java - 如何在java中格式化输出控制台列？

Question

我编写了一个程序来创建发票，但是当它的数量达到数千时，输出并不整齐并且会毁掉一切。我该如何解决这个问题，以便程序的列与这样的数字更加一致？这是我用来创建程序的代码。如果有人能提供帮助，我将非常感激。

这是主要方法...

public class InvoicePrinter
{
public static void main(String[] args)
  {

  Address samsAddress=new Address("Sam's Small Appliances", "100 Main 
  Street", "Anytown", "CA", "98765");
  Invoice samsInvoice =new Invoice(samsAddress);
  samsInvoice.add(new Product("Toaster", 29.95),3);
  samsInvoice.add(new Product("Hair Dryer", 24.95),1);      
  samsInvoice.add(new Product("Car Vacuum",19.99),2);
  samsInvoice.add(new Product("Nano Parts",100000),1);
  samsInvoice.addSimple(new Product("Shipping",5.00));

  System.out.println(samsInvoice.format());
  }
}

这些是程序运行所需的其他程序

import java.util.ArrayList;

public class Invoice
{
  public Invoice(Address anAddress)
  {
  items=new ArrayList<LineItem>();
  billingAddress=anAddress;
  simpleItems= new ArrayList<SimpleLineItem>();
}

public void addSimple(Product aProduct)
{
  SimpleLineItem anItem= new SimpleLineItem(aProduct);
  simpleItems.add(anItem);
}


public void add(Product aProduct, int quantity)
{
  LineItem anItem=new LineItem(aProduct,quantity);
  items.add(anItem);
}   

 public String format()
 {
  String r="                                                 I N V O I C E\n\n"+billingAddress.format()+String.format("\n\n%-30s%8s%5s%8s\n","Description", "Price","Qty","Total");

  for(LineItem i:items)
  {
     r=r+i.format()+"\n";
  }

  for(SimpleLineItem j:simpleItems)
  {
   r=r+j.format() + "\n";
  }

  r = r + String.format("\nAMOUNT DUE: $%8.2f", getAmountDue());
  return r;
  }

 public double getAmountDue()
 {
  double amountDue = 0;
  for (LineItem i : items)
  {
      amountDue = amountDue + i.getTotalPrice();
  }
  for(SimpleLineItem j:simpleItems)
  {
     amountDue = amountDue + j.getPrice();
  }
 return amountDue; 
  }     


 private Address billingAddress;
 private ArrayList<LineItem> items;
 private ArrayList<SimpleLineItem> simpleItems;
}

还有一点

public class LineItem
{
 public LineItem(Product aProduct, int aQuantity)
 {
  theProduct = aProduct;
  quantity = aQuantity;
 }

 public double getTotalPrice()
 {
  return theProduct.getPrice() *quantity;
 }

 public String format()
 {
  return String.format("%'-30s%'8.2f%'5d%'8.2f", theProduct.getDescription(),theProduct.getPrice(),quantity,getTotalPrice());
 }

 private int quantity;
 private Product theProduct;
}

另一个

public class SimpleLineItem
{
  public SimpleLineItem(Product aProduct)
  {
     theProduct=aProduct;
  }

  public double getPrice()
  {
     return theProduct.getPrice();   
  }

  public String format()
  {
    return String.format("%-30s" +"             " + "%8.2f",
    theProduct.getDescription(), theProduct.getPrice());
  }

  private Product theProduct;
  }  

还有两个

  public class Product
  {  
   public Product(String aDescription,double aPrice)
   {
     description = aDescription;
     price = aPrice;
   }

   public String getDescription()
   {
     return description;
   }

   public double getPrice()
   {
     return price;
   }

   private String description;
   private double price;
   }

最后一张

   public class Address
   {
     public Address(String aName, String aStreet, String aCity, String 
     aState,String aZip)
    {
       name = aName;
       street = aStreet;
       city = aCity;
       state = aState;
       zip = aZip;
    }

   public String format()
   {
     return name + "\n" + street + "\n" + city + ", " + state + " " + zip;
   }

   private String name;
   private String street;
   private String city;
   private String state;
   private String zip;
  }

Answer 1

也许你可以看看 Oracle 关于 System.out.format 和 DecimalFormat 类的 javadocs

Formatting Numeric Print Output