PreferenceActivity: save value as integer

Question

Using a simple EditTextPreference in my preferences activity:

<EditTextPreference
    android:key="SomeKey"
    android:title="@string/some_title"
    android:summary="..."
    android:numeric="integer"
    android:maxLength="2"
/>

Is there a way that this configuration value would be saved as integer? Seems now it just allows to enter numbers, but the value is still saved as string:

Calling:

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
int value = preferences.getInt("SomeKey", -1);

throws me java.lang.ClassCastException: java.lang.String, and:

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
String value = preferences.getString("SomeKey", "-1");

retrieves the value successfully.

How to make PreferenceActivity to save value as integer by default?

Answer 1

You could extend EditTextPreference:

public class IntEditTextPreference extends EditTextPreference {

    public IntEditTextPreference(Context context) {
        super(context);
    }

    public IntEditTextPreference(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public IntEditTextPreference(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected String getPersistedString(String defaultReturnValue) {
        return String.valueOf(getPersistedInt(-1));
    }

    @Override
    protected boolean persistString(String value) {
        return persistInt(Integer.valueOf(value));
    }
}

It would be better to overwrite onSetInitialValue() and setText() methods, but then you would have to copy some code from a base class. Above solution is simplier, but it's quite tricky - "string" methods do something with ints. Try to not extend this class further ;-)

You could use it from XML by:

<package.name.IntEditTextPreference
    android:key="SomeKey"
    android:title="@string/some_title"
    android:summary="..."
    android:numeric="integer"
    android:maxLength="2"
/>