java - 配列の制限

Question

これは以下の私のコードです。java.lang.IndexOutOfBoundsExceptionが発生し、修正できませんか？ファイルに100を超える名前があるので、エラーが発生しないようにする必要があります。

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class ArrayPractice1 {
    public static void main(String[] args) throws FileNotFoundException
    {

        String[] names = new String[100];
        Scanner scan = new Scanner(new File("names.txt"));
        int index = 0;

        while (scan.hasNext()){
            names[index]=(scan.nextLine());
            index++;
        }     
        for(int i = 0; i <index -1; i++){
            System.out.println(names[i]);
        }

    }

}

score 2 · Accepted Answer

youre not working with an ArrayList of Strings, you're working with a plain array of Strings. seems like youre getting more than 100 items from scan.hasNext() and so you eventually try to access names[100] and get the exception you describe
instead, you could use this:

ArrayList<String> names = new ArrayList<String>();

and then

while (scan.hasNext()){
   names.add(scan.nextLine());
}

and you wont have to worry about knowing the exact size beforehand

score 1 · Accepted Answer

If the size of the input is not known at compile time, consider using an ArrayList instead of an array.

Just add the elements to the ArrayList using names.add(scan.nextLine()):

ArrayList<String> names = new ArrayList<String>();
while (scan.hasNext()) {
      names.add(scan.nextLine())
}

score 0 · Accepted Answer

Why not making it independent from any upper limit? Use an ArrayList:

    ArrayList<String> names = new ArrayList<String>();
    Scanner scan = new Scanner(new File("names.txt"));

    while (scan.hasNext()){
        names.add(scan.nextLine());
    }     
    for(String name : names){
        System.out.println(name);
    }

score 0 · Accepted Answer

配列のサイズとして100を指定しています.ファイルに100行を超える行がある場合、間違いなく例外がスローされます

score 0 · Accepted Answer

while ループの条件を次のように変更します。

while (scan.hasNext() && index < 100)

これにより、配列がいっぱいになった後に読み取りループが停止します

java - 配列の制限

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