Android Development 21
In this part of my Android Development Tutorial, I cover numerous topics. This tutorial started in part 18 of this series and you should start watching there to understand everything.
I cover the following : FragmentManager, Creating list items for a ListView, ListFragment, Android Adapters, ArrayAdapter, Generating items from an ArrayList for a ListView and more. All of the code follows the video, but it is also available as a complete package here.
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Code From the Video
list_item_contact.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/RelativeLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<CheckBox android:id="@+id/contact_contacted_checkbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_alignParentRight="true"
android:padding="4dp" />
<TextView
android:id="@+id/contact_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_toLeftOf="@id/contact_contacted_checkbox"
android:padding="4dp"
android:text="@string/list_item_contact_name"
android:textStyle="bold" />
<TextView
android:id="@+id/contact_street"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/contact_name"
android:layout_toLeftOf="@id/contact_contacted_checkbox"
android:padding="4dp"
android:text="@string/list_item_contact_street" />
</RelativeLayout>
ContactListActivity.java
package com.newthinktank.censusapp;
//We will use the android.support.v4.app.Fragment
//support library so our app runs on older versions
//of Android
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
//Change Activity to FragmentActivity
// The FragmentManager ads Fragments to an Activity's view
public class ContactListActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_census_app);
FragmentManager fragManager = getSupportFragmentManager();
// Check if the FragmentManager knows about the Fragment
// id we refer to
Fragment theFragment = fragManager.findFragmentById(R.id.fragmentContainer);
// Check if the Fragment was found
if(theFragment == null){
// If the Fragment wasn't found then we must create it
// We change this from ContactFragment, which we used
// in CensusApp
theFragment = new FragmentContactList();
// Creates and commits the Fragment transaction
// Fragment transactions add, attach, detach, replace
// and remove Fragments.
// add() gets the location to place the Fragment into and
// the Fragment itself.
fragManager.beginTransaction()
.add(R.id.fragmentContainer, theFragment)
.commit();
}
}
}
FragmentContactList.java
package com.newthinktank.censusapp;
import java.util.ArrayList;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.TextView;
// The ListFragment displays a list of items in a
// ListView, by binding to our ArrayList using an
// ArrayAdapter in this situation.
public class FragmentContactList extends ListFragment {
// Stores the list of Contacts
private ArrayList<Contact> contactList;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Change the title for the current Activity
getActivity().setTitle(R.string.fragment_contact_list_title);
// Get the ArrayList from AllContacts
contactList = AllContacts.get(getActivity()).getContactList();
ContactAdapter contactAdapter = new ContactAdapter(contactList);
// Provides the data for the ListView by setting the Adapter
setListAdapter(contactAdapter);
}
private class ContactAdapter extends ArrayAdapter<Contact> {
public ContactAdapter(ArrayList<Contact> contacts) {
// An Adapter acts as a bridge between an AdapterView and the
// data for that view. The Adapter also makes a View for each
// item in the data set. (Each list item in our ListView)
// The constructor gets a Context so it so it can use the
// resource being the simple_list_item and the ArrayList
// android.R.layout.simple_list_item_1 is a predefined
// layout provided by Android that stands in as a default
super(getActivity(), android.R.layout.simple_list_item_1, contacts);
}
// getView is called each time it needs to display a new list item
// on the screen because of scrolling for example.
// The Adapter is asked for the new list row and getView provides
// it.
// position represents the position in the Array from which we will
// be pulling data.
// convertView is a pre-created list item that will be reconfigured
// in the code that follows.
// ViewGroup is our ListView
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// Check if this is a recycled list item and if not we inflate it
if(convertView == null){
convertView = getActivity().getLayoutInflater()
.inflate(R.layout.list_item_contact, null);
}
// Find the right data to put in the list item
Contact theContact = getItem(position);
// Put the right data into the right components
TextView contactNameTextView =
(TextView)convertView.findViewById(R.id.contact_name);
contactNameTextView.setText(theContact.getName());
TextView streetTextView =
(TextView)convertView.findViewById(R.id.contact_street);
streetTextView.setText(theContact.getStreetAddress());
CheckBox contactedCheckBox =
(CheckBox)convertView.findViewById(R.id.contact_contacted_checkbox);
contactedCheckBox.setChecked(theContact.getContacted());
// Return the finished list item for display
return convertView;
}
}
}
activity_census_app.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/fragmentContainer"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- This will be the container for our fragments -->
</FrameLayout>
strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Census App</string>
<string name="action_settings">Settings</string>
<string name="contact_name_hint">Enter Name</string>
<string name="contact_phone_hint">Enter Phone Number</string>
<string name="contact_street_hint">Enter Street</string>
<string name="contact_city_hint">Enter City</string>
<!-- NEW -->
<string name="contact_contacted_checkbox">Contacted</string>
<string name="fragment_contact_list_title">Contacts</string>
<string name="list_item_contact_name">Name</string>
<string name="list_item_contact_street">Street</string>
</resources>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.newthinktank.censusapp"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<!-- NEW -->
<activity
android:name="com.newthinktank.censusapp.ContactListActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<!-- END OF NEW -->
<activity
android:name="com.newthinktank.censusapp.CensusApp"
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>
Tnx a Bunch,
Looking forward to the final app 🙂
There are many many more apps coming 🙂
Could u please tell in advance which topics u will be covering in the following tutorials? Would be nice if u could do that…
Really great job though ….. your tutorials are my main source of learning apart from the android developers site itself
Thanking you
Thank you 🙂 I’ll see if I can narrow them down in the next video. Thank you for the input.
And is there any way u could do a few tutorials on sync adapters and GCM and multi-threading later on …. would be great
Yes I will cover those topics ASAP
Hey, Derek! Nice tutorial.. but I seem to have trouble with the app.. It loads the ContactListActivity but it only shows one contact with the name and 2 more rows without a name or street.. but it does have a checkbox.. what could be the problem? 😕
Hey, Did you try importing and running the complete package I have here. If that doesn’t run I’ll take a further look. If it does, check your code using diffnow.com.