private int invoiceNumber;    private double invoiceBalance;        public Invoice()    {            }    public void setInvoiceCode(String code)    {        invoiceCode=code ;    }    public void setInvoiceText(String text)    {        invoiceText=text;    }    public void setInvoiceNumber(int number)    {        invoiceNumber=number ;    }    public void setInvoicebalance(double amount)    {        invoiceBalance=amount;    }    public double getInvoiceAmount()    {        if(invoiceBalance>0.0)            balance = invoiceBalance*invoiceNumber;        return balance;    }}
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Java code
import java.util.Scanner;public class InvoiceTest {    public static void main(String args[]) {    Invoice invoice = new Invoice(0);    Scanner put = new Scanner(System.in);    int A;    String str1;    String str2;    double b;    System.out.println("enter:");// invoiceCode    str1 = put.nextLine();    if (!str1.matches("[\\d]+")) {        System.out.println("errot");        System.exit(0);    }    invoice.setInvoiceCode(str1);    System.out.println("enter:"); // invoiceText    str2 = put.nextLine();    if (!str2.matches("[\\d]+")) {        System.out.println("errot");        System.exit(0);    }    invoice.setInvoiceText(str2);    System.out.println("enter:");// invoiceNumber    A = put.nextInt();    invoice.setInvoiceNumber(A);    System.out.println("enter:");// invoicebalance    b = put.nextDouble();    invoice.setInvoicebalance(b);            /*    System.out.printf("code:%s,text:%s,number:%d,accout:%.2f", str1, str2,        A, b, invoice.getInvoiceAmount());//为什么这里有5个输出，但是控制格式符只有4个        */        System.out.printf("code:%s,text:%s,number:%d,accout:%.2f，getinvoiceBalance = %.2f " ,str1, str2,        A, b, invoice.getInvoiceAmount());        }}class Invoice {    private double balance;    private String invoiceCode;    private String invoiceText;    private int invoiceNumber;    public double invoiceBalance;    // ///////////////////////////////////////////////////////////    public Invoice(double balance) {//这里的构造函数不起作用    int number = 0;    double amount = 0.0;    if (invoiceBalance > 0.0)// 系统默认初始化invoicebalance为0.0        balance = amount * number;// 这里干什么的？？？一点作用都没有    }    // //////////////////////////////////////////////////////////    public void updateInvoiceBalance(int amount, double number) {    if (invoiceBalance > 0.0)        balance = amount * number;    }    // //////////////////////////////////////////////////////////    public void setInvoiceCode(String code) {    //code = invoiceCode;// 这里又是干神马的？？？？？    invoiceCode = code;    }    public void setInvoiceText(String text) {    //text = invoiceText;// 这里又是干神马的？？？？？    invoiceText = text;    }    public void setInvoiceNumber(int number) {    //number = invoiceNumber;// 这里又是干神马的？？？？？    invoiceNumber = number;    }    public void setInvoicebalance(double amount) {    //amount = invoiceBalance;// 这里又是干神马的？？？？？    invoiceBalance = amount*invoiceNumber;    }    public double getInvoiceAmount() {//为什么不取名字getInvoiceBalance        balance = invoiceBalance;    //return balance;// 这里又是干神马的？？？？？    return invoiceBalance;    }}