如何将数据从excel存储到ArrayList<ArrayList<String>> [英] How to store data from excel to ArrayList&lt;ArrayList&lt;String&gt;&gt;

问题描述

我有这样的 excel 数据

I have data from excel like this

111 | 222 | 333 | 444 | 555 | 666
11  | 12  | 13  | 14  | 15  | 16
1   | 2   | 3   | 4   | 5   | 6
a   | b   | c   | d   | e   | f

我的代码是这样的

public static void main(String[] args) {
    try {
        FileInputStream file = new FileInputStream(new File("xxx"));
        XSSFWorkbook wb = new XSSFWorkbook(file);
        XSSFSheet sheet = wb.getSheetAt(0);

        DataFormatter formatter = new DataFormatter();

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

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

        for (int rowNum = 0; rowNum < sheet.getLastRowNum() + 1; rowNum++) {

            String val = null;

            Row r = sheet.getRow(rowNum);

            for (int i = 0; i < r.getLastCellNum() + 1; i++) {
                Cell cell = r.getCell(i);
                val = formatter.formatCellValue(cell);

            }
            al.add(val);
            mainArrayList.add(al);
        }

        System.out.print(mainArrayList);

    } catch (

    Exception e) {
        e.printStackTrace();
    }
}

输出:[[, , , ], [, , , ], [, , , ], [, , , ]]

我想要的结果是这样的

[[111, 222, 333, 444, 555, 666, ],[11, 12, 13, 14, 15, 16, ],[1, 2, 3, 4, 5, 6, ],[a, s, d, f, g, h, ]]

我相信这是因为al.add(val); 是 null 但我不知道该怎么做才能将 val 添加到 arraylist阿尔.帮助?

I believe it is becauseal.add(val); is null but I don't know how to do in order for me to add the val into arraylist al. help?

推荐答案

首先你需要移动 ArrayListal = new ArrayList(); 转化为 for (int rowNum = 0; rowNum .al 现在需要在每个循环中都是新的.

First you need move ArrayList<String> al = new ArrayList<String>(); into for (int rowNum = 0; rowNum < sheet.getLastRowNum() + 1; rowNum++) {}. al needs to be new in each loop now.

其次，您需要将 al.add(val); 移动到 for (int i = 0; i < r.getLastCellNum() + 1; i++) {}.因为在循环中，val 是正确的值.

Second, you need move al.add(val); into for (int i = 0; i < r.getLastCellNum() + 1; i++) {}. Because in the loop, the val is the right value.

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

    for (int rowNum = 0; rowNum < sheet.getLastRowNum() + 1; rowNum++) {

        String val = null;

        Row r = sheet.getRow(rowNum);

        for (int i = 0; i < r.getLastCellNum() + 1; i++) {
            Cell cell = r.getCell(i);
            val = formatter.formatCellValue(cell);

        }
        al.add(val);
        mainArrayList.add(al);
    }

改成这个

    for (int rowNum = 0; rowNum < sheet.getLastRowNum() + 1; rowNum++) {
        ArrayList<String> al = new ArrayList<String>();
        String val = null;

        Row r = sheet.getRow(rowNum);

        for (int i = 0; i < r.getLastCellNum() + 1; i++) {
            Cell cell = r.getCell(i);
            val = formatter.formatCellValue(cell);
            al.add(val);
        }

        mainArrayList.add(al);
    }

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