Chủ Nhật, 8 tháng 7, 2012

Example of using PreferenceFragment

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11:58
In my old post "Preferences and SharedPreferences" describe how to implement PreferenceActivity calling deprecated addPreferencesFromResource() method. PreferenceActivity is the base class for an activity to show a hierarchy of preferences to the user. Prior to HONEYCOMB this class only allowed the display of a single set of preference; this functionality should now be found in the new PreferenceFragment class.

It's a example of using PreferenceFragment.

Example of PreferenceFragment


New a Android Application Project, AndroidPreferenceFragment, with Build SDK target Android 4.1 (API 16) and Minimum Required Android 3.0 (API 11), BlankActivity with Navigation Type of None.

Create /res/xml/preferences.xml to define our preferences.
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android">

<PreferenceCategory
android:title="PreferenceCategory A">

<CheckBoxPreference
android:key="checkbox_preference"
android:title="title_checkbox_preference"
android:summary="summary_checkbox_preference" />

</PreferenceCategory>

<PreferenceCategory
android:title="PreferenceCategory B">

<EditTextPreference
android:key="edittext_preference"
android:title="title_edittext_preference"
android:summary="summary_edittext_preference"
android:dialogTitle="dialog_title_edittext_preference" />

</PreferenceCategory>

</PreferenceScreen>


Create PrefsFragment.java extends PreferenceFragment to addPreferencesFromResource.
package com.example.androidpreferencefragment;

import android.os.Bundle;
import android.preference.PreferenceFragment;

public class PrefsFragment extends PreferenceFragment {

@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);

// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences);
}

}


Create SetPreferenceActivity.java to load PrefsFragment.
package com.example.androidpreferencefragment;

import android.app.Activity;
import android.os.Bundle;

public class SetPreferenceActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);

getFragmentManager().beginTransaction().replace(android.R.id.content,
new PrefsFragment()).commit();
}

}


Modify the main layout, /res/layout/activity_main.xml, to show the preference.
<LinearLayout 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:orientation="vertical" >

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="@dimen/padding_medium"
android:text="@string/hello_world"
tools:context=".MainActivity" />

<CheckBox
android:id="@+id/prefCheckBox"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="CheckBoxPreference" />

<TextView
android:id="@+id/prefEditText"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />

</LinearLayout>


The main activity, MainActivity.java.
package com.example.androidpreferencefragment;

import android.os.Bundle;
import android.preference.PreferenceManager;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.CheckBox;
import android.widget.TextView;

public class MainActivity extends Activity {

CheckBox prefCheckBox;
TextView prefEditText;

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

prefCheckBox = (CheckBox)findViewById(R.id.prefCheckBox);
prefEditText = (TextView)findViewById(R.id.prefEditText);

loadPref();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

/*
* Because it's onlt ONE option in the menu.
* In order to make it simple, We always start SetPreferenceActivity
* without checking.
*/

Intent intent = new Intent();
intent.setClass(MainActivity.this, SetPreferenceActivity.class);
startActivityForResult(intent, 0);

return true;
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
//super.onActivityResult(requestCode, resultCode, data);

/*
* To make it simple, always re-load Preference setting.
*/

loadPref();
}

private void loadPref(){
SharedPreferences mySharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

boolean my_checkbox_preference = mySharedPreferences.getBoolean("checkbox_preference", false);
prefCheckBox.setChecked(my_checkbox_preference);

String my_edittext_preference = mySharedPreferences.getString("edittext_preference", "");
prefEditText.setText(my_edittext_preference);

}

}


Finally, modify AndroidManifest.xml to add SetPreferenceActivity.
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.androidpreferencefragment"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="15" />

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

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".SetPreferenceActivity"
android:label="@string/title_activity_main" >
</activity>
</application>

</manifest>


Download the files.

Next:
- PreferenceFragment with ListPreference


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