Develop Reference

How to save List Of HashMap in android?

I have a hashmap of string
HashMap<String, String> hashMap = new HashMap<>();
hashMap.put("name", name);
hashMap.put("number", number);
hashMap.put("profileImage", image);
and a List of Hashmap
List<HashMap<String, String>> recents = new ArrayList<>();
recents.add(hashMap);
Now I have to save this list
I have tried using https://github.com/pilgr/Paper to save this List
Paper.book().write("recents", recents);
but i can't get the list back
List<HashMap<String, String>> list = Paper.book().read("recents");
HashMap<String,String> hashMap = list.get(0);
String name = hashMap.get("name");
String number = hashMap.get("number");
String image = hashMap.get("profileImage");
Uses of the code
actually I'm passing this list to recycelerViewAdapeter and from there in OnBindViewHolder() I'm getting all the Hashmap values and displaying it to user
Saving Data Code
Paper.init(this);
List<HashMap<String, String>> recents = new ArrayList<>();
HashMap<String, String> hashMap = new HashMap<>();
hashMap.put("name", name);
hashMap.put("number", number);
hashMap.put("profileImage", image);
recents.add(hashMap);
Paper.book().write("recents", contacts);
Receiving Data Code
Paper.init(requireActivity());
recyclerView = view.findViewById(R.id.recyclerView);
List<HashMap<String, String>> list = Paper.book().read("recents");
Adapter = new Adapter(requireActivity(), list);
recyclerView.setAdapter(Adapter);

You can use Gson and SharedPreferences to do the same.
implementation 'com.google.code.gson:gson:2.8.9'
Example:
private SharedPreferences sp;
private HashMap<String, Boolean> favs;
....
....
public void addFavourite(String wall_name) {
favs = getFavourites();
favs.put(wall_name, true);
setFavourties();
}
public void removeFav(String wall_name) {
favs = getFavourites();
favs.put(wall_name, false);
setFavourties();
}
private void setFavourties() {
SharedPreferences.Editor pe = sp.edit();
Gson gson = new Gson();
String j = gson.toJson(favs);
pe.putString("Favourites", j);
pe.apply();
}
public HashMap<String, Boolean> getFavourites() {
Gson gson = new Gson();
String j = sp.getString("Favourites", null);
if (j != null) {
Type stringBooleanMap = new TypeToken<HashMap<String, Boolean>>() {
}.getType();
return gson.fromJson(j, stringBooleanMap);
} else {
return new HashMap<>();
}
}

Group and Aggregate List of Map<String, Object>

I have a List<Map<String, Object>> input like below:
[{
CURRENCY = USD,
STATUS = NEW,
PUBLISH_REGION = DEL,
SOURCE = ALADDIN,
RECON_STATUS = null,
JOB_ID_COUNT = 783
}, {
CURRENCY = USD,
STATUS = IN_PROGRESS,
PUBLISH_REGION = DEL,
SOURCE = ALADDIN,
RECON_STATUS = null,
JOB_ID_COUNT = 462
}, {
CURRENCY = USD,
STATUS = NEW,
PUBLISH_REGION = DEL,
SOURCE = GROUP,
RECON_STATUS = null,
JOB_ID_COUNT = 4
}]
I am trying to create another List<Map<String, Object>> by grouping on CURRENCY, PUBLISH_REGION, SOURCE and RECON_STATUS columns. And add all unique STATUS values as pivot to the output map and use JOB_ID_COUNT to summarize/aggregate the count.
List<String> groups = new ArrayList<>(asList("SOURCE", "RECON_STATUS", "PUBLISH_REGION", "CURRENCY"));
List<Map<String, Object>> = input.stream()
.collect(groupingBy(row -> row.get(groups.get(0)), mapping(map -> map.get(groups.get(0)), toList())));
I am expecting below response:
Output:
[{
CURRENCY = USD,
PUBLISH_REGION = DEL,
SOURCE = ALADDIN,
RECON_STATUS = null,
NEW = 783,
IN_PROGRESS = 462
}, {
CURRENCY = USD,
PUBLISH_REGION = DEL,
SOURCE = GROUP,
RECON_STATUS = null,
NEW = 4,
IN_PROGRESS = 0
}]
I am getting compile time error when trying to group by multiple map fields. Single field groupingBy is working fine. Any help is greatly appriciated.

Without Using Custom Class
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MultipleFieldSorting2 {
private static Map<String, Object> map, map1, map2;
private static List<Map<String, Object>> lst = new ArrayList<>();
static {
map = new HashMap<>();
map.put("CURRENCY", "USD");
map.put("STATUS", "NEW");
map.put("PUBLISH_REGION", "DEL");
map.put("SOURCE", "ALADDIN");
map.put("RECON_STATUS", null);
map.put("JOB_ID_COUNT", "783");
map1 = new HashMap<>();
map1.put("CURRENCY", "USD");
map1.put("STATUS", "IN_PROGRESS");
map1.put("PUBLISH_REGION", "DEL");
map1.put("SOURCE", "ALADDIN");
map1.put("RECON_STATUS", null);
map1.put("JOB_ID_COUNT", "462");
map2 = new HashMap<>();
map2.put("CURRENCY", "USD");
map2.put("STATUS", "NEW");
map2.put("PUBLISH_REGION", "DEL");
map2.put("SOURCE", "GROUP");
map2.put("RECON_STATUS", null);
map2.put("JOB_ID_COUNT", "4");
lst.add(map);
lst.add(map1);
lst.add(map2);
}
public static Map<String, Object> mapper(Map<String, Object> e){
String key = e.get("CURRENCY") + "-" + e.get("PUBLISH_REGION") + "-" + e.get("SOURCE") + "-" + e.get("RECON_STATUS");
Map<String, Object> groupedValue = res.get(key);
if(groupedValue!=null){
groupedValue.put((String) e.get("STATUS"), groupedValue.get("STATUS")!=null ? groupedValue.get("STATUS")+","+e.get("JOB_ID_COUNT") : e.get("JOB_ID_COUNT"));
if(groupedValue.get("NEW")==null){
groupedValue.put("NEW", 0);
}
if(groupedValue.get("IN_PROGRESS")==null){
groupedValue.put("IN_PROGRESS", 0);
}
}else{
groupedValue = new HashMap<>();
res.put(key, groupedValue);
groupedValue.put("CURRENCY", e.get("CURRENCY"));
groupedValue.put("PUBLISH_REGION", e.get("PUBLISH_REGION"));
groupedValue.put("SOURCE", e.get("SOURCE"));
groupedValue.put("RECON_STATUS", e.get("RECON_STATUS"));
groupedValue.put((String) e.get("STATUS"), e.get("JOB_ID_COUNT"));
}
return groupedValue;
}
static Map<String, Map<String, Object>> res = new HashMap<>();
public static void main(String[] args) {
List<Map<String, Object>> finalResult = new ArrayList<>();
lst.stream()
.map(MultipleFieldSorting2::mapper)
.forEach(result -> {
if(!finalResult.contains(result))
finalResult.add(result);
});
System.out.println(finalResult);
}
}

Tried this solution and it is working
Stream the source List
Map each value of map in the list to Class MapWrapper(a pojo where each key is a field)
GroupBy using the groupByKey defined in MapWrapper(uses CURRENCY, PUBLISH_REGION, SOURCE and RECON_STATUS columns)
3.a The result is a Map<String, List<MapWrapper>>
4.Stream through the entry set
map - and get the value alone from (Map<String, List<MapWrapper>>)
Map - convert from List<MapWrapper> to Map<String, Object> using MapWrapper::map
Collect to a list
In Short the solution is
List<Map<String, Object>> value = lst.stream()
.map(map -> new MapWrapper(map))
.collect(groupingBy(MapWrapper::groupByKey))
.entrySet()
.stream()
.map(e -> e.getValue())
.map(MapWrapper::map).collect(toList());
Working Code
public class MultipleFieldSorting {
private static Map<String, Object> map, map1, map2;
private static List<Map<String, Object>> lst = new ArrayList<>();
static {
map = new HashMap<>();
map.put("CURRENCY", "USD");
map.put("STATUS", "NEW");
map.put("PUBLISH_REGION", "DEL");
map.put("SOURCE", "ALADDIN");
map.put("RECON_STATUS", null);
map.put("JOB_ID_COUNT", "783");
map1 = new HashMap<>();
map1.put("CURRENCY", "USD");
map1.put("STATUS", "IN_PROGRESS");
map1.put("PUBLISH_REGION", "DEL");
map1.put("SOURCE", "ALADDIN");
map1.put("RECON_STATUS", null);
map1.put("JOB_ID_COUNT", "462");
map2 = new HashMap<>();
map2.put("CURRENCY", "USD");
map2.put("STATUS", "NEW");
map2.put("PUBLISH_REGION", "DEL");
map2.put("SOURCE", "GROUP");
map2.put("RECON_STATUS", null);
map2.put("JOB_ID_COUNT", "4");
lst.add(map);
lst.add(map1);
lst.add(map2);
}
public static void main(String[] args) {
List<Map<String, Object>> value = lst.stream()
.map(map -> new MapWrapper(map))
.collect(groupingBy(MapWrapper::groupByKey))
.entrySet()
.stream()
.map(e -> e.getValue())
.map(MapWrapper::map).collect(toList());
System.out.println(value);
}
}
class MapWrapper {
private String currency;
private String status;
private String publish;
private String source;
private String recon_status;
private String job_id;
public MapWrapper(Map<String, Object> map) {
this.currency = (String) map.get("CURRENCY");
this.status = (String) map.get("STATUS");
this.publish = (String) map.get("PUBLISH_REGION");
this.source = (String) map.get("SOURCE");
this.recon_status = (String) map.get("RECON_STATUS");
this.job_id = (String) map.get("JOB_ID_COUNT");
}
String groupByKey() {
return new StringBuilder().append(this.getCurrency()).append("-").append(this.publish).append("-")
.append(this.source).append("-").append(this.recon_status).toString();
}
public static Map<String, Object> map(List<MapWrapper> lst){
Map<String, Object> res = new HashMap<>();
res.put("CURRENCY",lst.get(0).getCurrency());
res.put("PUBLISH_REGION",lst.get(0).getPublish());
res.put("SOURCE",lst.get(0).getSource());
res.put("RECON_STATUS",lst.get(0).getRecon_status());
for(MapWrapper m : lst){
res.put(m.getStatus(), m.getJob_id());
}
if(res.get("NEW")==null){
res.put("NEW", 0);
}
if(res.get("IN_PROGRESS")==null){
res.put("IN_PROGRESS", 0);
}
return res;
}
String getCurrency() {
return currency;
}
void setCurrency(String currency) {
this.currency = currency;
}
String getStatus() {
return status;
}
void setStatus(String status) {
this.status = status;
}
String getPublish() {
return publish;
}
void setPublish(String publish) {
this.publish = publish;
}
String getSource() {
return source;
}
void setSource(String source) {
this.source = source;
}
String getJob_id() {
return job_id;
}
void setJob_id(String job_id) {
this.job_id = job_id;
}
String getRecon_status() {
return recon_status;
}
void setRecon_status(String recon_status) {
this.recon_status = recon_status;
}
}

How to fetch all data from sqlite and calculate it one by one

I have 3 items in my Table, and i also use HashMap. So, my table look like this:
WIFI_TABLE
position_id routers values
ssid mac_id mac_id rssi
A AP1 23:xx:xx:xx 23:xx:xx:xx -102
B AP2 12:xx:xx:xx 12:xx:xx:xx -98
C AP3 9a:xx:xx:xx 9a:xx:xx:xx -100
I'm scanning a new data also in HashMap, and it look like this:
SCAN RESULT
position_id routers values
ssid mac_id mac_id rssi
UNKNOWN AP1 23:xx:xx:xx 23:xx:xx:xx -102
AP2 12:xx:xx:xx 12:xx:xx:xx -98
AP3 9a:xx:xx:xx 9a:xx:xx:xx -100
AP4 76:xx:xx:xx 76:xx:xx:xx -108
AP5 b8:xx:xx:xx b8:xx:xx:xx -80
As u can see, the result contain all surrounding data. I want to calculate only the same data.
First is get data from database. Then, If mac_id in scan result is equal to mac_id in database, then calculate scanned rssi - database rssi. for example, scanned mac_id = 23:xx:xx:xx is equal to database AP1 then, result = (-98) - (-102). Then get the second data, calculate it, get result2, also the third data and get the result3.
This is Position_data class:
public class PositionData implements Serializable {
private String name;
public HashMap<String, Integer> values;
public HashMap<String,String> routers;
public PositionData(String name) {
// TODO Auto-generated constructor stub
this.name=name;
values = new HashMap<String, Integer>();
routers = new HashMap<String, String>();
}
public void addValue(Router router,int strength){
values.put(router.getBSSID(), strength);
routers.put(router.getBSSID(),router.getSSID());
}
public String getName() {
return name;
}
public String toString() {
String result="";
result+=name+"\n";
for(Map.Entry<String, Integer> e: this.values.entrySet())
result+=routers.get(e.getKey())+" : "+e.getValue().toString()+"\n";
return result;
}
public HashMap<String, Integer> getValues() {
return values;
}
public HashMap<String, String> getRouters() {
return routers;
}
And this is the activity class:
PositionData positionData = (PositionData) intent
.getSerializableExtra("PositionData");
positionsData=db.getReadings(building);
HashMap<String, Integer> rssi = positionData.getValues();
HashMap<String, Integer> rssi1 = positionsData.get(0).getValues();
HashMap<String, String> dest = positionsData.get(0).getRouters();
int dista = 0;
if (positionData.equals(dest)){
dista = Integer.parseInt(String.valueOf(rssi))-Integer.parseInt(String.valueOf(rssi1));
}
Log.v("dis:", String.valueOf(dista));
Also this is get from database helper class:
public ArrayList<PositionData> getReadings(String building_id) {
HashMap<String, PositionData> positions = new HashMap<String, PositionData>();
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.rawQuery("select distinct * from " + READINGS_TABLE
+ " where building_id='" + building_id + "'", null);
cursor.moveToFirst();
while (cursor.isAfterLast() == false) {
String position_id = cursor.getString(1);
Router router = new Router(cursor.getString(2), cursor.getString(3));
Log.v(cursor.getString(2), cursor.getInt(4) + "");
if (positions.containsKey(position_id)) {
positions.get(position_id).addValue(router, cursor.getInt(4));
} else {
PositionData positionData = new PositionData(
cursor.getString(1));
positionData.addValue(router, cursor.getInt(4));
positions.put(position_id, positionData);
}
cursor.moveToNext();
}
System.out.println("Reading done");
ArrayList<PositionData> result = new ArrayList<PositionData>();
for (Map.Entry<String, PositionData> e : positions.entrySet())
result.add(e.getValue());
return result;
}

how to define hashmap within hashmap using object of other hashmap

HashMap<String, HashMap<String, String>> hm = new HashMap<String, HashMap<String, String>>();
hm.put("Title1","Key1");
for(int i=0;i<2;i++) {
HashMap<String, String> hm1 = new HashMap<String, String>();
hm1.put("Key1","Value1");
}
if i have call Title1 that time they call another hashmap. i want
this type of output
hm<key,value(object hm1)>
hm<key,value)
first hashmap object call second hashmap key

If I correct undestand what you want, use following code
HashMap<String, HashMap<String, String>> hm = new HashMap<>();
HashMap<String, String> hm1 = new HashMap<>();
for(int i=0;i<2;i++) {
hm1.put("Key1","Value1");
}
hm.put("Title1", hm1); // save hm
...
HashMap<String, String> hm2 = hm.get("Title1");
String s = hm2.get("Key1"); // s = "Value1"
OR you can create new class
class HashKey {
private String title;
private String key;
...
// getters, setters, constructor, hashcode and equals
}
and just use HashMap < HashKey, String > hm, for example:
hm.put(new HashKey("Title1", "Key 1"), "Value");
...
String s = hm.get(new HashKey("Title1", "Key 1")); // Value

you can do something likewise,
HashMap<String,HashMap<String,String>> hm = new HashMap<String,HashMap<String,String>>();
HashMap<String,String> hm1 = new HashMap<String,String>();
hm1.put("subkey1","subvalue");
hm.put("Title1",hm1);
HashMap<String,String> newhm = hm.get("Title1");

import java.util.HashMap;
import java.util.Map;
public class MapInMap {
Map<String, Map<String, String>> standards =
new HashMap<String, Map<String, String>>();
void addValues() {
Map<String, String> studentA = new HashMap<String, String>();
studentA.put("A1", "49");
studentA.put("A2", "45");
studentA.put("A3", "43");
studentA.put("A4", "39");
standards.put("A", studentA);
Map<String, String> studentB = new HashMap<String, String>();
studentB.put("B1", "29");
studentB.put("B2", "25");
studentB.put("B3", "33");
studentB.put("B4", "29");
standards.put("B", studentB);
}
void disp() {
for (Map.Entry<String, Map<String, String>> entryL1 : standards
.entrySet()) {
System.out.println("Standard :" + entryL1.getKey());
for (Map.Entry<String, String> entryL2 : entryL1.getValue()
.entrySet()) {
System.out.println(entryL2.getKey() + "/" + entryL2.getValue());
}
}
}
public static void main(String args[]) {
MapInMap inMap = new MapInMap();
inMap.addValues();
inMap.disp();
}
}

Serialize JSON document using Jackson

I am trying to serialize JSON document using Jackson library. Below is my JSON document that I have created by hand. Now I need to serialize this document using Jackson
Example-A
{
"v" : {
"site_id" : 0,
"price_score" : 0.5,
"confidence_score" : 0.2,
"categories": {
"123" : {
"price_score": "0.5",
"confidence_score": "0.2"
},
"321" : {
"price_score": "0.2",
"confidence_score": "0.4"
}
}
}
}
I am able to make this part of JSON document till now with my below code and using Jackson-
Example-B
{
"v" : {
"site_id" : 0,
"price_score" : 0.5,
"confidence_score" : 0.2
}
}
Now, I am not able to understand how do I add the list of categories (as shown in Example-A) portion in my Example-B JSON document with my below code?
public static void main(String[] args) {
Map<String, Object> props = new HashMap<String, Object>();
props.put("site-id", 0);
props.put("price-score", 0.5);
props.put("confidence-score", 0.2);
AttributeValue av = new AttributeValue();
av.setProperties(props);
/**
* this will print out the JSON document like I shown in my Example-B
* but I need to make it look like as in Example-A. I am not sure how
* to achieve that?
*/
System.out.println(av);
// serialize it
try {
String jsonStr = JsonMapperFactory.get().writeValueAsString(attr);
System.out.println(jsonStr);
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
Can anybody help me with that?

Solution 1
In you case you can do it with
Map<String, Object> props = new HashMap<String, Object>();
props.put("site-id", 0);
props.put("price-score", 0.5);
props.put("confidence-score", 0.2);
Map<String, String> category123 = new HashMap<String, String>();
category123.put("price_score", "0.5");
category123.put("confidence_score", "0.2");
Map<String, String> category321 = new HashMap<String, String>();
category123.put("price_score", "0.2");
category123.put("confidence_score", "0.4");
Map<String, Object> categories = new HashMap<String, Object>();
categories.put("123", category123);
categories.put("321", category321);
props.put("categories", categories);
Solution 2:
Or you can simplify it with additional classes, e.g.:
public class Category
{
private String price_score;
private String confidence_score;
public Category(String price_score, String confidence_score)
{
this.price_score = price_score;
this.confidence_score = confidence_score;
}
public Category()
{
}
// getters/setters
}
main method
Map<String, Object> props = new HashMap<String, Object>();
props.put("site-id", 0);
props.put("price-score", 0.5);
props.put("confidence-score", 0.2);
Map<String, Category> categories = new HashMap<String, Category>();
categories.put("123", new Category("0.4", "0.2"));
categories.put("321", new Category("0.2", "0.5"));
props.put("categories", categories);