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java - 在文件 I/O 期间获取 IndexOutOfBoundsException

问题描述

我正在执行一项任务，我必须读取一个包含美国州/领土名称及其人口的 .txt 文件，并将州分配给一个 ArrayList 并将人口分配给另一个（并行）。.txt 文件格式如下

state name,123456
state name,123456

所以名称和整数信息之间的分隔是“，”字符。我编写了以下方法来读取文件：

public static void readFile(ArrayList<String>states, ArrayList<Integer> pops){
  try{
     Scanner read = new Scanner(new File("StatesPop.txt"));

     while(read.hasNext()){ //while there is still content to read
       if(read.hasNextInt()){ //if the next info is an int
         pops.add(read.nextInt()); //read it and add it to the pop list
         if(read.hasNextLine()){ //if there is a next line
           read.nextLine(); //moves to the beginning of the next line
         }
       }
       else{ //if it's not an int, it's a char
         read.useDelimiter(","); //read until hitting a comma
         String name = read.next(); 
         states.add(name); //add to the states names list
       }
    }
    read.close();
 }
 catch(FileNotFoundException fnf){
   System.out.println("File was not found.");
 }
}

我得到的错误方法如下：

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 1 out of bounds for length 1
at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:248)
at java.base/java.util.Objects.checkIndex(Objects.java:372)
at java.base/java.util.ArrayList.get(ArrayList.java:459)
at Main.sortStates(Main.java:75)
at Main.menu(Main.java:174)
at Main.main(Main.java:15)

标签： javaarraylistfile-io

解决方案

public static void readFile(ArrayList<String> states, ArrayList<Integer> pops) {
        try {
            Scanner read = new Scanner(new File("StatesPop.txt"));

            while (read.hasNextLine()) {
                String line = read.nextLine();
                String[] lineSplit = line.split(",");
                states.add(lineSplit[0]);
                pops.add(Integer.valueOf(lineSplit[1]));
            }
            read.close();
        } catch (FileNotFoundException fnf) {
            System.out.println("File was not found.");
        }
    }

    //[state name, state name]

    //[123456, 123456]

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