如何在Java中比较两个哈希图？

Question

I have two hash maps like the following:

1.=============Employee=================


Key : 1_10 : Value : 13/04/2012
Key : 1_11 : Value : 18/04/2012
Key : 1_12 : Value : 19/04/2012
Key : 1_14 : Value : 23/04/2012
Key : 1_13 : Value : 20/04/2012
Key : 1_16 : Value : 25/04/2012
Key : 1_1  : Value : 02/04/2012
Key : 1_15 : Value : 24/04/2012
Key : 1_18 : Value : 27/04/2012
Key : 1_3  : Value : 04/04/2012
Key : 1_17 : Value : 26/04/2012
Key : 1_2  : Value : 03/04/2012
Key : 1_5  : Value : 06/04/2012
Key : 1_19 : Value : 30/04/2012
Key : 1_4  : Value : 05/04/2012
Key : 1_7  : Value : 10/04/2012
Key : 1_6  : Value : 09/04/2012
Key : 1_9  : Value : 12/04/2012
Key : 1_8  : Value : 11/04/2012

2.=============Working day=================

Key : 27 : Value : 27/4/2012
Key : 02 : Value : 02/4/2012
Key : 26 : Value : 26/4/2012
Key : 19 : Value : 19/4/2012
Key : 11 : Value : 11/4/2012
Key : 04 : Value : 04/4/2012
Key : 30 : Value : 30/4/2012
Key : 06 : Value : 06/4/2012
Key : 13 : Value : 13/4/2012
Key : 09 : Value : 09/4/2012
Key : 03 : Value : 03/4/2012
Key : 23 : Value : 23/4/2012
Key : 20 : Value : 20/4/2012
Key : 16 : Value : 16/4/2012
Key : 10 : Value : 10/4/2012
Key : 18 : Value : 18/4/2012
Key : 25 : Value : 25/4/2012
Key : 17 : Value : 17/4/2012
Key : 12 : Value : 12/4/2012
Key : 24 : Value : 24/4/2012
Key : 05 : Value : 05/4/2012

Keys are not same but the values are same and sometime the values are not same.

i want to find out the value which are not present in employeemap when comparing with workingdaymap

if (!employeeMap.containsValue(workingdayMap.get(wKey))) {
    //take the value which is not present in employeeMap which is present in workingdayMap
}

but it gives me null from employeeMap.

Could you please help me to solve this?

Regards Tony

Answer 1

Are the Values Date objects? If so you're attempting to see if the map contains the same object (well its hash, which will be different unless you stored the EXACT same instance in both maps) rather than the value of the object.

Answer 2

Something like this should work:

Set workingValues = new HashSet(workingdayMap.values());
workingValues.removeAll(employeeMap.values());

We get all the values out of workingdayMap using the values() method. We don't want to modify this Collection directly as this will modify workingdayMap so we create a Set of our values called workingValues .

We then remove all the values found in employeeMap which will leave the values which are in workingdayMap but not in employeeMap in workingValues .

Answer 3

Can you please try like this.

    HashMap<String, Date> employeeMap = new HashMap<String, Date>();

    HashMap<String, Date> workingdaymap = new HashMap<String, Date>();

    Set<String> values1 = new HashSet<String>(employeeMap.values());
    Set<String> values2 = new HashSet<String>(workingdaymap.values());
    boolean equal = values1.equals(value2);

Answer 4

below is the code which works perfectly, the reason why the comparison failed is the map value is different .

Key : 27 : Value : 27/4/2012, Key : 1_18 : Value : 27/04/2012

if we see the dates, the difference is clearly seen. 27/4/2012 is different from 27/04/2012 since i stored it as a string.

Iterator<Map.Entry<String,String>> holyDayiterator = workingdayMap.entrySet().iterator();

                 while (holyDayiterator.hasNext()) {
                    Map.Entry holiDayEntry = holyDayiterator.next();
                    if(!employeeMap.containsValue((holiDayEntry.getValue()))){
                        System.out.println("works perfect");
                    }

Thanks guys for your support and people who have gave down vote also.

:) Tony