向ArrayList Java中添加不同大小的数组

Question

null

        static{
        try {   
            Scanner scanner = new Scanner(new FileReader("elements.csv"));
            String title = scanner.nextLine();
            while(scanner.hasNext()){
             
                String[] line = scanner.nextLine().split(",");
                ChemicalElement chemicalElement = new ChemicalElement(line[0],Integer.parseInt(line[1]),line[2],Double.parseDouble(line[3]),Double.parseDouble(line[4]),Double.parseDouble(line[5]),
                        Double.parseDouble(line[6]),Double.parseDouble(line[7]),Double.parseDouble(line[8]));
                chemicalElements.add(chemicalElement);
            }
            
            //(String element, int number, String symbol, double weight, double boil, double melt, double density, double vapour, double fusion)
        } catch (FileNotFoundException ex) {
            System.out.println(ex.getMessage());
        } 
    }

    public ChemicalElement(String element, int number, String symbol, double weight, double boil, double melt, double density, double vapour, double fusion){

        this.number = number;
        this.symbol = symbol;
        this.weight = weight;
        this.boil = boil;
        this.melt = melt;
        this.density = density;
        this.vapour = vapour;
        this.fusion = fusion;
        
    }

和例外情况：

run：线程“main”Java.lang.exceptioninInitializerError at chemistry.chemistry.main(chemistry.Java:30)的chemistry.chemistry.AllElements(chemistry.Java:21)的error由:Java.lang.arrayIndexOutoFboundsexception:6 at chemistry.chemicalElementDAO.(chemicalElementDAO.Java:51)...2多时间：0秒）

Answer 1

试试这个。

• 避免为此使用静态构造函数。
• 创建start()方法以脱离静态上下文
• 然后创建一个包含所有零的数组。
• 读取值并进行适当的转换。
• 用参数调用构造函数。行中未提供的将为零。

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class YourClass {
    
    List<ChemicalElement> chemicalElements = new ArrayList<>();
    
    public static void main(String[] args) {
        YourClass yc = new YourClass();
        // get out of the static context
        yc.start();
    }
    
    public void start() {
        try {
            Scanner scanner =
                    new Scanner(new FileReader("elements.csv"));
            String title = scanner.nextLine();
            
            while (scanner.hasNext()) {
                String[] line = scanner.nextLine().split(",");
                String element = line[0];
                int atno = Integer.parseInt(line[1]);
                String symbol = line[2];
                // Allocates an array for the remainder of the values.
                // This defaults to all zeros.
                // This presumes there will be no more than 9 values
                // per line.       
                double[] values = new double[6];
                for (int i = 0; i < line.length - 3; i++) {
                    values[i] = Double.parseDouble(line[i + 3]);
                }
                
                ChemicalElement chemicalElement = new ChemicalElement(
                        element, atno, symbol, values[0], values[1],
                        values[2], values[3], values[4], values[5]);
                chemicalElements.add(chemicalElement);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}

这是我所能提供的最好的信息。如果它不起作用，你应该和你的老师讨论。