[英]I have an sorted an array that was read from a file, but it won't print
我編寫了一個代碼來讀取文件,並按價格對其進行排序,然后在繼續檢查功能之前將其輸出,並且可以正確編譯,但是在輸出時卻給了我很多空白。
這是我的代碼-
import java.util.*;
import java.io.*;
public class Program5
{
public static int[] pluCode = new int[100];
public static String[] names = new String[100];
public static double[] storePrice = new double[100];
public static int[] type = new int[100];
public static double total = 0;
public static void main(String[]args) throws IOException
{
loadFile("products.txt");
sortFile();
getPLU();
System.exit(0);
}
public static void getPLU()
{
Scanner keyboard = new Scanner(System.in);
System.out.println("\n What is the PLU code of your next product? Type 0");
System.out.println(" to check out.");
int pluInput = keyboard.nextInt();
if (pluInput != 0)
{
int index = pluSearch(pluInput);
if (index != -1)
{
retrieveProduct(index);
}
else
{
System.out.println("Invalid PLU code.");
getPLU();
}
}
else
{
out();
}
}
public static void sortFile()throws IOException
{
for ( int i =0 ; i < storePrice.length ; i++)
{
PrintWriter outputFile = new PrintWriter ("products2.txt");
outputFile.print(pluCode[i] + " " + names[i] + " " + type[i] + " " + storePrice[i]+ " ");
//outFile.print(calcPay(names[i], pluCode[i], type[i]) + " " + calcTax(storePrice[i]));
System.out.println(pluCode[i] + " " + names[i] + " " + type[i] + " " + storePrice[i] + " ");
outputFile.close();
}
}
public static void retrieveProduct(int index)
{
if(type[index] == 1)
{
System.out.println("How much do the " + names[index] + " weigh?");
Scanner keyboard = new Scanner(System.in);
total += storePrice[index] * keyboard.nextDouble();
System.out.println("So far it costs " +(total));
getPLU();
}
else
{
System.out.println("Number of units is?" + names[index]);
Scanner keyboard = new Scanner(System.in);
total += storePrice [index] * keyboard.nextInt();
System.out.println("So far it costs " +(total));
getPLU();
}
}
public static void out()
{
System.out.println("Your total is $" +(total));
double discount = 0;
if (total > 50)
{
discount = total * .05;
total -= discount;
}
System.out.println(" Your discount is $" + discount);
System.out.println(" Your total charge is $" + total);
if (user())
{
getPLU();
}
else
{
System.exit(0);
}
}
public static boolean user()
{
System.out.println("Enter Y for next customer. Enter N to exit.");
Scanner keyboard = new Scanner(System.in);
String reply = keyboard.nextLine();
int yes = reply.indexOf("Y");
int no = reply.indexOf("N");
if (yes != -1)
{
System.out.println("Next customer.");
return true;
}
else if(no != -1)
{
System.out.println("Thank you for your business.");
return false;
}
else
{
System.out.println("Invalid answer. Type Y or N.");
return user();
}
}
public static int pluSearch(int pluInput)
{
int index = 0;
for (int value : pluCode)
{
if (value == pluInput)
return index;
else
index++;
}
return -1;
}
public static void loadFile(String str)throws IOException
{
Scanner input;
File file = new File(str);
if(!file.exists())
{
System.out.println("Could not open file.");
System.exit(0);
}
input = new Scanner(file);
int index = 0;
while (input.hasNext())
{
pluCode[index] = Integer.parseInt(input.next());
names[index] = input.next();
type[index] = Integer.parseInt(input.next());
storePrice[index] = Double.parseDouble(input.next());
index++;
}
input.close();
}
}
這是輸出:
----jGRASP exec: java Program5
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
0 null 0 0.0
問題是什么?
在讀取數據時打印數據:
while ( input.hasNext() ) {
pluCode[index] = Integer.parseInt(input.next());
names[index] = input.next();
type[index] = Integer.parseInt(input.next());
storePrice[index] = Double.parseDouble(input.next());
System.out.println(pluCode[index] + " " + names[index] + " " + type[index] + " " + storePrice[index] + " ");
index++;
}
很可能您沒有從文件中讀取任何數據。
讀入時,您需要打印出這些值。文件很可能是空的,並且永遠不會將數據放入數組中。
從文件加載時,還需要將index
的最大值存儲在某個位置,以便知道讀取了多少個條目。 現在您正在執行的是打印全部100條記錄,無論您是否閱讀。
您正在為數據分配固定大小的數組:
public static double[] storePrice = new double[100];
public static int[] type = new int[100];
然后嘗試在輸出例程中使用這些數組的長度:
public static void sortFile() throws IOException {
for (int i = 0; i < storePrice.length; i++) {
PrintWriter outputFile = new PrintWriter("products2.txt");
outputFile.print(pluCode[i] + " " + names[i] + " " +
type[i] + " " + storePrice[i] + " ");
System.out.println(pluCode[i] + " " + names[i] + " " +
type[i] + " " + storePrice[i] + " ");
outputFile.close();
}
}
storePrice.length
將永遠是100
在你的程序,不管你讀一個條目或幾十個或100(它會崩潰在100以上,這可能是罰款一門功課程序)。
由於長度始終為100
,因此無法將其用於這樣的迭代范圍。 您應該稍后將輸入例程中的index
存儲在文件中,以跟蹤實際擁有的項數。
絕對不要為每個行創建和關閉outputFile
這個循環。 在循環外部將其打開一次,使用它,然后在循環外部將其關閉。
我建議更改您的例程的名稱。 您的輸入名為loadFile()
,這很好,但您的輸出例程名為sortFile
,它根本不進行排序。 當我閱讀您的main()
,我看到了:
loadFile("products.txt");
sortFile();
getPLU();
我期望看到的是:
loadFile("products.txt");
sortFile();
saveFile("sorted_products.txt");
getPLU();
/* and so on */
使您的方法按其名稱所言,將您的方法配對為邏輯組,例如“加載/保存”,“打開/關閉”,“讀/寫”,“ setPLU / getPLU”等。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.