解决双 Arraylist 添加新值时 Java 堆空间错误

Question

上下文

我有一项任务要求我从文本文件中读取食谱并操作测量单位和成分数量等内容。我已经设法将配方分成三个数组列表，现在必须开始将英制单位转换为公制。但是当我尝试乘以和转换相应的单位时，我得到了 Java 堆空间错误。我在网上查看了如何解决此问题，并意识到这可能与数组列表泄漏内存或使用过多空间有关。问题是我不知道这可能发生在哪里，并且已经尝试使用浮点列表或整数列表而不是双精度，但它仍然没有工作，因为我仍然需要使用小数。我知道字符串转换为 ml 有效，但不知道相应的数字转换是否有效，任何帮助将不胜感激。

代码

import java.util.*;
import java.io.*;
class Main {
    /**
     * Prints methods to user
     */
    public static void main(String[] args) throws Exception{
        servingReader();
        System.out.println(sSize);
        ingrReader();
        System.out.println(ingrList);
        ingrSeperator();
        System.out.println(ingrSeperatorList);
        System.out.println(ingrSeperatorList.get(7));
        divide();
        System.out.println(ingrSeperatorList);
        converter();
        System.out.println(ingrList);
        System.out.print(ingrSeperatorList);
        multiply();
        System.out.print(ingrSeperatorList);
    }//end main

    static int sSize;//int for serving size

    /**
     * Reads text file
     */
    public static void servingReader() throws Exception{

        //recipe read
        File recipe = new File("/home/runner/recipe.txt");
        Scanner sc = new Scanner(recipe);

        //loop to find serving size
        while(sc.hasNextLine()){
            String s = sc.nextLine().toUpperCase();
            if(s.equals("SERVING SIZE")){
                sSize = sc.nextInt();
            }
        }

        sc.close();//scanner closed
    }//servingReader

    static ArrayList<String> ingrList = new ArrayList<>();//ArrayList for ingredients created

    static String scan;

    /**
     * Reads recipe and adds ingredients section to list
     */
    public static void ingrReader() throws Exception{

        //recipe read
        File recipe = new File("/home/runner/recipe.txt");
        Scanner sc = new Scanner(recipe);

        //loop to find ingredients section or recipe
        while(sc.hasNextLine()){
            String s = sc.nextLine().toUpperCase();
            //if scanner finds header INGREDIENTS, section added to ingrList
            if(s.equals("INGREDIENTS")){
                while(sc.hasNextLine()){
                    int i = 0;
                    scan = sc.nextLine();
                    ingrList.add(i, scan);
                    i+= 1;
                    //if nothing is found, breaks
                    if(scan.equals("")){
                        break;
                    }
                }
            }
        }
        sc.close();//scanner closed

        Collections.reverse(ingrList);//reverse method reverses order of elements in ingrList

        int ingr1 = ingrList.size() - 1;
        ingrList.remove(ingr1);

    }//ingrReader

    static ArrayList<Float> ingrSeperatorList = new ArrayList<Float>();//ArrayList for seperated ingredients created

    /**
     * Seperates ingredient quantitys from ingredints list and adds to seperated list
     */
    public static void ingrSeperator(){

        float ingr2 = 0;

        for(int i = 0; i <ingrList.size(); i++){
            String split [] = ingrList.get(i).split(" ");
            ingr2 =  Float.parseFloat(split[0]);
            ingrSeperatorList.add(ingr2);

        }
    }//end ingrSeperator


    /**
     * Gets serving size input from user and then adjusts seperated ingredinets accordingly
     */
    public static void divide() throws Exception{
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your serving size: ");//serving size enetered
        int servingSize = sc.nextInt();

        for(int i=0;i<ingrSeperatorList.size();i++){
            ingrSeperatorList.set(i,ingrSeperatorList.get(i)*servingSize);//origanal quantiys multiplyed by new serving size
        }

        for(int i=0;i<ingrSeperatorList.size();i++){
            ingrSeperatorList.set(i,ingrSeperatorList.get(i)/4);//multiplyed quantitys now didvided by origanal serving size 4
        }
        sc.close();//scanner closed
    }//end divide

问题始于我的转换器方法：

    /**
     * Asks user for choice of units and converts arraylists accorrdingly
     */
    public static void converter() throws Exception{
        Scanner sc = new Scanner(System.in);
/*
        System.out.print("Use imperial or metric: ");//asks user for imperial or metric
        char choice =  sc.next().charAt(0);

        //if user chooses metric
        if((choice == 'a') || (choice == 'A')){*/

        //convert tbsp to ml
        for(int i = 0; i < ingrList .size(); i++){
            //if ingrList contains tbsp replaced with ml
            if(ingrList.get(i).contains("tbsp")){
                ingrList.set(i,ingrList.get(i).replace("tbsp", "ml"));

                for(int j=0;j<ingrSeperatorList.size();j++){
                    ingrSeperatorList.add(ingrSeperatorList.get(j)*15);

                }
            }
        }

        //convert tbsp to ml
        for(int i = 0; i < ingrList .size(); i++){
            //if ingrList contains cup replaced with ml
            if(ingrList.get(i).contains("cup")){
                ingrList.set(i,ingrList.get(i).replace("cup", "ml"));

                for(int j=0;j<ingrSeperatorList.size();j++){
                    ingrSeperatorList.set(j,ingrSeperatorList.get(j)*250);
                }
            }
        }

        //convert tsp to ml
        for(int i = 0; i < ingrList .size(); i++){
            //if ingrList contains tsp replaced with ml
            if(ingrList.get(i).contains("tsp")){
                ingrList.set(i,ingrList.get(i).replace("tsp", "ml"));

                for(int j=0;j<ingrSeperatorList.size();j++){
                    ingrSeperatorList.set(j,ingrSeperatorList.get(j)*5);
                }
            }
        }

    //}
    }//end converter

    /**
     * Gets serving size input from user and then adjusts seperated ingredinets accordingly
     */
    public static void multiply() throws Exception{

        for(int j=0;j<ingrSeperatorList.size();j++){
            ingrSeperatorList.set(j,ingrSeperatorList.get(j)*250);
        }
    }//end divide
}//end main

Answer 1

问题出在这里，当从汤匙转换为毫升时：

for(int j=0;j<ingrSeperatorList.size();j++){
    ingrSeperatorList.add(ingrSeperatorList.get(j)*15);

}

请注意，在其他所有转换中，您都使用ingr.SeperatorList.set，而不是.add。 .add 使您的列表变得更大。您在循环列表时使用了.add，因此无论何时使用.add，列表都会变大，您将永远无法逃脱循环（也就是说，直到空间用完）。