ConstraintLayout CheatSheet

1. Constraint Parent

<?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"

   xmlns:tools="http://schemas.android.com/tools"

   android:layout_width="match_parent"

   android:layout_height="match_parent"

   tools:context="slider.app.com.constraintapp.MainActivity">

</android.support.constraint.ConstraintLayout>

2. Type of Constraint of current view – Must use of to use margin, padding and more

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:layout_constraintBottom_toBottomOf="@+id/idTv1"

app:layout_constraintEnd_toEndOf="parent"

3. Layout Margin

android:layout_margin="16dp"

or

android:layout_marginStart="16dp"

android:layout_marginTop="16dp"

android:layout_marginBottom="16dp"

android:layout_marginEnd="16dp"

or

android:layout_marginLeft="16dp"

android:layout_marginRight="20dp"

or

android:layout_marginHorizontal="20dp"

android:layout_marginVertical="20dp"

or

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintStart_toEndOf="parent"

app:layout_constraintTop_toTopOf="parent"

app:layout_constraintTop_toBottomOf="parent"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintBottom_toTopOf="@+id/idBottomView"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintEnd_toStartOf="parent"

app:layout_constraintLeft_toLeftOf="@+id/idBottomView"

app:layout_constraintLeft_toRightOf="parent"

app:layout_constraintRight_toRightOf="@+id/idBottomView"

app:layout_constraintRight_toLeftOf="parent"

Note
-
The
designer creates android:layout_marginLeft
when
you move the button, but android:layout_marginStart

4.
Padding 

android:padding="16dp"

android:paddingStart="16dp"

android:paddingTop="16dp"

android:paddingEnd="16dp"

android:paddingBottom="16dp"

android:paddingLeft="16dp"

android:paddingRight="16dp"

android:paddingHorizontal="16dp"

android:paddingVertical="16dp"

android:includeFontPadding="true"

5.
Bias

A.
Horizontal Bias

app:layout_constraintHorizontal_bias="0.3"

app:layout_constraintLeft_toLeftOf="parent"

app:layout_constraintRight_toRightOf="parent"

A.
Vertical Bias

app:layout_constraintVertical_bias="0.8"

app:layout_constraintTop_toTopOf="parent"

app:layout_constraintBottom_toBottomOf="parent"

6.
 layout_editor_absolute position

tools:layout_editor_absoluteY="50dp"

tools:layout_editor_absoluteX="40dp"

7.
Ratio

android:layout_height="0dp"

app:layout_constraintDimensionRatio="1:1"

app:layout_constraintTop_toTopOf="parent"

or

android:layout_width="0dp"

android:layout_height="0dp"

   app:layout_constraintDimensionRatio="H,3:1"

   app:layout_constraintBottom_toBottomOf="parent"

   
app:layout_constraintTop_toTopOf="parent"

8.
Chain Style

<?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">

   <Button

       android:id="@+id/view1"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:text="View
1"

       app:layout_constraintVertical_chainStyle="spread"

       app:layout_constraintTop_toTopOf="parent"

       app:layout_constraintBottom_toTopOf="@+id/view2"

       app:layout_constraintRight_toRightOf="parent"

       app:layout_constraintLeft_toLeftOf="parent"
/>

   <Button

       android:id="@+id/view2"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:text="View
2"

       app:layout_constraintTop_toBottomOf="@+id/view1"

       app:layout_constraintBottom_toTopOf="@+id/view3"

       app:layout_constraintVertical_chainStyle="packed"

       app:layout_constraintRight_toRightOf="parent"

       app:layout_constraintLeft_toLeftOf="parent"
/>

   <Button

       android:id="@+id/view3"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:text="View
3"

       app:layout_constraintTop_toBottomOf="@+id/view2"

       app:layout_constraintBottom_toBottomOf="parent"

       app:layout_constraintVertical_chainStyle="packed"

       app:layout_constraintRight_toRightOf="parent"

       app:layout_constraintLeft_toLeftOf="parent"
/>

</android.support.constraint.ConstraintLayout>

9.
GuideLine

<android.support.constraint.Guideline

   android:id="@+id/guideline"

   android:layout_width="wrap_content"

   android:layout_height="wrap_content"

   app:layout_constraintGuide_begin="192dp"

   android:orientation="vertical"/>

<TextView

   android:id="@+id/max_width_demo_view"

   android:layout_width="0dp"

   android:layout_height="wrap_content"

   app:layout_constraintLeft_toLeftOf="parent"

   app:layout_constraintRight_toRightOf="parent"

   app:layout_constraintRight_toLeftOf="@id/guideline"

   app:layout_constraintTop_toTopOf="parent"

   android:padding="8dp"

   android:text="Text
emulating maxWidth of 192dp" />

<TextView

   android:id="@+id/min_width_demo_view"

   android:layout_width="0dp"

   android:layout_height="wrap_content"

   app:layout_constraintLeft_toLeftOf="parent"

   app:layout_constraintRight_toRightOf="parent"

   app:layout_constraintLeft_toRightOf="@id/guideline"

   app:layout_constraintTop_toBottomOf="@id/max_width_demo_view"

   android:padding="8dp"

    android:text="Text
emulating minWidth of 192dp" />

22

22

22

22

Fragment Precise Tutorial

URL : http://abhiandroid.com/ui/fragment-lifecycle-example-android-studio.html

Fragment means isolated or incomplete part of something.

Android introduced fragments in Android 3.0 (API level 11), primarily to support more dynamic and flexible UI designs on large screens

Some of feature are - 

• Modularity: Dividing complex activity code across fragments for better organization and maintenance.
• Reusability: Placing behavior or UI parts into fragments that can be shared across multiple activities.
• Adaptability: Representing sections of a UI as different fragments and utilizing different layouts depending on screen orientation and size.

Method of Fragment

1. onAttach()

2. onCreate()

3. onCreateView()

4. onViewCreated()

5. onActivityCreated()

6. onStart()

7. onResume()

8. onPause()

9. onStop()

10. onDestroyView()

11. onDestroy()

12. onDetach()

-> LifeCycle method of Fragment

Case 1 : When Activity created and fragment attach.

1. First Activity onCreate() event

2. first Fragment onAttach() event

3. First Activity onAttachFragment() event

4. first Fragment onCreate() event

5. first Fragment onCreateView() event

6. first Fragment onViewCreated() event

7. first Fragment onActivityCreated() event

8. first Fragment onStart() event

9. First Activity onStart() event

10. First Activity onPostCreate() event

11. First Activity onResume() event

12. first Fragment onResume() event

13. First Activity onPostResume() event

Case 2 : When one fragment replace another fragment.

1. First Fragment onPause() event

2. First Fragment onStop() event

3. First Fragment onDestroyView() event

4. First Fragment onDestroy() event

5. First Fragment onDetach() event

6. Second Fragment onAttach() event

7. First Activity onAttachFragment() event

8. Second Fragment onCreate() event

9. Second Fragment onCreateView() event

10. Second Fragment onViewCreated() event

11. Second Fragment onActivityCreated() event

12. Second Fragment onStart() event

13. Second Fragment onResume() event

Case 3 : Remove fragment.

Fragment onPause() event

Fragment onStop() event

Fragment onDestroyView() event

Fragment onDestroy() event

Fragment onDetach() event

-> Fragment Transaction

STATIC

Case 1 : Add static fragment

<fragment

 android:name="slider.app.com.appsfortest.FirstFragment"

 android:id="@+id/idFirstFragment"

 android:layout_width="match_parent"

 android:layout_height="300dp"/>

DYNAMIC

Case 1 : Adding Fragment

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.add(R.id.idContainer, firstFragment);

fragmentTransaction.commit();

ShortCut

getSupportFragmentManager().beginTransaction().add(R.id.idContainer, firstFragment).commit();

Case 2 : Replacing Fragment

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.replace(R.id.idContainer, secondFragment);

fragmentTransaction.commit();

ShortCut

getSupportFragmentManager().beginTransaction().replace(R.id.idContainer, secondFragment).commit();

Case 3 : Remove Fragment

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.remove(secondFragment);

fragmentTransaction.commit();

ShortCut

getSupportFragmentManager().beginTransaction().remove(secondFragment).commit();

-> Fragment to AddToBackStack() method

Definition : Re-attach a fragment after it had previously been detached from the UI with detach(Fragment). This causes its view hierarchy to be re-created, attached to the UI, and displayed.

Parameter - An optional name for this back stack state, or null.

Case 1 : null parameter

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.add(R.id.idContainer, new FirstFragment());

fragmentTransaction.addToBackStack(null);

fragmentTransaction.commit();

Case 2 : With parameter and tag

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.add(R.id.idContainer, new FirstFragment(), "FirstFragment");

fragmentTransaction.addToBackStack("TAG");

fragmentTransaction.commit();

-> Find Fragment By Tag

Fragment fragment = fragmentManager.findFragmentByTag("firstFragment");

-> PopStack/Remove Fragment By Tag

fragmentManager.popBackStack("firstFragment",FragmentManager.POP_BACK_STACK_INCLUSIVE);

-> Hide fragment

Hides an existing fragment. This is only relevant for fragments whose views have been added to a container, as this will cause the view to be hidden.

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.hide(secondFragment);

fragmentTransaction.commit();

-> Show fragment

Shows a previously hidden fragment. This is only relevant for fragments whose views have been added to a container, as this will cause the view to be shown.

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.show(secondFragment);

fragmentTransaction.commit();

-> isAddToBackStackAllowed

Returns true if this FragmentTransaction is allowed to be added to the back stack. If this method would return false, addToBackStack(String) will throw IllegalStateException.

 FragmentManager fragmentManager = getSupportFragmentManager();

 FragmentTransaction fragmentTransaction =   fragmentManager.beginTransaction();

 fragmentTransaction.add(R.id.idContainer, new FirstFragment());

 fragmentTransaction.addToBackStack(null);

 Log.d(tag, "isAddToBackStackAllowed : "+fragmentTransaction.isAddToBackStackAllowed());

 fragmentTransaction.commit();

-> isEmpty

true if this transaction contains no operations, false otherwise.

 FragmentManager fragmentManager = getSupportFragmentManager();

 FragmentTransaction fragmentTransaction =   fragmentManager.beginTransaction();

 fragmentTransaction.add(R.id.idContainer, new FirstFragment());

 fragmentTransaction.addToBackStack(null);

 Log.d(tag, "isAddToBackStackAllowed : "+fragmentTransaction.isEmpty());

 fragmentTransaction.commit();

-> setReorderingAllowed(boolean).

FragmentManager fragmentManager = getSupportFragmentManager();

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

fragmentTransaction.add(R.id.idContainer, new FirstFragment());

fragmentTransaction.addToBackStack(null);

fragmentTransaction.setReorderingAllowed(true);

fragmentTransaction.commit();

22