Question

I'm making an app where whenever you go to an activity, it plays a sound file. I made a preference in which you can change the sound file it plays. Here's the code for the Preference activity:

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

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

    <ListPreference     android:title="Sound"
        android:summary="Pick the sound!"
        android:key="soundChoice"
        android:defaultValue="a"
        android:entries="@array/soundList"
        android:entryValues="@array/soundValues" />

</PreferenceScreen>

and here is the array file stuff:

<string-array name="soundList">
    <item>Sound 1</item>
    <item>Sound 2</item>
    <item>Sound 3</item>
    <item>Sound 4</item>
</string-array>
<string-array name="soundValues">
    <item>a</item>
    <item>b</item>
    <item>c</item>
    <item>d</item>
</string-array>

and here is the onCreate for the Activity that plays the sound file:

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    SharedPreferences SP = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
    //Have also tried using "this" instead of "getBaseContext(). Same result.
    String choiceSound = SP.getString("soundChoice","a");

    // TODO

    if(choiceSound == "a"){

        mediaPlayer = MediaPlayer.create(this, R.raw.sound1); 
        mediaPlayer.start();

    }
    else if(choiceSound == "b") {

        mediaPlayer = MediaPlayer.create(this, R.raw.sound2); 
        mediaPlayer.start();

    }
    setContentView(R.layout.activity_sounder);
}

My problem is, the SharedPreferences is not getting the value from whatever the user selected.
So the mediaplayer is never being created, causing the app to crash whenever I exit the activity because I release the MediaPlayer in the onStop() method.
Is my constructor for the SharedPreference/PreferenceManager correct?
Any ideas on what I am doing wrong or how I could fix it?

Answer 1

Try checking your strings with equals() instead of ==.

if(choiceSound.equals("a"))

instead of

if(choiceSound == "a")

'==' compares for the reference of the object. you want to check for the value of it.

Preference Manager not getting value from user preferences

1 个答案: