我如何从哈希图中获取一列值

Question

I have a hashmap listview with four key and multiple value that retrieve from database. For now I can get all the value from the key of FOODID2, FOODNAME2, PRICE2, RATING2 and display via toast. But what I want is just the value from the key (FOODID2) to be display. Is it possible to do it? And correct me if I'm wrong. Thanks!

for (int i=0; i<data.size(); i=i+4)
    {   
        HashMap<String, String> map = new HashMap<String, String>();

        map.put(FOODID2, (String) data.get(i));
        map.put(FOODNAME2, (String) data.get(i+1));
        map.put(PRICE2, (String) data.get(i+2));
        map.put(RATING2, (String) data.get(i+3));

        LIST2.add(map);

        for(Entry<String, String> entry: map.entrySet())
        {
            if(entry.getKey().equals(FOODID2))
            {
                Toast.makeText(getApplicationContext(),
                "EXISTS "  + entry.getKey(), Toast.LENGTH_LONG)
                .show();
            }
        }   
    }

Answer 1

您可以循环map.keySet()获取所有键，循环map.values()获取所有值。

Answer 2

Why not just map.get(FOODID2) ? That is, something like this...

StringBuilder sb = new StringBuilder();
for (HashMap<String, String> map : LIST2) {
  if (sb.length() > 0) {
    sb.append(", ");
  }
  sb.append("EXISTS " + map.get(FOODID2));
}

Answer 3

get entry.getKey() and just validate this if(entry.getKey().equls("YOUR KEY NAME")) { // here u can print the toaste. }

Answer 4

you can use hashMap.get(key) to get the value of a particular key. or in your code you can use a if statement to check for the key.