CODEWITHSUNDEEP
javaandroiddictionaryarraylisthashmap
user5212915
user5212915

Reputation:

Compare Hashmap String value and duplicate key for Repeated entry

I am using 

Map<Integer, String> adi = new HashMap<Integer, String>();
for(int u=0; u< sari_nodes.size();u++){
    adi.put(u, sari_nodes.get(u));
}

for (Map.Entry<Integer, String> entry : adi.entrySet()) {
    tv.setText(tv.getText()+"Key : " + entry.getKey()+ " Value : " + entry.getValue()+"\n");
}

My output is :

key: 0 Value : cat
key: 1 Value : dog    
key: 2 Value : car    
key: 3 Value : car    
key: 4 Value : car    
key: 5 Value : car

I want to repeat the key for same entry so that my output looks like 

key: 0 Value : cat    
key: 1 Value : dog    
key: 2 Value : car    
key: 2 Value : car    
key: 2 Value : car    
key: 2 Value : car

How can I perform a check to get these kind of repeated keys?

Can somebody give me some guidance on solving this issue?

thanks.

Upvotes: 1

Views: 857

Answers (3)

Akash Thakare
Akash Thakare

Reputation: 22972

I second the answer of NameSpace.

You want every value to be unique. So, for that you can create a map which add value of your current map as a key. Ultimately we are trying to fetch the same key (first key) for same values. You can do it in a following way.

Map<Integer, String> map = new HashMap<Integer, String>();
map.put(1, "cat");
map.put(2, "dog");
map.put(3, "car");
map.put(4, "cat");
map.put(5, "dog");
map.put(6, "dog");

Map<String, Integer> uniqueValues = new HashMap<>();

for (Entry<Integer, String> entry : map.entrySet()) {
    Integer key = entry.getKey();
    String val = entry.getValue();
    if (uniqueValues.containsKey(val)) {
        key = uniqueValues.get(val);
    }

    uniqueValues.put(val, key);
    System.out.println("Key : " + key + " - Value : " + val);
}

OUTPUT

Key : 1 - Value : cat
Key : 2 - Value : dog
Key : 3 - Value : car
Key : 1 - Value : cat
Key : 2 - Value : dog
Key : 2 - Value : dog

NOTE : Case sensitive, in above code it will consider that Dog and dog both are different.

Upvotes: 1

Bahramdun Adil
Bahramdun Adil

Reputation: 6079

You can try this code below:

Map<Integer, String> adi = new HashMap<>();

adi.put(0, "cat");
adi.put(1, "dog");
adi.put(2, "car");
adi.put(3, "car");
adi.put(4, "car");
adi.put(5, "PC");

int lastKey = 0;
String lasValue = "";
for (Map.Entry<Integer, String> entry : adi.entrySet()) {
    if (!entry.getValue().equals(lasValue)) {
        lastKey = entry.getKey();
    }
    lasValue = entry.getValue();
    //tv.setText(tv.getText()+"Key : " + lastKey+ " Value : " + entry.getValue()+"\n");
    System.out.println("Key : " + lastKey+ " Value : " + entry.getValue());
}

And this is the output:

Key : 0 Value : cat
Key : 1 Value : dog
Key : 2 Value : car
Key : 2 Value : car
Key : 2 Value : car
Key : 5 Value : PC

Upvotes: 0

NameSpace
NameSpace

Reputation: 10177

You would just make a second map, and as you iterate through the elements of the first map, flip the key-value to be the value-key of the second map. If first map's value has already been added to second map as a key, do not overwrite, and output the key-stored-as-a-value in the latter, otherwise output the new key.

Upvotes: 1

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