Develop Reference

To remove key from hashmap and rearrange keys when used in recycler view

Please any one can help how to remove particular key from hashmap and then rearrange the keys in hashmap accordingly.
Below is my code.
Set<Integer> integerSet = hashMap.keySet();
int removekey = pos;
ArrayList<Integer> integers = new ArrayList<>();
for (Integer integer : integerSet) {
if (integer > removekey) {
integers.add(integer);
}
}
for (Integer integer : integers) {
if (hashMap.containsKey(integer)) {
AddCardPojo pojo = hashMap.get(integer);
pojo.setImagCard(cardImage[integer - 1]);
hashMap.remove(integer);
hashMap.put(integer - 1, pojo);
}
}[![enter image description here][1]][1]
I have attached screenshot of error

You can directly remove a key value pair,you can directly do
hashMap.remove(removeKey);
as for 're arranging keys in hashmap',
it is a data structure which makes no guarantees of order of data.
Check this answer for more
If you need a particular order as per integer, you could use arraylist

Finally it could be done.
Below is my answer.
hashMap.remove(key);
List<AddCardPojo> hashMapsList=new ArrayList<>();
Iterator it = hashMap.entrySet().iterator();
while (it.hasNext()) {
Map.Entry pair = (Map.Entry)it.next();
hashMapsList.add((AddCardPojo) pair.getValue());
}
hashMap = new HashMap<>();
for(int i=0; i<hashMapsList.size();i++){
hashMap.put(i,hashMapsList.get(i));
}

Parsing JsonObject's fields regardless of their name

I've been looking for this for a while now, but couldn't find it anywhere in SO or in the docs.
I am using Gson to parse a json file, and suppose the file is:
{
"animal":"cat",
"paws":"4",
"eyes":"2"
}
Now, since all the fields are strings, I want to parse it as an array of strings, I want something like:
{"cat","4","2"}
And I would like to parse the JsonObject regardless of the name of its tags, and that's where the problem lies. I can garantee the json will contain only strings, but I have no clue of what the fields are going to be named.
Anyone ever faced this problem ? Any help is much appreciated, and any research direction also.
Edit
From the anwers, I managed to do it like this:
for (Map.Entry<String, JsonElement> entry : object.entrySet()) {
// do your stuff here
}
as explained in this answer

JSONObject has the keys() method that returns an Iterator<String>. Through the iterator you can retrieve the value associated with each key. Here the documentation
EDIT:
Since you are using GSON , you can retrieve the keys through the method entrySet()

You should use Iterator, which you can get by calling .keys() on your JSONObject. I think something like that should work (using org.json library):
String[] output = new String[jsonObject.length()];
Iterator iterator = jsonObject.keys();
int i = 0;
while (iterator.hasNext()){
output[i++] = jsonObject.optString((String) iterator.next());
}
EDIT Ok, in case of GSON it will be like this:
Set<Map.Entry<String, JsonElement>> set = jsonObject.entrySet();
String[] out = new String[set.size()];
int i = 0;
for (Map.Entry<String, JsonElement> x : set){
out[i++] = x.getValue().toString();
}

If you are using gson then simple solution is :
Type mapType = new TypeToken<Map<String, String>>(){}.getType();
Map<String, String> map = gson.fromJson(YOUR_JSON_STRING, mapType);
// get only values from map
Collection<String> values = map.values();
for (String string : values) {
// do your stuff here
}
result values collection contains
[cat, 4, 2]

JSONObject jsonObject = new JSONObject(parentJson.getJSONObject("objectname")
.toString());
Iterator<?> iter = jsonObject.keys();
while (iter.hasNext()) {
String key =(String) iter.next();
String value = jsonObject.getString(key);
}

Android: I have an array of HashMaps, how to find a particular HashMap entry given a key that is within one of the HashMap entries?

I have an array of HashMaps, how to find a particular HashMap entry given a key that is within one of the HashMap entries?
For example, I have this:
ArrayList<HashMap<String, String>> bathroomList = new ArrayList<HashMap<String, String>>();
I also know a key within one of the array entries I want to find:
String selectedKey = ((TextView) view.findViewById(R.id.key)).getText().toString();
How do I iterate the array to find it?
Any help appreciated.

A map is a dictionary. For each key, it has one and only one entry. And there's no point in iterating over a map to find a key, since the whole point af a map is to be able to get the entry for a key in a single method call (O(1) for a HashMap):
String value = map.get(selectedKey)
will get you the value associated with selectedKey in the map.

You want something like a regular for loop to iterate over the arraylist and then just check for null You cannot iterate over a hashmap but if you look for a key and it is not there then it will just return null.
ArrayList< HashMap< String, Object>> bathroomList; //this must be initialized.
public String getEntry(String key) {
int count = bathroomList.length(); // this might be size i can never
// remember
String result = null;
for (int i = 0; i < count; i++) {
result = ((String) bathroomList[i].get(key));
if (result != null) {
break;
}
}
if(result == null){
result = "Key Not Found";
}
return result;
}
Edit to map hashmaps.
public HashMap<String, String> getData(String key) {
String[] hashmapKeys = {"key1", "key2", "key3"};
if(key.equals("key1"){
return bathroomList[0];
}
if(key.equals("key2"){
return bathroomList[1];
}
if(key.equals("key3"){
return bathroomList[2];
}
}
Might i suggest using a different data structure. If you already know that you are maping things with keys then instead of an ArrayList< HashMap< String, String > > you could use a HashMap< String, HashMap<String, String>>
HashMap< String, HashMap<String, String>> bathroomList;
then to get your dataset use
HashMap<String, String>> dataSelected =bathroomList.get(selectedKey);`
Most of the time when you pick something out of a list you will use the arraylist because you pass in the position of the list that the user clicked on. The position in the list is what determines what data was selected anyways.

How to use Dictionary (like iphone NSDictionary) in android?

I have worked in soap message, and to parse the value from Webservice, the values are stored in ArrayList.
Example:
values are Employee name (Siva) and Employee id (3433fd), these two values are stored in arraylist, but I want to stored in Dictionary, How?

you can use HashMap like this
Map <String,String> map = new HashMap<String,String>();
//add items
map.put("3433fd","Siva");
//get items
String employeeName =(String) map.get("3433fd");

You can use Bundle.
as it offers String to various types of Mapping.
Bundle b = new Bundle();
b.putInt("identifier", 121);
b.putString("identifier", "Any String");
b.putStringArray("identifier", stringArray);
int i = b.getInt("identifier");
...

public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
EditText textview = (EditText) findViewById(R.id.editTextHash);
EditText textviewNew = (EditText) findViewById(R.id.editTextHash2);
Map<String, String> map = new HashMap<String,String>();
map.put("iOS", "100");
map.put("Android", "101");
map.put("Java", "102");
map.put(".Net", "103");
String TextString = "";
// Set<E> keys = map.keySet();
Set keys = map.keySet();
System.out.println("keys "+keys);
for (Iterator i = keys.iterator(); i.hasNext();)
{
String key = (String) i.next();
System.out.println("key "+key);
String value = (String) map.get(key);
System.out.println("value "+value);
textview.append(key + " = " + value);
TextString+=(key + " = " + value);
}
//textviewNew.setText(TextString);
// Iterator iterator = map.keySet().iterator();
//
// while (iterator.hasNext())
// {
// String object = (String) iterator.next();
// textview.setText(object);
// }
//
// //textview.setText(map.get("Siva"));
//
// System.out.println(map);
}
}

A Dictionary is an abstract class that maps keys to values and there is Dictionary Class in android refer link you can find a note at Class Overview
Do not use this class since it is obsolete. Please use the Map
interface for new implementations.
An attempt to insert either a null key or a null value to a dictionary will result to a NullPointerException,but you can use Map interface,it provides the exact same functionality of a dictionary.you can use it as bellow
//put values
Map Message = new HashMap();
Message.put("title", "Test message");
Message.put("description", "message description");
Message.put("email", "email#gmail.com");
//get values
Log.d("get Message","Message title -"+Message.get("title"));
you can also use A custom class as below
public class MessageObject {
String title;
String description;
String email;
}
you can use Getters and Setters to get and put values,not needed to remember the key names every time you may get some other advantages by this way.

How can i loop thorugth a HashTable keys in android?

I have a hashtable filled with data, but I don't know the keys
How can I loop througth a HashTable keys in android?
I'm trying this, but it doesnt work:
Hashtable output=new Hashtable();
output.put("pos1","1");
output.put("pos2","2");
output.put("pos3","3");
ArrayList<String> mykeys=(ArrayList<String>)output.keys();
for (int i=0;i< mykeys.size();i++){
txt.append("\n"+mykeys.get(i));
}

Use enumeration to traverse over all the values in the table.
Probably this is what you would want to do:
Enumeration e = output.keys();
while (e.hasMoreElements()) {
Integer i = (Integer) e.nextElement();
txt.append("\n"+output.get(i));
}

You should use Map<String, String> instead of Hashtable, and the for-each notation for iteration whenever possible.
Map<String, String> output = new HashMap<String, String>();
output.put("pos1","1");
output.put("pos2","2");
output.put("pos3","3");
for (String key : output.keySet()) {
txt.append("\n" + key);
}
Your current code doesn't work because Hashtable.keys() returns an Enumeration, but you try to cast it to ArrayList which is not assignable from Enumeration.