Tuesday, 13 January 2015

Endless RecyclerView OnScrollListener Example in android


Note:

I have updated this post.Please see the updated post



If you have thousands of records in your database server, rather than getting all records loading at a time, try to load some x number of records in the onscroll event and update the ui,

Example:
If you have 1000 records in the server db, get 50 records first time, if the user reached to the last record in the ui, then again load 50 more records in the onscrolllistener event.

Step: 1
======
In this example, i am using following github code snippet for endless RecyclerView

Credit goes to: WoongBi Kim
https://gist.github.com/ssinss/e06f12ef66c51252563e

Step: 2
======

Now, Create an Activity with RecyclerView in the XML Layout file.

CardViewActivity.java


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package com.pratap.cardviews1;

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;

public class CardViewActivity extends AppCompatActivity {

 private Toolbar toolbar;

 private RecyclerView mRecyclerView;
 private RecyclerView.Adapter mAdapter;
 private LinearLayoutManager mLayoutManager;

 private List<Student> studentList;

 // on scroll

 private static int current_page = 1;

 private int ival = 1;
 private int loadLimit = 10;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  toolbar = (Toolbar) findViewById(R.id.toolbar);

  studentList = new ArrayList<Student>();

  loadData(current_page);

  if (toolbar != null) {
   setSupportActionBar(toolbar);
   getSupportActionBar().setTitle("Android Students");

  }

  mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

  // use this setting to improve performance if you know that changes
  // in content do not change the layout size of the RecyclerView
  mRecyclerView.setHasFixedSize(true);

  mLayoutManager = new LinearLayoutManager(this);

  // use a linear layout manager
  mRecyclerView.setLayoutManager(mLayoutManager);

  // create an Object for Adapter
  mAdapter = new CardViewDataAdapter(studentList);

  // set the adapter object to the Recyclerview
  mRecyclerView.setAdapter(mAdapter);

  mRecyclerView.setOnScrollListener(new EndlessRecyclerOnScrollListener(
    mLayoutManager) {
   @Override
   public void onLoadMore(int current_page) {
    // do somthing...

    loadMoreData(current_page);

   }

  });

 }
// By default, we add 10 objects for first time.
 private void loadData(int current_page) {

  // I have not used current page for showing demo, if u use a webservice
  // then it is useful for every call request

  for (int i = ival; i <= loadLimit; i++) {
   Student st = new Student("Student " + i, "androidstudent" + i
     + "@gmail.com", false);

   studentList.add(st);
   ival++;

  }

 }
 // adding 10 object creating dymically to arraylist and updating recyclerview when ever we reached last item
 private void loadMoreData(int current_page) {

  // I have not used current page for showing demo, if u use a webservice
  // then it is useful for every call request

  loadLimit = ival + 10;

  for (int i = ival; i <= loadLimit; i++) {
   Student st = new Student("Student " + i, "androidstudent" + i
     + "@gmail.com", false);

   studentList.add(st);
   ival++;
  }

  mAdapter.notifyDataSetChanged();
  
 }

}

activity_main.xml


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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <include
        android:id="@+id/toolbar"
        layout="@layout/toolbar" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_margin="5dp"
        android:layout_weight="1"
        android:scrollbars="vertical" />

</LinearLayout>



Step: 3
======
EndlessRecyclerOnScrollListener.java


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package com.pratap.cardviews1;

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

public abstract class EndlessRecyclerOnScrollListener extends
  RecyclerView.OnScrollListener {
 public static String TAG = EndlessRecyclerOnScrollListener.class
   .getSimpleName();

 private int previousTotal = 0;
 private boolean loading = true;
 private int visibleThreshold = 5;
 int firstVisibleItem, visibleItemCount, totalItemCount;

 private int current_page = 1;

 private LinearLayoutManager mLinearLayoutManager;

 public EndlessRecyclerOnScrollListener(
   LinearLayoutManager linearLayoutManager) {
  this.mLinearLayoutManager = linearLayoutManager;
 }

 @Override
 public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
  super.onScrolled(recyclerView, dx, dy);

  visibleItemCount = recyclerView.getChildCount();
  totalItemCount = mLinearLayoutManager.getItemCount();
  firstVisibleItem = mLinearLayoutManager.findFirstVisibleItemPosition();

  if (loading) {
   if (totalItemCount > previousTotal) {
    loading = false;
    previousTotal = totalItemCount;
   }
  }
  if (!loading
    && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
   // End has been reached

   // Do something
   current_page++;

   onLoadMore(current_page);

   loading = true;
  }
 }

 public abstract void onLoadMore(int current_page);
}

Step: 4
======
Now create an adapter for the RecyclerView

CardViewDataAdapter.java


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package com.pratap.cardviews1;

import java.util.List;

import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.CompoundButton.OnCheckedChangeListener;

public class CardViewDataAdapter extends
  RecyclerView.Adapter<CardViewDataAdapter.ViewHolder> {

 private List<Student> stList;

 public CardViewDataAdapter(List<Student> students) {
  this.stList = students;

 }

 // Create new views
 @Override
 public CardViewDataAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
   int viewType) {
  // create a new view
  View itemLayoutView = LayoutInflater.from(parent.getContext()).inflate(
    R.layout.cardview_row, null);

  // create ViewHolder

  ViewHolder viewHolder = new ViewHolder(itemLayoutView);
  return viewHolder;
 }

 @Override
 public void onBindViewHolder(ViewHolder viewHolder, int position) {

  viewHolder.tvName.setText(stList.get(position).getName());

  viewHolder.tvEmailId.setText(stList.get(position).getEmailId());
  
  viewHolder.singlestudent=stList.get(position);

 }

 // Return the size arraylist
 @Override
 public int getItemCount() {
  return stList.size();
 }

 public static class ViewHolder extends RecyclerView.ViewHolder {

  public TextView tvName;
  public TextView tvEmailId;

  public Student singlestudent;

  public ViewHolder(View itemLayoutView) {
   super(itemLayoutView);

   tvName = (TextView) itemLayoutView.findViewById(R.id.tvName);

   tvEmailId = (TextView) itemLayoutView.findViewById(R.id.tvEmailId);
   // Onclick event for the row to show the data in toast
   itemLayoutView.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {

     Toast.makeText(
       v.getContext(),
       "Data : \n" + singlestudent.getName() + " \n"
         + singlestudent.getEmailId(),
       Toast.LENGTH_SHORT).show();

    }
   });

  }

 }

}

cardview_row.xml


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<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    card_view:cardCornerRadius="5dp"
    card_view:cardUseCompatPadding="true" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp" >

        <TextView
            android:id="@+id/tvName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:text="name"
            android:textColor="@android:color/black"
            android:textSize="18sp" />

        <TextView
            android:id="@+id/tvEmailId"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/tvName"
            android:text="email"
            android:textColor="@android:color/black"
            android:textSize="18sp" />
    </RelativeLayout>

</android.support.v7.widget.CardView>


Student.java 

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package com.pratap.cardviews1;

import java.io.Serializable;

public class Student implements Serializable {

 /**
  * 
  */
 private static final long serialVersionUID = 1L;

 private String name;

 private String emailId;

 private boolean isSelected;

 public Student() {

 }

 public Student(String name, String emailId) {

  this.name = name;
  this.emailId = emailId;

 }

 public Student(String name, String emailId, boolean isSelected) {

  this.name = name;
  this.emailId = emailId;
  this.isSelected = isSelected;
 }

 public String getName() {
  return name;
 }

 public void setName(String name) {
  this.name = name;
 }

 public String getEmailId() {
  return emailId;
 }

 public void setEmailId(String emailId) {
  this.emailId = emailId;
 }

 public boolean isSelected() {
  return isSelected;
 }

 public void setSelected(boolean isSelected) {
  this.isSelected = isSelected;
 }

}

ScreenShots:
=========


  


Source Code 
=========

Download Link

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