Question

我一直在为while循环得到这个错误：java.lang.ArrayIndexOutOfBoundsException; 这是：将新数据读入＆＃34; Input.txt＆＃34;的名称数组中。每行一个String，并将它们放在一个数组中。文件中的字符串数必须与数组中的单元格数相同。

    // Open an input textfile named "Input.txt".
    File f = new File("Input.txt");
    Scanner inputFile = new Scanner(f);
    System.out.println("\nThe array contents:");

    // Read new data into the array of names from "Input.txt" one String per line, and places them in an array. 
    //The number of Strings in the file must be the same as the number of cells in the array.
    String[] input = new String [5];

    int k=0;
    while (inputFile.hasNext())
    {
        String str = inputFile.nextLine();
        input[k]=str;
        k++;
    }
    inputFile.close();




    //Print the new array contents on the screen
    PrintWriter pw = new PrintWriter("Input.txt");
    for(String str : array)
        pw.println(str);
    pw.close();

}

/**
 * Method printOnScreen sends the entire contents of an 
 * array to the Screen using an "enhanced for" loop.
 * 
 * @param array the array of Strings be printed on Screen
 * 
 */
public static void printOnScreen(String[] args)
{
    for(String val : args)
        System.out.println(val);
}

Answer 1

你得到ArrayIndexOutOfBoundException，这意味着你的文件有超过5行，而String数组的长度只有5，所以抛出了异常。如果你想从文件'Input.txt'中读取5个名字，那么在k> 5

时打破循环

while (inputFile.hasNext())
{   
    if(k>5) break;
    String str = inputFile.nextLine();
    input[k]=str;
    k++;
}

或者如果要读取整个文件，则需要使用在创建时未定义大小的数组，如动态数组：ArrayList

List<String> input = new ArrayList<String>();

while (inputFile.hasNext())
{
    String str = inputFile.nextLine();
    input.add(str);
}

Answer 2

您的数组大小似乎很短。如果您不确定数组大小，我建议您使用ArrayList。

List<String> input = new ArrayList<String>();

int k=0;
while (inputFile.hasNext())
{
    String str = inputFile.nextLine();
    input.add(str);
}
inputFile.close();

Answer 3

工作示例

public class Test2 {

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

        BufferedReader input = new BufferedReader(new FileReader("d:\\myFile.txt"));

        String str;

        List<String> list = new ArrayList<String>();
        while ((str = input.readLine()) != null) {
            list.add(str);
        }

        String[] stringArr = list.toArray(new String[0]);

        System.out.println("\nThe array contents:");
        for (String val : stringArr)
            System.out.println(val);

    }

}

<强>输出

数组内容：

stack
overflow
is 
good

文字文件输入 myFile.txt

stack
overflow
is 
good

从input.txt读取新数据到名称数组

3 个答案: