Programming Tutorials

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Android Preferences - Using Preferences in Android Tutorial

By: Ashley in Android Tutorials on 2011年10月02日 [フレーム]

This sample android program shows you how to use preferences in Android. In this program the concept of storing the user's preferences in a SharedPreferences object is demonstrated. With this sharedpreference you can store and retrieve preferences and use it in any of your activities.

The PreferenceDemo1.java file is as follows:

package com.javasamples.PreferenceDemo1;
import java.util.Date;
import android.app.Activity;
import android.content.SharedPreferences;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class PreferenceDemo1 extends Activity implements OnClickListener {
	Button btnSimplePref;
	Button btnFancyPref;
	TextView txtCaption1;
	Boolean fancyPrefChosen = false;
	View myLayout1Vertical;
	
	final int mode = Activity.MODE_PRIVATE;
	final String MYPREFS = "MyPreferences_001";
	// create a reference to the shared preferences object
	SharedPreferences mySharedPreferences;
	// obtain an editor to add data to my SharedPreferences object
	SharedPreferences.Editor myEditor;
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		
		myLayout1Vertical = (View)findViewById(R.id.linLayout1Vertical);
		
		txtCaption1 = (TextView) findViewById(R.id.txtCaption1);
		txtCaption1.setText("This is a sample line \n"
				+ "suggesting the way the UI looks \n"
				+ "after you choose your preference");
		// create a reference to the shared preferences object
		mySharedPreferences = getSharedPreferences(MYPREFS, 0);
		// obtain an editor to add data to (my)SharedPreferences object
		myEditor = mySharedPreferences.edit();
		// has a Preferences file been already created?
		if (mySharedPreferences != null
				&& mySharedPreferences.contains("backColor")) {
			// object and key found, show all saved values
			applySavedPreferences();
		} else {
			Toast.makeText(getApplicationContext(), 
					"No Preferences found", 1).show();
		}
		btnSimplePref = (Button) findViewById(R.id.btnPrefSimple);
		btnSimplePref.setOnClickListener(this);
		btnFancyPref = (Button) findViewById(R.id.btnPrefFancy);
		btnFancyPref.setOnClickListener(this);
	}// onCreate
	public void onClick(View v) {
		// clear all previous selections
		myEditor.clear();
		// what button has been clicked?
		if (v.getId() == btnSimplePref.getId()) {
			myEditor.putInt("backColor", Color.BLACK);// black background
			myEditor.putInt("textSize", 12); 		 // humble small font
		} else { // case btnFancyPref
			myEditor.putInt("backColor", Color.BLUE); // fancy blue
			myEditor.putInt("textSize", 20); 		 // fancy big
			myEditor.putString("textStyle", "bold"); // fancy bold
			myEditor.putInt("layoutColor", Color.GREEN);//fancy green 
		}
		myEditor.commit();
		applySavedPreferences();
	}
	@Override
	protected void onPause() {
		// warning: activity is on its last state of visibility!
		// It's on the edge of been killed! Better save all current 
		// state data into Preference object (be quick!)
		myEditor.putString("DateLastExecution", new Date().toLocaleString());
		myEditor.commit();
		super.onPause();
	}
	public void applySavedPreferences() {
		// extract the  pairs, use default param for missing data
		int backColor = mySharedPreferences.getInt("backColor",Color.BLACK);
		int textSize = mySharedPreferences.getInt("textSize", 12);
		String textStyle = mySharedPreferences.getString("textStyle", "normal");
		int layoutColor = mySharedPreferences.getInt("layoutColor", Color.DKGRAY);
		String msg = "color " + backColor + "\n" + "size " + textSize
				+ "\n" + "style " + textStyle;
		Toast.makeText(getApplicationContext(), msg, 1).show();
		
		txtCaption1.setBackgroundColor(backColor);
		txtCaption1.setTextSize(textSize);
		if (textStyle.compareTo("normal")==0){
			txtCaption1.setTypeface(Typeface.SERIF,Typeface.NORMAL);
		}
		else {
			txtCaption1.setTypeface(Typeface.SERIF,Typeface.BOLD);
		}
		myLayout1Vertical.setBackgroundColor(layoutColor);
	}// applySavedPreferences
}

The Strings.xml file in your res/values/ folder will be as follows

<?xml version="1.0" encoding="utf-8"?>
 
<resources>
 <string name="hello">Hello World, PreferenceDemo0!</string>
 <string name="app_name">PreferencesDemo1</string>
 
</resources>

The main.xml file in your res/layout/ folder will be as follows

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
 android:id="@+id/linLayout1Vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical"
 xmlns:android="http://schemas.android.com/apk/res/android">
 <LinearLayout
 android:id="@+id/linLayout2Horizontal"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content">
 <Button
 android:id="@+id/btnPrefSimple"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="Pref Simple UI">
 </Button>
 <Button
 android:id="@+id/btnPrefFancy"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="Pref Fancy UI">
 </Button>
 </LinearLayout>
 <TextView
 android:id="@+id/txtCaption1"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:background="#ff006666"
 android:text="This is some sample text ">
 </TextView>
 </LinearLayout>

The output of this program will be as shown in the android emulator below.

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