Question

我正在创建一个程序来从excel文件中读取数据并将它们存储在表中。但由于我不熟悉Java中的Comparators，因此我很难制作其中一个。这是我的问题，我已经设法将excel文件中的所有数据作为字符串读取并将它们存储在表中。但我的项目是通过升序ID将它们存储在表中。有人可以帮我创建一个Comparator来比较LinkedHashmaps并用它们的ID存储它们吗？我必须存储的数据如下：

ID  Name    Salary         
50  christine   2349000        
43  paulina 1245874        
54  laura   4587894

解析数据的代码如下：

private static LinkedHashMap parseExcelColumnTitles(List sheetData) {

    List list = (List) sheetData.get(0);
    LinkedHashMap < String, Integer > tableFields = new LinkedHashMap(list.size());
    for (int j = 0; j < list.size(); j++) {
        Cell cell = (Cell) list.get(j);
        tableFields.put(cell.getStringCellValue(), cell.getCellType());
    }

    return tableFields;

}

private static LinkedHashMap[] parseExcelColumnData(List sheetData) {

    LinkedHashMap[] tousRows = new LinkedHashMap[sheetData.size() - 1];
    for (int rowCounter = 1; rowCounter < sheetData.size(); rowCounter++) {

        List list = (List) sheetData.get(rowCounter);

        LinkedHashMap < String, Integer > tableFields = new LinkedHashMap(list.size());
        String str;
        String[] tousFields = new String[list.size()];

        int i = 0;

        for (int j = 0; j < list.size(); j++) {
            Cell cell = (Cell) list.get(j);
            if (cell != null) {
                if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
                    tableFields.put(String.valueOf(cell
                        .getNumericCellValue()), cell.getCellType());
                } else if (cell.getCellType() == Cell.CELL_TYPE_STRING) {
                    tableFields.put(cell.getStringCellValue(), cell
                        .getCellType());
                } else if (cell.getCellType() == Cell.CELL_TYPE_BOOLEAN) {
                    tableFields.put(String.valueOf(cell
                        .getBooleanCellValue()), cell.getCellType());
                }
            }

        }
        tousRows[rowCounter - 1] = tableFields;
    }

    return tousRows;

}

Answer 1

您可以使用TreeMap代替LinkedHashMap，因为您不想保留插入顺序，而排序TreeMap是更好的选择。请阅读此内容Java TreeMap Comparator

Answer 2

你可以做这样的模型：

public class Salary implements Comparable<Salary> {
    private Long id;
    private String name;
    private Double salary;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Double getSalary() {
        return salary;
    }

    public void setSalary(Double salary) {
        this.salary = salary;
    }

    @Override
    public int compareTo(Salary o) {
        if (o.getId() < this.id) {
            return -1;
        } else if (o.getId() > this.id) {
            return 1;
        }
        return 0;
    }
}

然后，您可以使用Collections.sort(list)订购LinkedHashMap

LinkedHashMap的比较器

2 个答案: