java，菜鸟求救！

Question

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:");
str1 = put.nextLine();
invoice.setInvoiceCode(str1);
System.out.println("enter:");
str2 = put.nextLine();
invoice.setInvoiceText(str2);
System.out.println("enter:");
A = put.nextInt();
invoice.setInvoiceNumber(A);
System.out.println("enter:");
b = put.nextDouble();
invoice.setInvoicebalance(b);
System.out.printf("code:%s,text:%s,number:%d,accout:%.2f",str1,str2,A,b,invoice.getInvoiceAmount());
}}
class Invoice
{
private double balance;
private String invoiceCode;
private String invoiceText;
private int invoiceNumber;
private double invoicebalance;
public Invoice(double balance)
{
int number = 0;
double amount = 0.0;
if(invoicebalance>0.0)
balance = amount*number;
} public void setInvoiceCode(String code)
{
code = invoiceCode;
}
public void setInvoiceText(String text)
{
text = invoiceText;
}
public void setInvoiceNumber(int number)
{
number = invoiceNumber;
}
public void setInvoicebalance(double amount)
{
amount = invoicebalance;
}
public double getInvoiceAmount()
{
return balance;
}

}
为什么运行后，没有我想要等到的结果。invoice.getInvoiceAmount());没有返回他们的积？

Answer 1

不是很清楚你想要计算的数值，你看看是下面程序的效果么？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;
    }}

Answer 2

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;
    }}

Answer 3

Invoice invoice = new Invoice(0);//这儿传的参数是0，最后算出来的就是0啊。
而且你这个程序的逻辑不对，劝楼主先理清思路