java根据key或value对Map进行排序

根据key排序

java.util包下的TreeMap可以满足此类需求，直接调用TreeMap的构造函数传入我们自己定义的比较器即可

public static Map sortMapByKey(Map map) {
	if (map == null || map.isEmpty()) {
    	return null;
    }

	Map sortMap = new TreeMap(
    	new Comparator() {
        	@Override
            public int compare(String o1, String o2) {
            	return o1.compareTo(o2);
            }});
    sortMap.putAll(map);
	return sortMap;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

根据value排序

原理：将map中所有的entry元素放在list容器中，调用Collections里的静态方法sort(List list, Comparator< super T> c) 进行排序，重新compare方法定义排序规则。为了保证Map中元素与排序后的List中的元素的顺序一致，使用了LinkedHashMap。

public static Map sortMapByValue(Map oriMap) {
        if (oriMap == null || oriMap.isEmpty()) {
            return null;
        }
        Map sortedMap = new LinkedHashMap();
        List> entryList = new ArrayList>(oriMap.entrySet());
        Collections.sort(entryList, new Comparator>() {
            @Override
            public int compare(Entry o1, Entry o2) {

                return o1.getValue().getColumnSortNum() - o2.getValue().getColumnSortNum();
            }
        });

        Iterator> iter = entryList.iterator();
        Entry tmpEntry = null;
        while (iter.hasNext()) {
            tmpEntry = iter.next();
            sortedMap.put(tmpEntry.getKey(), tmpEntry.getValue());
        }
        return sortedMap;
    }
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

ExportExcelColum类

public class ExportExcelColumn {

    private String columnName;

    private Integer columnSortNum;
    public ExportExcelColumn() {

    }
    public String getColumnName() {
        return columnName;
    }
    public void setColumnName(String columnName) {
        this.columnName = columnName;
    }
    public Integer getColumnSortNum() {
        return columnSortNum;
    }
    public void setColumnSortNum(Integer columnSortNum) {
        this.columnSortNum = columnSortNum;
    }
    public ExportExcelColumn(String columnName, Integer columnSortNum) {
        this.columnName = columnName;
        this.columnSortNum = columnSortNum;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25