java - 如何才能更有效地调用多个 ListIterator？

Question

所以我的问题是，是否可以通过使用带有列表名称(foodList、foodAmount 等)的数组来简化这段代码，而不是用列表名称(来自所述数组)进行某种循环来替换迭代器中的占位符？

这是代码:

public static void writeFile() throws IOException{
    ListIterator<String> foodIterator = GrocerieList.foodList.listIterator(0);
    ListIterator<Integer> foodAmountIterator = GrocerieList.foodAmount.listIterator(0);
    ListIterator<String> drinkIterator = GrocerieList.drinkList.listIterator(0);
    ListIterator<Integer> drinkAmountIterator = GrocerieList.drinkAmount.listIterator(0);

    FileWriter writer = new FileWriter("/Users/c-mon/IdeaProjects/final/src/shoppingList.txt");

    // FOOD
    writer.write("foodList");
    writer.write(System.getProperty( "line.separator" ));
    if(foodIterator.hasNext()){
        do{
            writer.write(foodIterator.next());
            writer.write(System.getProperty( "line.separator" ));
        }while(foodIterator.hasNext());
    }else{
        writer.write("empty");
        writer.write(System.getProperty( "line.separator" ));
    }

    writer.write("foodAmount");
    writer.write(System.getProperty( "line.separator" ));
    if(foodAmountIterator.hasNext()){
        do{
            writer.write(foodAmountIterator.next() + "");
            writer.write(System.getProperty( "line.separator" ));
        }while(foodAmountIterator.hasNext());
    }else{
        writer.write("empty");
        writer.write(System.getProperty( "line.separator" ));
    }

    // DRINKS
    writer.write("drinkList");
    writer.write(System.getProperty( "line.separator" ));
    if(drinkIterator.hasNext()){
        do{
            writer.write(drinkIterator.next());
            writer.write(System.getProperty( "line.separator" ));
        }while(drinkIterator.hasNext());
    }else{
        writer.write("empty");
        writer.write(System.getProperty( "line.separator" ));
    }

    writer.write("drinkAmount");
    writer.write(System.getProperty( "line.separator" ));
    if(drinkAmountIterator.hasNext()){
        do{
            writer.write(drinkAmountIterator.next() + "");
            writer.write(System.getProperty( "line.separator" ));
        }while(drinkAmountIterator.hasNext());
    }else{
        writer.write("empty");
        writer.write(System.getProperty( "line.separator" ));
    }

    writer.close();
}

这是声明列表的地方

import java.util.ArrayList;
import java.util.ListIterator;

public class GrocerieList {

    static ArrayList<String> foodList = new ArrayList<>();
    static ArrayList<String> hygieneList = new ArrayList<>();
    static ArrayList<String> drinkList = new ArrayList<>();
    static ArrayList<String> otherList = new ArrayList<>();

    static ArrayList<Integer> foodAmount = new ArrayList<>();
    static ArrayList<Integer> hygieneAmount = new ArrayList<>();
    static ArrayList<Integer> drinkAmount = new ArrayList<>();
    static ArrayList<Integer> otherAmount = new ArrayList<>();

    public static void foodOutput (){
        ListIterator<String> foodListIterator = foodList.listIterator(0);
        ListIterator<Integer> foodAmountIterator = foodAmount.listIterator(0);

        if(foodListIterator.hasNext()){
            System.out.println("\t" + "Food");
            do {
                System.out.println("\t" + foodAmountIterator.next() + "\t\t" + "\t--\t" + "\t\t" + foodListIterator.next());
            }while (foodListIterator.hasNext());
            System.out.println(" ");
        }else{
            System.out.println("\t" + "Food");
            System.out.println("\t" + "No food on your list");
            System.out.println(" ");
        }
    }
    public static void drinkOutput (){
        ListIterator<String> drinkListIterator = drinkList.listIterator(0);
        ListIterator<Integer> drinkAmountIterator = drinkAmount.listIterator(0);

        if(drinkListIterator.hasNext()){
            System.out.println("\t" + "Drinks");
            do {
                System.out.println("\t" + drinkAmountIterator.next() + "\t\t" + "\t--\t" + "\t\t" + drinkListIterator.next());
            }while (drinkListIterator.hasNext());
            System.out.println(" ");
        }else{
            System.out.println("\t" + "Drinks");
            System.out.println("\t" + "No drinks on your list");
            System.out.println(" ");
        }
    }
    public static void hygieneOutput (){
        ListIterator<String> hygieneListIterator = hygieneList.listIterator(0);
        ListIterator<Integer> hygieneAmountIterator = hygieneAmount.listIterator(0);

        if(hygieneListIterator.hasNext()){
            System.out.println("\t" + "Hygiene");
            do {
                System.out.println("\t" + hygieneAmountIterator.next() + "\t\t" + "\t--\t" + "\t\t" + hygieneListIterator.next());
            }while (hygieneListIterator.hasNext());
            System.out.println(" ");
        }else{
            System.out.println("\t" + "Hygiene");
            System.out.println("\t" + "No hygiene products on your list");
            System.out.println(" ");
        }
    }
    public static void otherOutput (){
        ListIterator<String> otherListIterator = otherList.listIterator(0);
        ListIterator<Integer> otherAmountIterator = otherAmount.listIterator(0);

        if(otherListIterator.hasNext()){
            System.out.println("\t" + "Other products");
            do {
                System.out.println("\t" + otherAmountIterator.next() + "\t\t" + "\t--\t" + "\t\t" + otherListIterator.next());
            }while (otherListIterator.hasNext());
            System.out.println(" ");
        }else{
            System.out.println("\t" + "Other Products");
            System.out.println("\t" + "No other products on your list");
            System.out.println(" ");
        }
    }

    public static void rewe (){
        System.out.println("########################################");
        System.out.println(" ");
        System.out.println("Here is your REWE shopping list!");
        System.out.println(" ");
        System.out.println("\t" + "Qty" + "\t\t" + "\t--\t" + "\t\t" + "Product");
        System.out.println(" ");
        foodOutput();
        drinkOutput();
        hygieneOutput();
        otherOutput();
        System.out.println(" ");
        System.out.println("########################################");
    }
    public static void lidl (){
        System.out.println("########################################");
        System.out.println(" ");
        System.out.println("Here is your LIDL shopping list!");
        System.out.println(" ");
        System.out.println("\t" + "Qty" + "\t\t" + "\t--\t" + "\t\t" + "Product");
        System.out.println(" ");
        drinkOutput();
        foodOutput();
        otherOutput();
        hygieneOutput();
        System.out.println(" ");
        System.out.println("########################################");
    }
    public static void edeka (){
        System.out.println("########################################");
        System.out.println(" ");
        System.out.println("Here is your EDEKA shopping list!");
        System.out.println(" ");
        System.out.println("\t" + "Qty" + "\t\t" + "\t--\t" + "\t\t" + "Product");
        System.out.println(" ");
        foodOutput();
        hygieneOutput();
        otherOutput();
        drinkOutput();
        System.out.println(" ");
        System.out.println("########################################");
    }
    public static void aldi (){
        System.out.println("########################################");
        System.out.println(" ");
        System.out.println("Here is your ALDI shopping list!");
        System.out.println(" ");
        System.out.println("\t" + "Qty" + "\t\t" + "\t--\t" + "\t\t" + "Product");
        System.out.println(" ");
        drinkOutput();
        foodOutput();
        hygieneOutput();
        otherOutput();
        System.out.println(" ");
        System.out.println("########################################");
    }
    public static void kaufland (){
        System.out.println("########################################");
        System.out.println(" ");
        System.out.println("Here is your KAUFLAND shopping list!");
        System.out.println(" ");
        System.out.println("\t" + "Qty" + "\t\t" + "\t--\t" + "\t\t" + "Product");
        System.out.println(" ");
        foodOutput();
        otherOutput();
        drinkOutput();
        hygieneOutput();
        System.out.println(" ");
        System.out.println("########################################");
    }

    }

Answer 1

这个怎么样:

private static <T> String arrayListToString(ArrayList<T> list){
    if (list.size() == 0){
        return "empty\n";
    }
    StringBuilder sb = new StringBuilder();
    for(T t : list){
        sb.append(list instanceof ArrayList<String> ? t : Integer.toString(t));
        sb.append('\n');
    }
}

public static void writeFile() throws IOException{
    FileWriter writer = new FileWriter("/Users/c-mon/IdeaProjects/final/src/shoppingList.txt");

    writer.write("foodList\n");
    writer.write(arrayListToString(GrocerieList.foodList));
    writer.write("foodAmount\n");
    writer.write(arrayListToString(GrocerieList.foodAmount));
    writer.write("drinkList\n");
    writer.write(arrayListToString(GrocerieList.drinkList));
    writer.write("drinkAmount\n");
    writer.write(arrayListToString(GrocerieList.drinkAmount));

    writer.close();
}