我的代码(读取文本文件,使用我构建的类来对数据进行排序,然后输出到控制台上),不打印任何内容!有人可以告诉我我的小错误在哪里!我知道非常结束还没有结束。请帮忙!!!!!!!!
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
public class Project02 {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
ArrayList<Product> products = new ArrayList<Product>();
// Enter file name
System.out.print("Enter database file name: ");
String fileName = in.nextLine();
try {
File file = new File(fileName);
Scanner inputFile = new Scanner(file);
System.out.println();
while (inputFile.hasNext()) {
Product p = new Product();
String title = inputFile.nextLine();
String code = inputFile.nextLine();
Integer quantity = inputFile.nextInt();
Double price = inputFile.nextDouble();
inputFile.nextLine();
String type = inputFile.nextLine();
Integer userReview = inputFile.nextInt();
// read in title
p.setName(title);
// read in iCode
p.setInventoryCode(code);
// read in quantity
p.setQuantity(quantity);
// read in price
p.setPrice(price);
// read in type
p.setType(type);
// read in user reviews
while (!userReview.equals(-1)) {
p.addUserRating(userReview);
userReview = inputFile.nextInt();
}
if (inputFile.hasNext()) {
inputFile.nextLine();
}
}
inputFile.close();
} catch (IOException e) {
System.out.println("There was an error reading from " + fileName);
}
}
private static String highRating(ArrayList<Product> p) {
int highestR = 0;
int indexOfHighestR = 0;
for (int i = 0; i < p.size(); i++) {
int rating = p.get(i).getAvgUserRating();
if (p.get(i).getAvgUserRating() > highestR) {
highestR = p.get(i).getAvgUserRating();
indexOfHighestR = i;
}
}
int zero = 0;
String Star = " ";
while (highestR > zero) {
Star = Star + "*";
zero--;
}
String highestRateTitle = p.get(indexOfHighestR).getName() + " ("
+ Star + ")";
return highestRateTitle;
}
private static String lowestRating(ArrayList<Product> p) {
int lowestR = 0;
int indexOfLowestR = 0;
for (int i = 0; i < p.size(); i++) {
int rating = p.get(i).getAvgUserRating();
if (p.get(i).getAvgUserRating() < lowestR) {
lowestR = p.get(i).getAvgUserRating();
indexOfLowestR = i;
}
}
int zero = 0;
String Star = " ";
while (lowestR > zero) {
Star = Star + "*";
zero--;
}
String highestRateTitle = p.get(indexOfLowestR).getName() + " ("
+ Star + ")";
return highestRateTitle;
}
private static double maxDollar(ArrayList<Product> p) {
double largestP = 0;
int indexOfLargestP = 0;
for (int i = 0; i < p.size(); i++) {
double price = p.get(i).getPrice();
if (p.get(i).getPrice() > largestP) {
largestP = p.get(i).getPrice();
indexOfLargestP = i;
}
}
return largestP;
}
private static int minDollar(ArrayList<Product> p) {
double smallestP = p.get(0).getPrice();
int indexOfSmallestP = 0;
for (int i = 0; i < p.size(); i++) {
if (p.get(i).getPrice() < smallestP) {
smallestP = p.get(i).getPrice();
indexOfSmallestP = i;
}
}
return indexOfSmallestP;
}
private static void inventoryList(ArrayList<Product> p) {
int count =
System.out.println("Product Summary Report: ");
System.out
.println("------------------------------------------------------------");
for (int i = 0; i < count; i++) {
System.out.println("Title: " + p.get(i).getName());
System.out.println("I Code: " + p.get(i).getInventoryCode());
System.out.println("Product Type: " + p.get(i).getType());
System.out.println("Rating: " + p.get(i).getAvgUserRating());
System.out.println("# Rat.: " + p.get(i).getUserRatingCount());
System.out.println("Quantity: " + p.get(i).getQuantity());
System.out.println("Price: " + p.get(i).getPrice());
System.out.println();
}
System.out
.println("-----------------------------------------------------------------");
// System.out.println("Total products in database: " + count);
System.out.println("Highest total dollar item: "
+ p.get(maxDollar(p)) + " ($"+ p.(maxDollar(p)) + ")");
System.out.println("Smallest quantity item: "
+ p.get(minQuantity(quantities)) + " ("
+ types.get(minQuantity(quantities)) + ")");
System.out.println("Lowest total dollar item: "
+ titles.get(minDollar(prices)) + " ($"
+ prices.get(minDollar(prices)) + ")");
System.out
.println("-----------------------------------------------------------------");
}
答案 0 :(得分:1)
在您创建Product
,p
的实例后,您需要将其添加到products
列表中,否则您将丢失它的参考,将无法使用再次使用它......
while (inputFile.hasNext()) {
Product p = new Product();
//...
products.add(p);
if (inputFile.hasNext()) {
inputFile.nextLine();
}
}
您需要将products
List
传递给想要使用/显示信息的内容,例如inventoryList
...
但等等,那不行?
如果我们仔细看看inventoryList
方法......
int count = 0;
//...
for (int i = 0; i < count; i++) {
我们可以看到count
始终是0
,因此它永远不会打印任何内容!您应该使用p.size()
代替,products
List
//...
for (int i = 0; i < p.size(); i++) {