ContactsList | Sectioned Contacts List } { Floating Section Bar | Android library

I am displaying in an activity Contacts from my phonebook in a ListView. I want to add an EditText to search contacts. I have tried 'addTextChangedListener' in 'search_contacts(CharSequence c)' method but I guess I implemented it wrong.

This is 'AddContact' activity to display contacts

I am using Angular material table but the datasource doesn't show any data on my screen. I have a add-person component which loads some data in 'ContactsList: Contacts[];' I use api to return the data to the ContactsList and want to load the data into datasourse in order to show the data on material table, however, there is no data to show up on the screen..

How I can load the data on datasource material table?

add-person.component.ts

I am facing issue of duplicate element when updating the state in useEffect, WHat i am trying to do is I get data from firebase and iterate through the data and updating an array with useState, and if the element already exists in in the array, then skip to add that and move to next element. Codes are below

I'm learning Flutter and there is something I cannot grasp my head around. I implemented a Infinite scroll pagination, with a package (infine_scroll_pagination), it works fine, but the data this Package is getting, comes from a Future call, which takes data from the WEB, and parses it in my Provider Class.

My issue is, the data that is loaded by the Infinite Scroll widget, cannot be accessed, in its state, anywhere else.

Example: Let's take a contact list, that loads 10 contacts at a time:

Background: In my View I have a TextBlock and a TextBox. As soon as the text changes in the TextBox the TextChanged event gets fired and after filtering a list, I want to update the property which is bound to the TextBlock.
In my case it's a counter that shows the number of contacts in the current list.

Problem: When I debug the property (ContactsCount) gets always updated correctly, but only in Code and not in the UI. Strangely enough the UI only updates after I delete the text from the TextBox, to the last list count, but not the actual one.

Code
View:

Here's the template where my button and contactList1 reside:-

I use multiple recyclerview adapters within my app and interface to listen to onclicks. I come to the point where I have 2 fragments which displays the exact same views and exact same data only within another class. But the clickListener within the adapter is bound to the first class so the second class value is not accepted.

This is the code to make more sense.

I am trying to display contacts in Recycler View everything is working fine but contacts are getting displayed twice or thrice.

Here is the Code

I read the latest Firebase Blog which reports firebase now supports not-equal queries. However, it is not working on this android code snippet and I am getting Unresolved reference: where error when using where.