我需要接受产品的价格，数量并打印账单。但它为其他变量打印null而不是字符串和零 [英] I need to accept the price, quantity of a product and print the bill. But it prints null instead of string and zeros for other variables

问题描述

 import java.util。*; 
 class产品
 {
字符串名称; 
浮动价格; 
 int qty; 
浮动账单，光盘，nbill; 
} 
 class Rect 
 {
 public static void main（String [] args）
 {
 Scanner sc = new Scanner（System.in）; 
产品p =新产品（）; 
 
 System.out.print（产品名称：）; 
 String name = sc.nextLine（）; 
 System.out.print（price：）; 
浮动价格= sc.nextFloat（）; 
 System.out.print（quantity）; 
 int qty = sc.nextInt（）; 
 
 p.bill = p.price * p.qty; 
 p.disc = p.bill * 5/100; 
 p.nbill = p.bill-p.disc; 
 
 System.out.println（产品名称：+ p.name +价格：+ p.price +数量：+ p.qty +Bill：+ p.bill +折扣： + p.disc +净账单：+ p.nbill）; 
} 
} 

我的尝试：



它打印null而不是字符串名称和零而不是值

解决方案

引用：

它打印null而不是字符串名称和零而不是值

重读你的代码，并注意你存储的变量与您打印的内容相关的值。有一个惊喜。



您的代码没有按照您的预期行事，您不明白为什么！


有一个几乎通用的解决方案：逐步在调试器上运行代码，检查变量。

调试器在这里向您展示您的代码正在做什么，您的任务是比较它应该做什么。

调试器中没有魔法，它不知道你应该做什么，它没有找到错误，它只是通过向你展示什么来帮助你正在进行。当代码没有达到预期的效果时，你就接近了一个错误。

要查看你的代码在做什么：只需设置断点并查看代码是否正常运行，调试器允许你执行第1行第1行并在执行时检查变量。



此解决方案的缺点：

- 这是一个DIY，你是跟踪问题并找到根源的那个，这导致了解决方案。

这个解决方案的优点：

- 它也是一个很好的学习工具，因为它告诉你现实，你可以看到哪种期望与现实相符。



次要效果

- 你会为自己找到虫子感到自豪。

- 你的学习技巧会提高。



你应该很快就会发现什么是错的。



调试器 - 维基百科，免费的百科全书 [ ^ ]

http：// docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html [ ^ ]

https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html [ ^ ]

调试器仅用于显示代码正在执行的操作，并且您的任务是与应该执行的操作进行比较。

import java.util.*;
class Product
{
     String name;
	 float price;
	 int qty;
	 float bill,disc,nbill;
}
class Rect
{
	public static void main(String[] args) 
	{
		Scanner sc=new Scanner(System.in);
		Product p=new Product();
	
		System.out.print("product name: ");
		String name=sc.nextLine();
		System.out.print("price:");
		float price=sc.nextFloat();
		System.out.print("quantity");
		int qty=sc.nextInt();
       
         p.bill=p.price*p.qty;
		p.disc=p.bill*5/100;
		p.nbill=p.bill-p.disc;
		
		System.out.println("Product name : "+p.name+"Price : "+p.price+"Quantity : "+p.qty+"Bill : "+p.bill+"Discount : "+p.disc+"Net bill : "+p.nbill);
		}
}

What I have tried:

it prints null instead of string name and zeros instead of values

解决方案

Quote:

it prints null instead of string name and zeros instead of values

reread your code, and pay attention to the variables where you store the values against what you print. There is a surprise.

Your code do not behave the way you expect, and you don't understand why !

There is an almost universal solution: Run your code on debugger step by step, inspect variables.
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't know what your is supposed to do, it don't find bugs, it just help you to by showing you what is going on. When the code don't do what is expected, you are close to a bug.
To see what your code is doing: Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute.

The downside of this solution:
- It is a DIY, you are the one tracking the problem and finding its roots, which lead to the solution.
The upside of this solution:
- It is also a great learning tool because it show you reality and you can see which expectation match reality.

secondary effects
- Your will be proud of finding bugs yourself.
- Your learning skills will improve.

You should find pretty quickly what is wrong.

Debugger - Wikipedia, the free encyclopedia[^]
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html[^]
https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html[^]
The debugger is here to only show you what your code is doing and your task is to compare with what it should do.

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