如何遍历哈希图以获取每个第四个键，值对？

Question

I have a hashmap like this;

key value1
key value2
key value3
key value4
key1 value5
key1 value6
key1 value7
key1 value8
key2 value9
... and so on

Now I want to put this in a ListView which contains four rows , and in row1, I want:

key value1
key1 value5
key2 value9
key3 value13 and so on till end

And in row2, I want:

key value2
key1 value6
key2 value10
key3 value14 and so on till end

And then the same in rows 3 and 4. There are always only 4 rows.

I am having trouble iterating through this. Here is the code I wrote, but it doesn't work.

String[] fourrows = hashMap.get("KEY");
for (int i=0;i<fourrows.length;i++) {
HashMap<String, String> listHashMap = new HashMap<>();
listHashMap.put("TA",  "ROW VALUE "+fourrows[i]);

for (int j=1;j<hashMap.entrySet().size();j+=4) {
String val = hashMap.values().toArray()[j].toString();
String key = hashMap.get(hashMap.keySet().toArray()[0]).toString();

listHashMap.put("IA", key);
listHashMap.put("XA", val);
incmStmtList.add(listHashMap);
}
}

//Then I pass TA, IA and XA to a simple list adapter and add it to a listView.
incmAdapter = new SimpleAdapter(getContext(), incmStmtList,R.layout.content_results, new String[]{"TA", "IA", "XA"},new int[]{R.id.ta, R.id.ia, R.id.tota});
listView.setVerticalScrollBarEnabled(true);
listView.setAdapter(incmAdapter);

Thanks.

Answer 1

Instead of using HashMap use Multimap. And based on key get the value in Collection object. then from each Collection add one one value on all the list.

Multimap myList = ArrayListMultimap.create();

            myList.put("key","value1");
            myList.put("key","value2");
            myList.put("key","value3");
            myList.put("key","value4");
            myList.put("key1","value5");
            myList.put("key1","value6");
            myList.put("key1","value7");
            myList.put("key1","value8");
            myList.put("key2","value9");
            myList.put("key2","value10");
            myList.put("key2","value11");
            myList.put("key2","value12");
            myList.put("key3","value13");
            myList.put("key3","value14");
            myList.put("key3","value15");
            myList.put("key3","value16");

Then get all keys from list

  Set myKeySet = myList.keySet();
  Object[] keys = myKeySet.toArray();

Now you have set of all key. then

    HashMap<String, String> listHashMap1 = new HashMap<>();
    HashMap<String, String> listHashMap2 = new HashMap<>();
    HashMap<String, String> listHashMap3 = new HashMap<>();
    HashMap<String, String> listHashMap4 = new HashMap<>();

Now add the value to every list

  for(int i=0;i<4;i++){
        List<String> keyval = (List)myList.get((String)keys[i]);
        listHashMap1.put((String)keys[i],keyval.get(0));
        listHashMap2.put((String)keys[i],keyval.get(1));
        listHashMap3.put((String)keys[i],keyval.get(2));
        listHashMap4.put((String)keys[i],keyval.get(3));
     }

Now you have set of four row list. This Multimap is using google guava. So you need to implement guava in your gradle as below: implementation 'com.google.guava:guava:26.0-jre'

Answer 2

From the code you supplied it seems that the source hashMap is of type Map<String, String[]> .

You could iterate over the entries of the map, and for each entry store the four values in different result containers. Since you indicated the result containers should be maps as well:

    Map<String, String> one = new HashMap<>();
    Map<String, String> two = new HashMap<>();
    Map<String, String> three = new HashMap<>();
    Map<String, String> four = new HashMap<>();

    hashMap.entrySet().forEach(entry -> {
        String[] values = entry.getValue();
        one.put(entry.getKey(), values[0]);
        two.put(entry.getKey(), values[1]);
        three.put(entry.getKey(), values[2]);
        four.put(entry.getKey(), values[3]);
    });

Note: assuming every key always has exactly four values.