Question

错误在 indexoutofboundsexception 处 System.out.println(hurricane.get(2));。我该如何解决这个问题，以便我可以打印飓风对象？我尝试了几种不同的方法，但无济于事。我尝试将 null 添加到 hurricane ，但这没有用。它还说索引 2 超出了长度 2 的范围。

import java.util.ArrayList;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.File;
import java.util.Scanner;
public class HurricaneTesterTest

{

  public static void main(String[] args) throws IOException {

    //read data from text file & put in an array
    File fileName = new File("HurricaneData.txt");
    Scanner inFile = new Scanner(fileName);
    int numValues = 0;

    //count number of lines in text file
    while (inFile.hasNextLine()) {
      inFile.nextLine();
      numValues++;
    }
    inFile.close();

    //initialize arrays based on lines counted in text file
    ArrayList < Integer > years = new ArrayList < Integer > ();
    ArrayList < String > months = new ArrayList < String > ();
    ArrayList < Integer > pressures = new ArrayList < Integer > ();
    ArrayList < Double > windSpeeds = new ArrayList < Double > ();
    ArrayList < String > names = new ArrayList < String > ();
    ArrayList < String > Cat1 = new ArrayList < String > ();

    //read and assign data from text file to the arrays
    inFile = new Scanner(fileName);
    int index = 0;
    while (inFile.hasNext()) {
      years.add(inFile.nextInt());
      months.add(inFile.next());
      pressures.add(inFile.nextInt());
      windSpeeds.add(inFile.nextDouble());
      names.add(inFile.next());
      index++;
    }
    inFile.close();

    for (int i = 0; i < windSpeeds.size(); i++) {
      windSpeeds.set(i, windSpeeds.get(i) * 1.151);

      //System.out.println(windSpeeds);
    }

    for (int x = 0; x < windSpeeds.size(); x++) {
      if (windSpeeds.get(x) < 96 && windSpeeds.get(x) > 73) {
        Cat1.add("Category 1");
      }
      if (windSpeeds.get(x) < 111 && windSpeeds.get(x) > 95) {
        Cat1.add("Category 2");
      }
      if (windSpeeds.get(x) < 130 && windSpeeds.get(x) > 110) {
        Cat1.add("Category 3");
      }
      if (windSpeeds.get(x) < 157 && windSpeeds.get(x) > 129) {
        Cat1.add("Category 4");
      }
      if (windSpeeds.get(x) > 156) {
        Cat1.add("Category 5");
      }
    }
    ArrayList < Hurricane > hurricane = new ArrayList < Hurricane > ();

    for (int a = 0; a < hurricane.size(); a++) {
      hurricane.add(null);
    }

    for (int r = 0; r < hurricane.size(); r++) {
      hurricane.add(new Hurricane(years.get(r), names.get(r), months.get(r), Cat1.get(r), pressures.get(r), windSpeeds.get(r)));;
    }
    System.out.println(hurricane.get(2));

  }
}

//create a Hurricane ArrayList using the data above

//user prompted for range of years

//print the data

Answer 1

ArrayList<Hurricane> hurricane = new ArrayList<Hurricane>();

for(int a = 0; a<hurricane.size(); a++){
    hurricane.add(null);
}

for(int r = 0; r<hurricane.size(); r++){
      hurricane.add(new Hurricane(years.get(r),names.get(r),months.get(r),Cat1.get(r),pressures.get(r), windSpeeds.get(r)));;
}

根据这些行，您没有向列表添加任何内容，因为它已初始化为空。请尝试这样的事情：

ArrayList<Hurricane> hurricane = new ArrayList<Hurricane>();

for(int r = 0; r<years.size(); r++){
      hurricane.add(new Hurricane(years.get(r),names.get(r),months.get(r),Cat1.get(r),pressures.get(r), windSpeeds.get(r)));;
}

它应该适用于您的情况。您可能会遇到 Cat1 问题，因为看起来如果块的范围比较错误：cat1(73-96), cat2(95-111) - 重叠。

如何在我的代码中修复此索引错误？

1 个答案: