Android Tutorials for Beginners

Wednesday, September 4, 2013

PreferenceActivity In Android Example

PreferenceActivity is the base class for an activity to show a hierarchy of preferences to the user.
It is generally used for saving the setting/preference of User. Android provides excellent framework to save and mange the User preferences.
We just need to use the class and specify some resources , and it automatically creates GUI for that itself.

PreferenceActivity Example In Android:

In this example I have created a Page/Screen with user can save his password, and other choices/details.

Steps:

1: Create xml resource for Preference: create an xml file inside xml folder (if xml folder is not there inside res folder, create xml folder inside res folder. In the example I have created user_settings.xml file inside xml folder.

2: Create a Class which extends PreferenceActivity class , and inflate the created xml using addPreferencesFromResource() method.

3: Call/Start the PreferenceActivity (created in 2nd steps) from where you want. In the example I have called from MainActivity using startActivityForResult() method.

Now lets go Step by Step:

Step1: Create XML resource inside xml folder:

user_settings.xml

This file defines user interface for setting page. We have created 3 different categories here.

1: EditTextPreference is used to define an editable text property. In this example used this field to enter the Password
2:CheckBoxPreference allows you to define a boolean value in preference screen.
3: ListPreference   display choices from which user can select one.. In this examplewe have used ListPreference to choose the frequency when user should be reminded.

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

    <PreferenceCategory android:title="Settings" >
        <EditTextPreference
                android:title="Password"
                android:summary="Set Your Password"
                android:key="prefUserPassword"/>
    </PreferenceCategory>

    <PreferenceCategory android:title="Security Settings" >
        <CheckBoxPreference
            android:defaultValue="false"
            android:key="prefLockScreen"
            android:summary="Lock The Screen With Password"
            android:title="Screen Lock" >
        </CheckBoxPreference>

        <ListPreference
            android:key="prefUpdateFrequency"
            android:title="Reminder for Updation"
            android:summary="Set Update Reminder Frequency"
            android:entries="@array/updateFrequency"
            android:entryValues="@array/updateFrequencyValues"
            />
    </PreferenceCategory>

</PreferenceScreen>

Since we have used arrays here, We need to define it inside array.xml file.
Create an arrays.xml file inside values folder and write following

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="updateFrequency">
        <item name="1">Daily</item>
        <item name="7">Weekly</item>
        <item name="3">Yearly</item>
        <item name="0">Never(I will Myself) </item>
    </string-array>
    <string-array name="updateFrequencyValues">
        <item name="1">1</item>
        <item name="7">7</item>
        <item name="30">30</item>
        <item name="0">0</item>
    </string-array>

</resources>

2: Create a Class which extends PreferenceActivity class

public class UserSettingActivity extends PreferenceActivity
{

             @Override
             public void onCreate(Bundle savedInstanceState)
             {
                     super.onCreate(savedInstanceState);
                      // add the xml resource                     addPreferencesFromResource(R.xml.user_settings);


             }

}

3: Call/Start the PreferenceActivity.

We have called UserSettingActivity from MainActivity

xml for MainActivity

main.xml   contains two things

1: Button: We start UserSettingActivity when user clicks on this buttons.
2: TextView:   To show the User data like password etc.

<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"
    android:background="#CCCCFF"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/buttonSettings"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="150dp"
        android:textSize="25dp"
        android:text="Settings" />

    <TextView
        android:id="@+id/textViewSettings"
        android:textSize="21dp"
        android:textColor="#0000FF"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/buttonSettings"
        android:layout_marginTop="66dp"
        android:text="No Settings"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

MainActivty

public class MainActivity extends Activity
{
            private static final int SETTINGS_RESULT = 1;
            Button settingButton;

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

                        Button btnSettings=(Button)findViewById(R.id.buttonSettings);
                        // start the UserSettingActivity when user clicks on Button
                        btnSettings.setOnClickListener(new View.OnClickListener() {

                            public void onClick(View v) {
                                // TODO Auto-generated method stub
                                Intent i = new Intent(getApplicationContext(), UserSettingActivity.class);
                                startActivityForResult(i, SETTINGS_RESULT);
                            }
                        });
            }

                @Override
                protected void onActivityResult(int requestCode, int resultCode, Intent data)
                {
                            super.onActivityResult(requestCode, resultCode, data);

                                if(requestCode==SETTINGS_RESULT)
                                {
                                    displayUserSettings();
                                }

                }


                private void displayUserSettings()
                {
                        SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);

                        String settings = "";

                        settings=settings+"Password: " + sharedPrefs.getString("prefUserPassword", "NOPASSWORD");

                        settings=settings+"\nRemind For Update:"+ sharedPrefs.getBoolean("prefLockScreen", false);

                        settings=settings+"\nUpdate Frequency: "
                                + sharedPrefs.getString("prefUpdateFrequency", "NOUPDATE");

                        TextView textViewSetting = (TextView) findViewById(R.id.textViewSettings);

                        textViewSetting.setText(settings);
                 }

}

How to fetch the User Saved data:

sharedPrefs.getString("prefUserPassword", "NOPASSWORD");
we need to provide the key , that was given in xml ( android:key="prefUserPassword" in user_settings.xml file )
We need to pass key as first argument and default value as second argumment.

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Saturday, August 24, 2013

Android RatingBar Example

A Rating Bar is used to show rating in Stars.The user can touch/drag or use arrow keys to set the rating when using the default size RatingBar.

RatingBar Example.

main.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:background="#C2C2A3">

<RatingBar

android:id="@+id/ratingBar1"

android:layout_marginTop="50dp"

android:layout_gravity="center_horizontal"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

<Button

android:id="@+id/button1"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_marginTop="50dp"

android:text="OK" />

</LinearLayout>

How to change the Number of Stars

Use android:numStars attribute to set the number of stars you want.

MainActivity.java

public class MainActivity extends Activity

{

RatingBar ratingBar;

Button btn;

@Override

public void onCreate(Bundle savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

ratingBar=(RatingBar)findViewById(R.id.ratingBar1);

btn=(Button)findViewById(R.id.button1);

// Set ChangeListener to Rating Bar

ratingBar.setOnRatingBarChangeListener(new OnRatingBarChangeListener() {

public void onRatingChanged(RatingBar ratingBar, float rating,

boolean fromUser) {

Toast.makeText(getApplicationContext(),"Your Selected Ratings : " + String.valueOf(rating),Toast.LENGTH_LONG).show();

}

});

btn.setOnClickListener(new View.OnClickListener() {

public void onClick(View arg0) {

// TODO Auto-generated method stub

float rating=ratingBar.getRating();

Toast.makeText(getApplicationContext(),"Your Selected Ratings : " + String.valueOf(rating),Toast.LENGTH_LONG).show();

}

});

}

How to Set The Rating at Run time
use method

ratingBar.setRating(4); or pass any number like 3.5, 4.5 etc.

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Android Custom Adapter Example

The Android Development Tutorials blog contains Basic as well as Advanced android tutorials.Go to Android Development Tutorials to get list of all Android Topics.

Populate ListView with Custom Adapter

ListView can be populated by ArrayAdapter, Database, ArrayList etc
In this post I will describe how to populate ListView using a Custom Adapter.

Have a look at my previous post
Populating ListView with Database
Populating ListView with ArrayList

ListView with Custom Adapter Example

In this example I have created a listView and populated it with Custom Adapter.
Each of the ListView item contain two views
TextView SMS Sender : to show SMS Sender Number
TextView SMSBody : to show the SMS Body/content

Here the ListView shows the all the SMSes with Sender Number and SMSBody.

What we need to do ..
Create a Custom Adapter
and add/set the adapter to ListView.

Add the following permission in your manifest file to read the SMS..
<uses-permission android:name="android.permission.READ_SMS"/>
<uses-permission android:name="android.permission.WRITE_SMS"/>

listview_activity_main.xml

listview_each_item.xml

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

    <TextView
        android:id="@+id/textViewSMSSender"
        android:paddingLeft="2dp"
        android:textSize="20dp"
        android:textStyle="bold"
        android:textColor="#0000FF"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView" />

    <TextView
        android:id="@+id/textViewMessageBody"
        android:paddingLeft="5dp"
        android:textColor="#5C002E"
        android:textSize="17dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView" />

</LinearLayout>

</LinearLayout>

ListViewMainActivity.java

public class ListViewMainActivity extends Activity
{
            ListView listViewSMS;
            Cursor cursor;
            SMSListAdapter smsListAdapter;
            Context context;
            @Override
            protected void onCreate(Bundle savedInstanceState)
            {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.listview_activity_main);

                    context=this;
                    listViewSMS=(ListView)findViewById(R.id.listViewSMS);

                    cursor = getContentResolver().query(Uri.parse("content://sms/inbox"), null, null, null, null);

                    // Create the Adapter
                    smsListAdapter=new SMSListAdapter(this,cursor);

                    // Set The Adapter to ListView
                    listViewSMS.setAdapter(smsListAdapter);

                    // to handle click event on listView item
                    listViewSMS.setOnItemClickListener(new OnItemClickListener()
                    {
                            public void onItemClick(AdapterView<?> arg0, View v,int position, long arg3)
                            {
                                // when user clicks on ListView Item , onItemClick is called
                                // with position and View of the item which is clicked
                                // we can use the position parameter to get index of clicked item
                                TextView textViewSMSSender=(TextView)v.findViewById(R.id.textViewSMSSender);
                                TextView textViewSMSBody=(TextView)v.findViewById(R.id.textViewMessageBody);
                                String smsSender=textViewSMSSender.getText().toString();
                                String smsBody=textViewSMSBody.getText().toString();

                                // Show The Dialog with Selected SMS
                                AlertDialog dialog = new AlertDialog.Builder(context).create();
                                dialog.setTitle("SMS From : "+smsSender);
                                dialog.setIcon(android.R.drawable.ic_dialog_info);
                                dialog.setMessage(smsBody);
                                dialog.setButton(DialogInterface.BUTTON_POSITIVE, "OK",
                                        new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int which)
                                    {

                                            dialog.dismiss();
                                            return;
                                }
                                });
                                dialog.show();
                            }
                        });

            }
}

SMSListAdapter.java : The Custom Adapter

public class SMSListAdapter extends BaseAdapter
{

    private Context mContext;
    Cursor cursor;
    public SMSListAdapter(Context context,Cursor cur)
    {
            super();
            mContext=context;
            cursor=cur;

    }

    public int getCount()
    {
        // return the number of records in cursor
        return cursor.getCount();
    }

    // getView method is called for each item of ListView
    public View getView(int position, View view, ViewGroup parent)
    {
                    // inflate the layout for each item of listView
                    LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                    view = inflater.inflate(R.layout.listview_each_item, null);

                    // move the cursor to required position
                    cursor.moveToPosition(position);

                    // fetch the sender number and sms body from cursor
                    String senderNumber=cursor.getString(cursor.getColumnIndex("address"));
                    String smsBody=cursor.getString(cursor.getColumnIndex("body"));

                    // get the reference of textViews
                    TextView textViewConatctNumber=(TextView)view.findViewById(R.id.textViewSMSSender);
                    TextView textViewSMSBody=(TextView)view.findViewById(R.id.textViewMessageBody);

                    // Set the Sender number and smsBody to respective TextViews
                    textViewConatctNumber.setText(senderNumber);
                    textViewSMSBody.setText(smsBody);


                    return view;
    }

    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }
}