java - 将 .txt 文件转换为字符串的二维数组列表

Question

这个问题已经有答案了:

What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it? (25 个回答)

已关闭 6 年前。

所以我尝试将 .txt 文件转换为以下格式:

1 2 3 4 
5 6 7 8
9 1 0 1

到字符串的二维数组列表中。这也应该可以与任何其他东西复制，例如

EXTENDING RETRACTING RETRACTING EXTENDING
EXTENDING EXTENDING RETRACTING
RETRACTING

这是我的代码

public class Test {
    public static ArrayList<ArrayList<String>> readFromFile(String path) throws FileNotFoundException{
        @SuppressWarnings("resource")
        Scanner in = new Scanner(new File(path));
        ArrayList<ArrayList<String>> comments= new ArrayList<ArrayList<String>>();
        ArrayList<String> words = new ArrayList<String>();
        String[] line;
        String str;
        String [] values;
        while(in.hasNextLine()){
            str=in.nextLine();
            line = str.split("\t");
            values = line[2].split(" ");
            for(String word : values){
                words.add(word);
            }
        }
        comments.add(words);
        return comments;
        }

    public static void main(String[] args) throws FileNotFoundException{
         ArrayList<ArrayList<String>> inputs = readFromFile("/Users/Jason/yaw.txt");
        int k = 0;
        for(int i = 0; i < inputs.size(); i++){
            for(int j = 0; j < inputs.get(k).size(); j++){
                System.out.print(inputs.get(i).get(j));
                k++;
            }
            System.out.println();
        }
    }
}

目前，它返回此错误。

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 2
    at Test.readFromFile(Test.java:19)
    at Test.main(Test.java:31)

关于如何使其正常工作有任何帮助吗？

Answer 1

这是解决这个问题的一种方法:

    // read file into list
    List<String> linesInFile = Files.readAllLines(Paths.get("filename.txt"));
    // create 2d array based on number of lines
    List<List<String>> array = new ArrayList<>(linesInFile.size());

    // iterate through every line of the file and split the elements using whitespace
    linesInFile.forEach(line -> {
        // get the elements in the current line
        String[] elements = line.split("\\s+");
        // store it in our 2d array
        array.add(Arrays.asList(elements));
    });

    // print every row in our 2d array
    array.forEach(System.out::println);

Files.readAllLines方法将返回一个列表，其中包含文件中的所有行(与您自己的版本类似)。

编辑:转换List<List<String>>进入ArrayList<ArrayList<String>>就像下面这样:

    ArrayList<ArrayList<String>> arrayList = new ArrayList<>();
    array.forEach(row -> arrayList.add(new ArrayList<>(row)));

    System.out.println(arrayList.getClass());
    System.out.println(arrayList.get(0).getClass());

将输出:

    >> class java.util.ArrayList
    >> class java.util.ArrayList