Develop Reference

How to count json object item?

I'm parsing a JSON string in Android which looks like this:
[
{
"id":70,
"selection":"25"
},
{
"id":71,
"selection":"50"
},
{
"id":72,
"selection":"50"
}
]
Now I want to get the total count of all selection and display it inside a textview. Can anyone give me an example how to do this, or any tutorial about this?
For example:
selection 25 = 1
selection 50 = 2
Thanks for any help!

I think what you're looking for is something like this:
JsonArray selections = new JsonArray(); // This is your parsed json object
HashMap<Integer, Integer> count = new HashMap<>();
for (JsonElement element : selections) {
JsonObject jsonObject = element.getAsJsonObject();
if(jsonObject.has("selection")) {
int selValue = jsonObject.get("selection").getAsInt();
if(count.containsKey(selValue)) {
count.put(selValue, count.get(selValue) + 1);
} else {
count.put(selValue, 1);
}
}
}
What this will do is loop over your json array and get the value of each selection element. To keep track of the count it increments the count inside of the count hashmap.
You can then get the count for a specific value from the hashmap:
count.get(25); // returns 1
count.get(50); // returns 2
// etc...

If you are using Jackson in Java 8, you can first convert the given JSON string to List<Map<String, Object>>, then transform it into List<Integer> for selection. Finally, you can count occurrences in this list as follows:
ObjectMapper mapper = new ObjectMapper();
List<Map<String, Object>> jsonObj = mapper.readValue(jsonStr, new TypeReference<List<Map<String, Object>>>(){});
Map<Integer, Long> counted = jsonObj.stream()
.map(x -> Integer.valueOf(x.get("selection").toString()))
.collect(Collectors.toList())
.stream()
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));
System.out.println(counted.toString());
Console output:
{50=2, 25=1}

ArrayList<String> data = new ArrayList<>();
ArrayList<String> datacount = new ArrayList<>();
jsonStr = "Your JSON"
JSONArray jsonArr= null;
try {
jsonArr = new JSONArray(jsonStr);
for (int i = 0; i < jsonArr.length(); i++) {
JSONObject jsonObj = jsonArr.getJSONObject(i);
//here you can set to TextView
String selection = jsonObj.getString("selection");
//System.out.println("adcac"+selection);
if (data.contains(selection)) {
int index = data.indexOf(selection);
int count = Integer.parseInt(datacount.get(index))+1;
// System.out.println("Index==="+index+"---count---"+count);
datacount.set(index,String.valueOf(count));
} else {
datacount.add(String.valueOf(1));
data.add(selection);
}
// Here you can get data and data count...
// System.out.println("data---"+datacount.toString());
}
} catch (JSONException e) {
e.printStackTrace();
}

you can get the array of the json and iterate and calculate the sum of the selection
JSONArray selections = jsonObj.getJSONArray("selections");
// looping through All Selections
int totalCount = selections.length();

Why doesn't anybody use Json Path to solve this in two lines?

Iterate over ArrayList of ArrayList of Map

I use SimpleExpandableListAdapter to create ExpandableListView for my application. I want to know better how to work with lists and maps and what they are in practice.
//collection for elements of a single group;
ArrayList<Map<String, String>> childDataItem;
//general collection for collections of elements
ArrayList<ArrayList<Map<String, String>>> childData;
Map<String, String> m;
I know how to iterate over ArrayList of Maps, it is not a problem for me, but I got stuck.
childData = new ArrayList<>();
childDataItem = new ArrayList<>();
for (String phone : phonesHTC) {
m = new HashMap<>();
m.put("phoneName", phone);
childDataItem.add(m);
}
childData.add(childDataItem);
childDataItem = new ArrayList<>();
for (String phone : phonesSams) {
m = new HashMap<String, String>();
m.put("phoneName", phone);
childDataItem.add(m);
}
childData.add(childDataItem);
// создаем коллекцию элементов для третьей группы
childDataItem = new ArrayList<>();
for (String phone : phonesLG) {
m = new HashMap<String, String>();
m.put("phoneName", phone);
childDataItem.add(m);
}
childData.add(childDataItem);
And I want to Log what childData contains (<ArrayList<Map<String, String>>), but I don't sure that I did that right. ( 2nd loop is a simple ArrayList of Map iteration)
for (ArrayList<Map<String, String>> outerEntry : childData) {
for(Map<String, String> i:outerEntry ) {
for (String key1 : i.keySet()) {
String value1 = i.get(key1);
Log.d("MyLogs", "(childData)value1 = " + value1);
Log.d("MyLogs", "(childData)key = " + key1);
}
}
for (Map<String, String> innerEntry : childDataItem) {
for (String key : innerEntry.keySet()) {
String value = innerEntry.get(key);
Log.d("MyLogs", "(childDataItem)key = " + key);
Log.d("MyLogs", "(childDataItem)value = " + value);
}
}
}

If you want to log all the elements for childData then there is no need for the last loop, you are already fetching them in the first loop. Please remove below code from the program and it will log all items of childData.
for (Map<String, String> innerEntry : childDataItem) {
for (String key : innerEntry.keySet()) {
String value = innerEntry.get(key);
Log.d("MyLogs", "(childDataItem)key = " + key);
Log.d("MyLogs", "(childDataItem)value = " + value);
}
}
Above loop is iterating over childDataItem and you are using the same reference again and again in your code so in this case above loop will contain only most recent map items.
For simplicity, I changed your log statements to sysout and here's the example and output:
ArrayList<Map<String, String>> childDataItem;
//general collection for collections of elements
ArrayList<ArrayList<Map<String, String>>> childData;
Map<String, String> m;
childData = new ArrayList<>();
childDataItem = new ArrayList<>();
m = new HashMap<>();
m.put("phoneName", "HTC");
m.put("phoneName1", "HTC1");
childDataItem.add(m);
childData.add(childDataItem);
childDataItem = new ArrayList<>();
m = new HashMap<String, String>();
m.put("phoneName", "Samsung");
childDataItem.add(m);
childData.add(childDataItem);
// создаем коллекцию элементов для третьей группы
childDataItem = new ArrayList<>();
m = new HashMap<String, String>();
m.put("phoneName", "LG");
childDataItem.add(m);
childData.add(childDataItem);
for (ArrayList<Map<String, String>> outerEntry : childData) {
for(Map<String, String> i:outerEntry ) {
for (String key1 : i.keySet()) {
String value1 = i.get(key1);
System.out.println("MyLogs (childData)value1 = " + value1);
System.out.println("MyLogs (childData)key = " + key1);
}
}
}
Output
MyLogs (childData)value1 = HTC1
MyLogs (childData)key = phoneName1
MyLogs (childData)value1 = HTC
MyLogs (childData)key = phoneName
MyLogs (childData)value1 = Samsung
MyLogs (childData)key = phoneName
MyLogs (childData)value1 = LG
MyLogs (childData)key = phoneName

So as you probably know, an array list is just a sequential store of data objects. And a map is a key-value pair mapping where the key is used as the lookup and must be unique. That is to say in a Map you may have many duplicate values but only one key.
As for iterating over a Map you can use an entry set which makes it a little easier. So if you wanted to iterate over an object of type <ArrayList<Map<String, String>> it would look something like this for your childDataItem class.
for(Map<String, String> map : childDataItem){
//Take each map we have in the list and iterate over the keys + values
for(Map.Entry<String, String> entry : map){
String key = entry.getKey(), value = entry.getValue();
}
}
And in your other case, the example is the same except you have another layer of array list.
for(List<Map<String, String>> childDataItemList : childData){
for(Map<String, String> map : childDataItemList){
//Take each map we have in the list and iterate over the keys + values
for(Map.Entry<String, String> entry : map){
String key = entry.getKey(), value = entry.getValue();
}
}
}

Create name of a list out of a string

I have a json data, And I want to sort it in java. For every category that is not existing, I want to create a new List. after that or if the category exists, I want to add the data "desc" "title" "link1" and "link2" to it.
if (jsonStr != null) try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray products = jsonObj.getJSONArray("Products");
// looping through All products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
String category = c.getString("category");
String title = c.getString("title");
String desc = c.getString("desc");
String link1 = c.getString("link1");
String link2 = c.getString("link2");
// tmp hash map for single contact
// HashMap<String, String> contact = new HashMap<>();
List<String> Product = new ArrayList<>();
// adding each child node to HashMap key => value
Product.add(category);
Product.add(title);
Product.add(desc);
Product.add(link1);
Product.add(link2);
if (!categories.contains(category)) {
List<List<String>> [category] = new ArrayList<>(); //here I want to create the name of the new list dynamically if it's not existing yet
}
[category].add(Product);
// adding contact to contact list
categories.add([category]); // and finally adding the category to the categories list ( List<List<List<String>>>)
}

You need to add your new category ArrayList to your categories and keep a reference on it. You can use the handy method of get() from the Map to hit two flies with one stone e.g. something like this
List<List<String>> yourCategoryList = null;
if((yourCategoryList = categories.get(category)) == null){
yourCategoryList = new ArrayList<>();
categories.put(category, yourCategoryList );
}
yourCategoryList.add(product);

How to get the keys from a LinkedHasMap?

I have a code populating a listView:
JSONArray data = responseData.getJSONArray("data");
String[] values = new String[data.length()];//I wanna get rid of this
LinkedHashMap<String, String> helpData = new LinkedHashMap();
for (int i = 0; i < data.length() ; i++) {
String header = data.getJSONObject(i).getString("glossary_header");
String description = data.getJSONObject(i).getString("gloassary_description");
helpData.put(header, description);
values[i] = header;
Log.d("mylog", "counter" + i);
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getActivity(),
android.R.layout.simple_list_item_1, values);
setListAdapter(adapter);
I want to pass the keys to Arrayadapter, I was hoping to find a getKeys() method that could magically return an array of key from the map.
KeySet() was close but did not work, what is the proper way to do this. I don't want to use string array. I want to have my pair values together.

You can get like this
Collection<String> values = helpData.keySet();
for (String string : values) {
//
}

Set<String> keys = myArray.keySet();
String[] keysAsArray = keys.toArray(new String[0]);
More detail on the toArray method can be found at http://docs.oracle.com/javase/7/docs/api/java/util/Set.html#toArray(T[])

for (final String key : helpData.keySet()) {
// print data...
}
or
final Iterator<String> cursor = helpData.keySet().iterator();
while (cursor.hasNext()) {
final String key = cursor.next();
// Print data
}

HashMap ArrayList show same value two times in AutoCompleteTextView suggestion

My Code:
// Reading all contacts from database
List<BNICorporateBean> contacts = db.getAllInfo();
// Each row in the list stores country name, currency and email
ArrayList<HashMap<String,String>> aList = new ArrayList<HashMap<String,String>>();
for (BNICorporateBean cn : contacts)
{
if(!memId.trim().equalsIgnoreCase(cn.getBNIMemID().trim()))
{
HashMap<String, String> hm = new HashMap<String,String>();
hm.put("name", cn.getMemName());
hm.put("email", cn.getMemEmail() );
hm.put("mem_id", cn.getBNIMemID());
Log.d("Result", cn._MemName+"\n"+cn._MemEmail+"\n"+cn._BNIMemID);
aList.add(hm);
}
memId= cn.getBNIMemID();
//infoArry.add(cn);
}
// Keys used in Hashmap
//String[] from = { "name","email"};
// Ids of views in listview_layout
//int[] to = { R.id.mem_name,R.id.mem_email};
// Instantiating an adapter to store each items
// R.layout.listview_layout defines the layout of each item
SimpleAdapter adapter = new SimpleAdapter(LoginActivity.this, aList, R.layout.list_member, new String[] { "name","email"},
new int[]{ R.id.mem_name,R.id.mem_email});
/** Setting the adapter to the listView */
autoComplete.setAdapter(adapter);
Takes value from database and my log text show that it returns single value, but don't know why it shows same value two times in list suggestion . Note: for some values it shows once.
I have also print my list and gives perfect result no duplicate values
for(int k=0;k<aList.size();k++)
{
System.out.println(""+aList.get(k));
}

Use it.This may help you
do{
HashMap<String, String> hm = new HashMap<String,String>();
hm.put("name", cn.getMemName());
hm.put("email", cn.getMemEmail() );
hm.put("mem_id", cn.getBNIMemID());
Log.d("Result", cn._MemName+"\n"+cn._MemEmail+" \n"+cn._BNIMemID);
aList.add(hm);
memId= cn.getBNIMemID();
}while(!memId.trim().equalsIgnoreCase(cn.getBNIMemID().trim()));