Sometimes in our android apps need a marquee text effect like smooth autoscroll horizontally or vertically.

For breaking news app there is a most necessary functionality which is show the breaking news like a horizontal scroll.
Again, In share market app in top app should give a auto scroll effect for show the text.

Stock exchange scroll:

But in android there is no perfect library for marquee text but in this article I will give a simplest solution for marquee text.

Add RecyclerView as your desire place and also add dependency in gradle.

<android.support.v7.widget.RecyclerView 
    android:id="@+id/rec_all_stocks" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:scrollbars="vertical" 
    android:layout_alignParentLeft="true" 
    android:layout_alignParentStart="true"></android.support.v7.widget.RecyclerView> 
    

compile 'com.android.support:recyclerview-v7:24.2.0' 

Create adapter for RecyclerView. If you don't know how to create adapter please follow this link: Click Here

For RecyclerView we have to use LayoutManager there is a method which is :

LinearLayoutManager linearLayoutManager = new   LinearLayoutManager(MainActivity.this); 
linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL); 

Then use this in RecyclerView :

    yourRecyclerView.setLayoutManager(linearLayoutManager ); 

Then your RecyclerView will srolled in horizontally.

Here I use a thread which will perform autoscroll the items of RecyclerView. There is a method in RecyclerView which is smoothScrollToPosition() which take position of recyclerview to scroll that position to current position. So I use a thread to increment the position automatically so an autoscroll is happening because position is incremented automatically. When all incremented position will equal to the total item size then start from beginning. In this way an autoscroll effect is happened.
Here is the code :

public void autoScroll(){ 
    final int speedScroll = 0; 
    final Handler handler = new Handler(); 
     final Runnable runnable = new Runnable() { 
           int count = 0; 
           @Override 
           public void run() { 
           if(count == scrollStockAdapter.getItemCount()) 
           count =0; 
           if(count < scrollStockAdapter.getItemCount()){ 
               rec_scroll_stock.smoothScrollToPosition(++count); 
               handler.postDelayed(this,speedScroll); 
           } 
       } 
    }; 
    handler.postDelayed(runnable,speedScroll); 
} 

Now main problem is auto scroll speed which is too fast. For RecyclerView we have to declare a LayoutManager. In LayoutManager there is a method which is smoothScrollToPosition() which is responsible for smooth scrolling. But for scrolling there is a velocity which default speed is 25f. To change this velocity you have to override this method. If you want a smooth scroll then increase this value as you want. In my case I use 4000f.

LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this) { 
    @Override 
    public void smoothScrollToPosition(RecyclerView recyclerView,RecyclerView.State state, int position) { 
    LinearSmoothScroller smoothScroller = newLinearSmoothScroller(MainActivity.this) { 
      private static final float SPEED = 4000f;// Change this value (default=25f) 
      @Override 
      protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) { 
                    return SPEED / displayMetrics.densityDpi; 
          } 
      }; 
      smoothScroller.setTargetPosition(position); 
      startSmoothScroll(smoothScroller); 
      } 
 
};  

Then set this LayoutManager to your RecyclerView like this : yourRecyclerView.setLayoutManager(layoutManager);

In this way you can get a look and feel like Marquee text or like news feed.

Copyright 2016 Ali Ahmed

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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