Question

[{TIME21=0, TIME22=2, TIME23=0, TIME12=0, TIME13=1, LOAN_AMT=500, TIME10=0, TIME20=0, TIME11=1, TIME17=0, TIME9=2, TIME16=0, TIME15=0, TIME14=1, TIME5=0, REG_DT=20170517, TIME6=0, TIME19=0, TIME7=0, TIME18=1, TIME8=4, TIME1=0, TIME2=0, TIME3=0, TIME4=0, TIME0=0}, {TIME21=3, TIME22=2, TIME23=3, TIME12=6, TIME13=7, LOAN_AMT=1000, TIME10=8, TIME20=2, TIME11=6, TIME17=6, TIME9=7, TIME16=2, TIME15=7, TIME14=5, TIME5=0, REG_DT=20170517, TIME6=1, TIME19=1, TIME7=3, TIME18=1, TIME8=5, TIME1=0, TIME2=1, TIME3=0, TIME4=0, TIME0=3}]

这是一个列表，表单是List＆gt;，我想对它进行排序让它显示像TIME1，TIME2 ......，我应该怎么做，而这样的TIME1类型是BigDecimal ，这是我的代码，但它不起作用

for (Map<String, Object> dataMap : chartData) {
            List<Object> objs = new ArrayList<Object>();
            for (final Map.Entry<String, Object> entry : dataMap.entrySet()) {
                Collections.sort(chartData,new Comparator<Map<String, Object>>() {
                    @Override
                    public int compare(Map<String, Object> o1, Map<String, Object> o2) {
                        BigDecimal s1 = (BigDecimal) o1.get(entry.getKey());
                        BigDecimal s2 = (BigDecimal) o2.get(entry.getKey());
                        int result = s1.compareTo(s2);
                        if (result < 0) {
                            System.out.println("a < b");
                            return 1;
                        }else {
                            System.out.println("a>b");
                            return -1;
                        }
                    }

                });
            }
        }

Answer 1

要按键对Map进行排序，您必须将地图的条目包装到支持LinkedList等排序的集合中。这是一个例子：

public static <K, V extends Comparable<? super V>> Map<K, V> 
    sortByKey( Map<K, V> map )
{
    List<Map.Entry<K, V>> list =
        new LinkedList<>( map.entrySet() );
    Collections.sort( list, new Comparator<Map.Entry<K, V>>()
    {
        @Override
        public int compare( Map.Entry<K, V> o1, Map.Entry<K, V> o2 )
        {
            return ( o1.getKey() ).compareTo( o2.getKey() );
        }
    } );
}

如您所见List<Map.Entry<K, V>> list包含地图的条目。要将已排序的列表转换为已排序的地图，请使用LinkedHashMap：

Map<K, V> result = new LinkedHashMap<>();
for (Map.Entry<K, V> entry : list)
{
    result.put( entry.getKey(), entry.getValue() );
}
return result;

我该如何排序呢

1 个答案: