按特定顺序对ArrayList中的值进行排序

Question

让我先解释一下这个场景:

List<Row> rowValues = new ArrayList<>();

// After adding values into list
At location 0 = [Johnson, 10000]
At location 1 = [Adam, 12000]
At location 2 = [Mike, 11000]
At location 3 = [Johnson, 17000]
At location 4 = [Tony, 10000]

我想column1按升序排列元素,column2按降序排列元素.喜欢:

At location 0 = [Adam, 12000]
At location 1 = [Johnson, 17000]
At location 2 = [Johnson, 10000]
At location 3 = [Mike, 11000]
At location 4 = [Tony, 10000]

我不确定这是否可以通过以下方式实现:

Collections.sort(rowValues); //or
Collections.sort(rowValues, Collections.reverseOrder());

行类,如果有任何意义:

final class Row extends ArrayList<Object> implements Comparable<Row> {

    private int index;
    private Order order;


    Row(int initialCapacity) {
        super(initialCapacity);
        this.index = -1; //-1 indicates that the index has not been set
    }

    Object getSortingValue() {
        if (index == -1) {
            throw new IllegalStateException("Sorting column is unknown");
        } else if (isEmpty()) {
            throw new IllegalStateException("Row is empty");
        }
        return get(index);
    }

   void setSortingColumn(int index) throws IllegalArgumentException {
        if (index < 0) {
            throw new IllegalArgumentException("Invalid sorting index: " + index);
        }
        this.index = index;
    }

    Order getOrder() {
        return order;
    }

    void setOrder(Order order) {
        this.order = order;
    }

    @Override
    public int compareTo(Row row) {
        if (row == null) {
            throw new NullPointerException();
        }
        Object sortValue = getSortingValue();
        if (sortValue instanceof Comparable) {
            return ((Comparable) sortValue).compareTo(row.getSortingValue());
        } else {
            throw new IllegalArgumentException(sortValue + " not type of Comparable");
        }
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Row) {
            Row row = (Row) obj;
            return getSortingValue().equals(row.getSortingValue());
        }
        return false;
    }

    @Override
    public int hashCode() {
        return getSortingValue().hashCode();
    }
}

Answer 1

是的,您可以使用它进行排序Collections.sort(),但是您需要定义自己的Comparator,在第一行较大时定义对象比其他对象大,或者如果它们相等,则第二行更大.