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Simple RecyclerView example with filter option in Android

Hi Guys, Maybe you all are expert in terms of using RecyclerView in android. This blog is simple example for using filter option with RecyclerView adapter. As for now you will instantiate RecyclerView and set the adapter to RecyclerView as following way. RecyclerView list = (RecyclerView) findViewById(R.id.list); list.setLayoutManager(new LinearLayoutManager(this)); list.setHasFixedSize(true); ArrayList&ltNumber&gt numbers = new ArrayList&lt&gt(); String ONEs[] = {"ZERO", "ONE", "TWO", "THREE", "FOUR", "FIVE", "SIX", "SEVEN", "EIGHT", "NINE", "TEN"}; String TENs[] = {"ZERO", "TEN", "TWENTY", "THIRTY", "FOURTY", "FIFTY", "SIXTY", "SEVENTY", "EIGHTY", "NINETY", "HUNDRED"}; String HUNDREDS[] = {"ZERO", "HUNDRED", "TWO HUND...
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Simple ConstraintLayout tutorial in Android.

A ConstraintLayout is a ViewGroup which allows you to position and size widgets in a flexible way.

There are currently various types of constraints that you can use:
  • Relative positioning
  • Margins
  • Centering positioning
  • Circular positioning
  • Visibility behavior
  • Dimension constraints
  • Chains
  • Virtual Helpers objects

In this tutorial we will look about Relative positioning more detailly.

Relative positioning


Relative positioning is one of the basic building block of creating layouts in ConstraintLayout. Those constraints allow you to position a given widget relative to another one. You can constrain a widget on the horizontal and vertical axis:
  • Horizontal Axis: left, right, start and end sides
  • Vertical Axis: top, bottom sides and text baseline
Here is the list of available constraints.
  • layout_constraintLeft_toLeftOf
  • layout_constraintLeft_toRightOf
  • layout_constraintRight_toLeftOf
  • layout_constraintRight_toRightOf
  • layout_constraintTop_toTopOf
  • layout_constraintTop_toBottomOf
  • layout_constraintBottom_toTopOf
  • layout_constraintBottom_toBottomOf
  • layout_constraintBaseline_toBaselineOf
  • layout_constraintStart_toEndOf
  • layout_constraintStart_toStartOf
  • layout_constraintEnd_toStartOf
  • layout_constraintEnd_toEndOf
They all take a reference id to another widget, or the parent (which will reference the parent container, i.e. the ConstraintLayout):
For example 
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <View
        android:id="@+id/view1"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_green_dark"
        app:layout_constraintBottom_toTopOf="@+id/view3"
        app:layout_constraintEnd_toStartOf="@+id/view2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/view2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_orange_dark"
        app:layout_constraintBottom_toTopOf="@+id/view3"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/view1"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/view3"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_blue_dark"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/view1" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Constraint Layout"
        android:textColor="@android:color/holo_red_dark"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
This xml will create following output.

Explaination

    <View
        android:id="@+id/view1"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_green_dark"
        app:layout_constraintBottom_toTopOf="@+id/view3"
        app:layout_constraintEnd_toStartOf="@+id/view2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
this code block indicates the system to align this view's bottom should be top of the view3, End should be start of the view2, Start should be start of the parent layout and Top should be top of the parent layout. 
    <View
        android:id="@+id/view2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_orange_dark"
        app:layout_constraintBottom_toTopOf="@+id/view3"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/view1"
        app:layout_constraintTop_toTopOf="parent" />
this code block indicates the system to align this view's bottom should be top of the view3, End should be end of the parent, Start should be end of the view1 layout and Top should be top of the parent layout. 
    <View
        android:id="@+id/view3"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:background="@android:color/holo_blue_dark"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/view1" />
this code block indicates the system to align this view's bottom should be bottom of the parent, End should be end of the parent, Start should be start of the parent layout and Top should be bottom of the view1. 
    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Constraint Layout"
        android:textColor="@android:color/holo_red_dark"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
this code block indicates the system to align this view's bottom should be bottom of the parent layout , End should be end of the parent layout , Start should be start of the parent layout and Top should be bottom of the parent layout, this is center alignment of the parent vertically and horizontally.

If you want to align center of parent horizontally only, then you should use
  • app:layout_constraintEnd_toEndOf="parent"
  • app:layout_constraintStart_toStartOf="parent"
If you want to align center of parent vertically only, then you should use
  • app:layout_constraintBottom_toBottomOf="parent"
  • app:layout_constraintTop_toTopOf="parent"
And also you can use
  • layout_constraintHorizontal_bias
  • layout_constraintVertical_bias
For example the following will make the left side with a 30% bias instead of the default 50%, such that the left side will be shorter, with the widget leaning more toward the left side 
   <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Constraint Layout"
        android:textColor="@android:color/holo_red_dark"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintHorizontal_bias="0.3"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />



Here is the full video tutorial

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Thank You



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