如何将与哈希图中重复出现的键关联的值相加

问题描述

我想在哈希图中添加相同键的值.例如:

I want to add the values of the same keys in a hashmap. For example:

   ABC --> 123  
   DEF --> 456  
   ABC --> 123  
   XXX --> 111  
   XXX --> 222

应该变成:

   ABC --> 246  
   DEF --> 456  
   XXX --> 333  

这是我目前的代码:

public class Reading {


@SuppressWarnings("unchecked")
public static void main(String[] args) throws IOException {
    //Create hashmap to store the the string and int in the excel sheet
    HashMap<String, Integer> hm = new HashMap<String, Integer>();

    String key = null;
    int value = Integer.MIN_VALUE;
    // String chkeq; // this

    @SuppressWarnings("rawtypes")
    ArrayList list = new ArrayList();

    // File path or EXCEL file
    FileInputStream fos = new FileInputStream(
            "/Users/SG/Desktop/tester.xls");

    // Sheet is the individual sheet that the data is coming from, in this
    // case Sheet1

    try {

        // Put the XLS file into
        HSSFWorkbook workbook = new HSSFWorkbook(fos);

        // Get first sheet from the project
        HSSFSheet sheet = workbook.getSheetAt(0);

        // Go through each row
        Iterator<Row> rowIterator = sheet.iterator();
        while (rowIterator.hasNext()) {


            Row row = rowIterator.next();

            // Go through each column in the rows
            Iterator<Cell> cellIterator = row.cellIterator();
            while (cellIterator.hasNext()) {

                Cell cell = cellIterator.next();

                switch (cell.getCellType()) {
                    case Cell.CELL_TYPE_BOOLEAN:
                        //System.out.print(cell.getBooleanCellValue() + "		");

                        list.add(cell.getBooleanCellValue());
                        break;
                    case Cell.CELL_TYPE_NUMERIC:
                        //System.out.print(cell.getNumericCellValue() + "		");

                        value = (int) cell.getNumericCellValue();
                        list.add(cell.getNumericCellValue());
                        break;
                    case Cell.CELL_TYPE_STRING:
                        //System.out.print(cell.getStringCellValue() + "		");
                        key = cell.getStringCellValue();
                        //chkeq = cell.getStringCellValue();

                       /* for (int i = 0; cellIterator.hasNext(); i++) {
                            if (chkeq == cellIterator.next().getStringCellValue()) {
                                System.out.println("same" + cell.getStringCellValue());

                            }

                        }*/

                        list.add(cell.getStringCellValue());
                        break;
                }

                if (key != null && value != Integer.MIN_VALUE) {
                    hm.put(key, value);
                    key = null;
                    value = Integer.MIN_VALUE;
                }

            }
            //System.out.println("");

        }
        for (String keys : hm.keySet())
            System.out.println(keys + ":" + hm.get(keys));
        fos.close();
        // System.out.println(list);

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}
}

注意:我使用 Apache POI 从 Excel 工作表中提取数据.

Note: I have used Apache POI to extract the data from an Excel sheet.

代码输出如下:

DEF --> 456
ABC --> 123
XXX --> 222

所有这一切都是用相等的键覆盖放入哈希图中的最后一个单元格.

All this is doing is overwriting the last cell that was put into the hashmap with equal key.

有什么方法可以对这些值求和而不是覆盖它们?

Is there any way to sum the values instead of writing over them?

推荐答案

Put 会覆盖地图中的任何内容.

Put overwrites whatever is in the map.

您需要获取映射中键的当前值(如果存在)并将其添加到您要存储的值中.

You need to get the current value in the map for the key (if it exists) and add it to the value you want to store.

if(hm.containsKey(key))
    hm.put(key, value + hm.get(key));
else
    hm.put(key, value);

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