如何在哈希图中求和与重复出现的键相关联的值 [英] How can I sum the values associated with a reoccurring key in a hashmap

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

应成为:

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

这是我到目前为止的代码:

Here's the code I have so far:

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() + "\t\t");

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

                        value = (int) cell.getNumericCellValue();
                        list.add(cell.getNumericCellValue());
                        break;
                    case Cell.CELL_TYPE_STRING:
                        //System.out.print(cell.getStringCellValue() + "\t\t");
                        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:我已使用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.

代码输出以下内容:

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

这一切都是用相等的键覆盖被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.

有什么方法可以将这些值相加而不是覆盖它们?

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

推荐答案

放置会覆盖地图中的所有内容.

Put overwrites whatever is in the map.

您需要在映射中获取键的当前值(如果存在)并将其添加到要存储的值中.

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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