Points To Remember

• Make a class extend Parcelable 
• Make class Serializable

Send Object from one Activity to Another Activity using Serializable

• Activity to send Object
  

  intent.putExtra("name", object);

• Activity to receive object
  

  Object object = (Object) getIntent().getSerializableExtra("name");

Points To Remember

• Ideally splash screen should be shown only at the start on the Android Application.
• Application should not go back to the Splash screen when back button is pressed

How to disable back button to Splash Screen Activity

• Disable the Back Button on the Activity called just after the Splash Screen.
• Remove the Splash Activity from Application life-cycle/history.

@Override
public void onBackPressed() {
}

<activity android:name=".SplashActivity" android:noHistory="true"/>

How to implement Material Design Tab Layout

Step 1 : Add the design dependency in the project

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.0'
    compile 'com.android.support:design:23.1.0'
}

Step 2 : Layout Structure for the activity

--CoordinatorLayout
----AppBarLayout
------TabLayout
----ViewPager

• CoordinatorLayout provides an additional layer of control over the touch events between child views. It is actually a super powered FrameLayout. So we will wrap all our layout inside the Coordinator layout.
• AppBar Layout is used to wrap the TabLayout inside it. It will wrap the Tabs text/heading and will always be a part of the app bar. This allows the tabs to be always visible at the top on vertical scrolling down. If we do not wrap the Tab Layout inside AppBarLayout then we will need to place and adjust its position manually when the pager will scroll vertically.
• TabLayout this layout is the one that will display the tab/pager header/text. If this layout is not added, then the tab headers will not be displayed but the tabs can be still switched by swiping left and right.
• ViewPager this layout is actual implementation of the pages/tabs that can be swiped left and right. It should contain fragment layouts that need to displayed on each tab.

<android.support.design.widget.CoordinatorLayout 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">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabMode="fixed"
            app:tabGravity="fill"/>
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"  />

</android.support.design.widget.CoordinatorLayout>

• app:tabMode="fixed" - it is used when the number of tabs to be displayed can be shown in screen. (fits the screen and scroll is not needed to display all tabs)
• app:tabGravity="fill" - it is used to fill the parent width with the tabs. the tabs will be utilize the width of the parent and will be of same width.

Step 3 : Creating a ViewPagerAdapter to setup ViewPager

package com.ekiras.tab.adapter;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

import java.util.ArrayList;
import java.util.List;

/**
 * @author ekansh 
 */
public class ViewPagerAdapter extends FragmentPagerAdapter {

    private final List<Fragment> fragmentList = new ArrayList<Fragment>();
    private final List<String> titles = new ArrayList<String>();

    public ViewPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        return fragmentList.get(position);
    }

    @Override
    public int getCount() {
        return fragmentList.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return titles.get(position);
    }

    public void addFragment(Fragment fragment, String title){
        fragmentList.add(fragment);
        titles.add(title);
    }

}

Step 4 : Making Fragments to be displayed in ViewPager

• FragOne
• FragTwo

package com.ekiras.tab.fragment;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.ekiras.tab.R;

/**
 * @author ekansh 
 */
public class FragOne extends Fragment{

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_one,container,false);
        return view;
    }

}

package com.ekiras.tab.fragment;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.ekiras.tab.R;

/**
 * @author ekansh 
 */
public class FragTwo extends Fragment{

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_two,container,false);
        return view;
    }

}

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="Fragment One"
        android:textSize="40dp"
        android:textStyle="bold"
        />

</LinearLayout>

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="Fragment Two"
        android:textSize="40dp"
        android:textStyle="bold"
        />

</LinearLayout>

Step 5 : Putting everything together in Activity

package com.ekiras.tab;

import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import com.ekiras.tab.adapter.ViewPagerAdapter;
import com.ekiras.tab.fragment.FragOne;
import com.ekiras.tab.fragment.FragTwo;

/**
 * @author ekansh 
 * 
 * */
public class MainActivity extends AppCompatActivity {

    private ViewPager viewPager;
    private TabLayout tabLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);
        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
    }


    public void setupViewPager(ViewPager viewPager){
        ViewPagerAdapter pagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
        pagerAdapter.addFragment(new FragOne(),"Frag One");
        pagerAdapter.addFragment(new FragTwo(),"Frag Two");
        viewPager.setAdapter(pagerAdapter);
    }




}

• Created a ViewPager adapter to hold the fragments in view pager, these will be used as tabs.
• Created a Tab layout to set the view pager heading and controls.

Points To Remember

Pagination in Custom List View

• We will add 20 items each time to the list view.
• After 18th element is displayed on the screen we will call a method to load new items to the list view, so that user does not wait for new items to be loaded.(In real cases you might be loading from a server and this might take much time).
• We will restrict our pagination after 400 elements have been displayed.( It is a replication of the scenario when the server has no more items to be displayed).

listView.setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView absListView, int i) {

            }

            @Override
            public void onScroll(AbsListView absListView, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if(firstVisibleItem+visibleItemCount > totalItemCount-2 && totalItemCount < maxRecords){
                    personAdapter.add(bootData());
                    personAdapter.notifyDataSetChanged();
                }
            }
        });

Points To Remember

• You need to create a custom List Adapter to show a model class in the list view.
• You need to create a xml file to display, how each item of the list will look on the UI.
• You need to set the Tag in the view, so that your data does not refresh due to scroll.

Create a List View with custom List View Adapter

• Person Model class - show data on UI from this class
• Person Adapter - create the list view and inflate the view
• Main Activity - to contain the list view 

The List View will look like as shown in image below

Points To Remember

• gravity
• layout_gravity

• android:gravity is used for child elements of the view.
• android:gravity_layout is used for this element with respect to parent view.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    >
        <TextView
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:text="EkiRas"
            android:textSize="22dp"
            android:gravity="center"
            />
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:layout_gravity="center"
     >
 // Other Elements
 </LinearLayout>
</LinearLayout>

• outer LinearLayout will set its child elements in center.
• TextView gravity:center will set its ocntent in center.
• inner LinearLayout will be aligned in the center of its parent, that is outer LinearLayout.

Points To Remember

1. VISIBLE - it makes the VIEW visible .
2. INVISIBLE - it makes the VIEW invisible but it still takes the space occupied by the View element on the screen.
3. GONE - it makes the VIEW invisible and also hides the space occupied by the view on the screen.

How to make a TextView Visible

<TextView
    android:id="@+id/text_view_name"
    android:visibility="gone"
    android:layout_height="30dp"
    android:textColor="@android:color/holo_blue_dark"
    android:paddingLeft="15dp"
    android:textStyle="bold"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true"
    android:gravity="center_vertical"
    android:layout_width="match_parent"
    android:background="#e7e7e1"
    xmlns:android="http://schemas.android.com/apk/res/android" />

<TextView
    android:id="@+id/text_view_name"
    android:visibility="invisible"
    android:layout_height="30dp"
    android:textColor="@android:color/holo_blue_dark"
    android:paddingLeft="15dp"
    android:textStyle="bold"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true"
    android:gravity="center_vertical"
    android:layout_width="match_parent"
    android:background="#e7e7e1"
    xmlns:android="http://schemas.android.com/apk/res/android" />

<TextView
    android:id="@+id/text_view_name"
    android:visibility="visible"
    android:layout_height="30dp"
    android:textColor="@android:color/holo_blue_dark"
    android:paddingLeft="15dp"
    android:textStyle="bold"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true"
    android:gravity="center_vertical"
    android:layout_width="match_parent"
    android:background="#e7e7e1"
    xmlns:android="http://schemas.android.com/apk/res/android" />

• TextView textView = (TextView) findViewById(R.id.text_view_name);
                  textView.setVisibility(View.VISIBLE);

• TextView textView = (TextView) findViewById(R.id.text_view_name);
                  textView.setVisibility(View.INVISIBLE);

• TextView textView = (TextView) findViewById(R.id.text_view_name);
                  textView.setVisibility(View.GONE);

Points To Remember

How to change the Android Application Icon 

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ekiras.activity" >

    <application
        android:allowBackup="true"
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        // Your activities are declared here
        <activity></activity>
    </application>

</manifest>

<resources>
    <string name="app_name">Ekiras</string>
    <string name="action_settings">Settings</string>
</resources>

Points To Remember

• You need to create a ListView in your activity.
• Then create a view for Item of the ListView.
• Create an Adapter and a list of objects to display.
• Pass the List of objects to the ListView.

How to create a Basic List View 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="Planet List"
        android:textAlignment="center"
        android:textSize="24dp"
        />
    <ListView
        android:id="@+id/list_view_drawer"
        android:layout_marginTop="50dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:dividerHeight="1dp"
        android:divider="@android:color/holo_blue_light"
        xmlns:android="http://schemas.android.com/apk/res/android" />


</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<TextView
    android:layout_height="50dp"
    android:textAlignment="gravity"
    android:textColor="@android:color/holo_blue_dark"
    android:paddingLeft="15dp"
    android:layout_centerVertical="true"
    android:layout_centerHorizontal="true"
    android:gravity="center_vertical"
    android:layout_width="wrap_content"
    xmlns:android="http://schemas.android.com/apk/res/android" />

package com.ekiras.demo;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

import com.ekiras.app2.fragment.BuzzListFragment;

public class MainActivity extends ActionBarActivity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        String [] planets = new String[]{
          "Mercury","Mars","Earth","Jupitor","Mars","Venus","Pluto"
        };

        ArrayAdapter adapter = new ArrayAdapter<String>(this, R.layout.list_view_item, planets);

        ListView listView = (ListView) findViewById(R.id.list_view_drawer);
        listView.setAdapter(adapter);
    }

}

Your Application will look as shown in the image

Points To Remember

How to change ActionBar/ ToolBar color

• We will create a new file colors.xmlif it does not exist.
• Override the Primary color of the theme Theme.AppCompat.Light.DarkActionBar
• See the results

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="primary_material_dark">#1B5891</color>
</resources>

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
    </style>

</resources>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ekiras.demo" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Points To Remember

• You need to create a file in res > menu > menu.xml
• You can use showAsAction property to decide if to show the action icon on action bar or not. 

Adding Action Icon Action button on Action Bar

• app:showAsAction="never"

  This will show the action in the list view when menu icon is pressed.

• app:showAsAction="ifRoom"

  This will show the action in the action bar if the amount of space required to show the action is available on the Action bar.

<menu 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"
    tools:context=".HomeActivity">

    <item
        android:id="@+id/action_settings"
        android:orderInCategory="100"
        android:title="#Settings"
        app:showAsAction="never" />

    <item
        android:id="@+id/app_search"
        android:orderInCategory="99"
        android:title="#Search"
        app:showAsAction="ifRoom" />

</menu>

Line 7 and 13 tells how to order them in the list.
Line 10 and 16 tells how to show the action in the action bar.

Output will look the following

Points To Remember

How to change application icon

1. Add the icon.png folder in the drawable folder
2. Open the Application > manifests > AndroidManifests.xml file
3. Add

   android:icon="@drawable/icon"

   in the application root.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ekiras.activity" >
 
    <application
        android:allowBackup="true"
        android:icon="@drawable/icon"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        // Your activities are declared here
        <activity></activity>
    </application>
 
</manifest>