從Java中的文本文件讀取輸入

Question

我需要編寫一個從.txt文件讀取並創建新的“ InventoryItem”對象並將其添加到“ Warehouse”對象的方法。 Warehouse類創建InventoryItem的數組列表。 我正在使用掃描儀讀取文本文件，但不了解如何將這些值帶入我創建的新Warehouse對象中。

文本文件如下所示：

Purple Widget

1234 17.95 150

我的方法：

public Warehouse readInventoryFile(File inputFile) throws FileNotFoundException {
    Warehouse warehouse1 = new Warehouse();
    Scanner in = new Scanner(inputFile);

    while(in.hasNext()) {
    String item = in.nextLine();
    int sku = in.nextInt();
    double price = in.nextDouble();
    int stock = in.nextInt();
    String nextLine = in.nextLine();

}
    return warehouse1;

}

InventoryItem類：

public class InventoryItem{
    private final int sku;
    private final String item;
    private double price;
    private int stock;

public InventoryItem(int sku, String item, double price, int stock){
    this.sku = sku;
    this.item = item;
    this.price = price;
    this.stock = stock;

  }//InventoryItem constructor

  public int getSku(){
    return sku;
  }//getSKU

  public String getItem(){
    return item;
  }//getItem

  public void setPrice(double price){
    this.price = price;
  }//setPrice

  public double getPrice(){
    return price;
  }//getPrice

  public void setStock(int stock){
    this.stock = stock;
  }//setStock

  public int getStock(){
    return stock;
  }//getStock


        @Override
  public String toString(){
    return String.format("[%d, %s, %1.2f, %d]", sku, item, price, stock);
  }//toString

  public static void main(String[] args){
    InventoryItem itemName = new InventoryItem(1234, "crackers", 2.50, 4);
    itemName.toString();

  }//main

}//InventoryItem

倉庫類：

import java.util.ArrayList;

public class Warehouse {

    private final ArrayList<InventoryItem> inventory;

    public Warehouse() {
        inventory = new ArrayList<>();
    }//constructor

    public void addItem(InventoryItem item) {
        inventory.add(item);
    }//addItem

    private int findHelper(int sku) {
        int index = 0;
        while (index < inventory.size()) {
            if (sku == inventory.get(index).getSku()) {
                return index;
            }//if
            index++;
        }//while
        return -1;
    }//findHelper

    public InventoryItem findItem(int sku) {
        int index = findHelper(sku);
        return inventory.get(index);
    }//findItem

    public InventoryItem removeItem(int sku) {
        int index = findHelper(sku);
        return inventory.remove(index);
    }//removeItem

    public void updateItemQuantity(int sku, int stock) {
        int index = findHelper(sku);
        inventory.get(index).setStock(stock);
    }//updateItemQuantity

    public void updateItemPrice(int sku, double price) {
        int index = findHelper(sku);
        inventory.get(index).setPrice(price);
    }//updateItemPrice

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < inventory.size(); i++) {
            sb.append(inventory.get(i).toString()).append(", ");
        }//for
        return this.inventory.toString();
    }//toString

    private int seqSearchRecHelper(int sku, int index) {
        if (index < inventory.size()) {
            if (sku == inventory.get(index).getSku()) {
                return index;
            }//if sku ==
            return seqSearchRecHelper(sku, index + 1);
        }//if index
        return -1;
    }//seqSearchHelper

    public InventoryItem seqSearchRec(int sku) {
        int i = seqSearchRecHelper(sku, 0);
        if (i == -1) {
            return null;
        }//if
        return inventory.get(i);
    }//seqSearchRec

    public void selectSort() {
        int largestIndex;
        int largest;
        //for (int i = inventory.size() - 1; i > 0; i--) {
        for(int i = 0; i<inventory.size(); i++){
            largest = inventory.get(0).getSku();
            largestIndex = i;
            for (int j = i+1; j < inventory.size(); j++) {
                if (largest < inventory.get(j).getSku()) {
                    largest = inventory.get(j).getSku();
                    largestIndex = j;
                    //largest++;
                }//if
            }//for j
            InventoryItem temp = inventory.get(i);
            inventory.set(i, inventory.get(largestIndex));
            inventory.set(largestIndex, temp);

        }//for i
    }//selectSort 

    public InventoryItem binSearch(int sku) {
        return binSearchHelper(sku, 0, inventory.size()-1);
    }//binSearch

    private InventoryItem binSearchHelper(int sku, int start, int end) {
        if(start>end){return null;}
        int mid=(start+end)/2;
        if(sku == inventory.get(mid).getSku()){return inventory.get(mid);}
        if(sku<inventory.get(mid).getSku()){return binSearchHelper(sku, start, mid-1);}
        return binSearchHelper(sku, mid+1, end);



    }//binSearchHelper

    public int size() {
        return inventory.size();
    }

    /**
     *
     * @param index
     * @return 
     */
    public InventoryItem getItem(int index) {
        return inventory.get(index);
    }

    public static void main(String[] args) {

        Warehouse item = new Warehouse();
        Warehouse item2 = new Warehouse();
        item.addItem(new InventoryItem(10, "crackers", 2.00, 10));
        item.addItem(new InventoryItem(11, "chips", 4.99, 300));
        item.addItem(new InventoryItem(1, "toothpicks", 0.39, 600));

        System.out.println("All items (toString): " + item);
        System.out.println("Item sku 10: " + item.findItem(10));
        System.out.println("Item sku 11: " + item.findItem(11));
        System.out.println("Item sku 1: " + item.findItem(1));

        item.updateItemQuantity(10, 11);
        item.updateItemQuantity(11, 400);
        item.updateItemQuantity(1, 599);

        System.out.println();

        System.out.println("Quantity updated (sku 10): " + item.findItem(10));
        System.out.println("Quantity updated (sku 11): " + item.findItem(11));
        System.out.println("Quantity updated (sku 1): " + item.findItem(1));

        item.updateItemPrice(10, 3.00);
        item.updateItemPrice(11, 3.99);
        item.updateItemPrice(1, 0.49);

        System.out.println();

        System.out.println("Price updated - sku 10: " + item.findItem(10));
        System.out.println("Price updated - sku 11: " + item.findItem(11));
        System.out.println("Price updated - sku 1: " + item.findItem(1));

        System.out.println();

        System.out.println("seqSearchRec - sku 10: " + item.seqSearchRec(0));
        System.out.println("seqSearchRec - sku 11: " + item.seqSearchRec(1));
        System.out.println("seqSearchRec - sku 1: " + item.seqSearchRec(2));

        System.out.println();

        System.out.println("All items updated (toString): " + item);
        //System.out.println("Items to remove: " + item.removeItem(10) + item.removeItem(11));
        //System.out.println("Items left in inventory: " + item);

        //item.selectSort();
        //System.out.println("SelectSort: " + item);
        System.out.println("seqSearchRec (expected null): " + item.seqSearchRec(2));
        System.out.println("seqSearchRec - sku 1: " + item.seqSearchRec(1));
        System.out.println("seqSearchRec - sku 10: " + item.seqSearchRec(10));
        System.out.println("seqSearchRec - sku 11: " + item.seqSearchRec(11));

        System.out.println("binSearch 10: " + item.binSearch(10));
        System.out.println("binSearch 11: " + item.binSearch(11));

        item.selectSort();
        System.out.println("selectSort: " + item);
        System.out.println(item.size());
        System.out.println(item.getItem(1));
    }//main
}//Warehouse

Answer 1

您需要先創建一個InventoryItem，然后再將其添加到Warehouse對象中：

public Warehouse readInventoryFile(File inputFile) throws FileNotFoundException {
Warehouse warehouse1 = new Warehouse();
Scanner in = new Scanner(inputFile);

while(in.hasNext()) {
String item = in.nextLine();
int sku = in.nextInt();
double price = in.nextDouble();
int stock = in.nextInt();
String nextLine = in.nextLine();

InventoryItem myItem = new InventoryItem(sku, item, price, stock);
warehouse1.addItem(myItem);
}