Example of extending EditTextPreference to create a preference that saves numbers (EditTextPreference saves strings even if you specify "android:inputType=number ")

NumericPreference

/*
 * NumericPreference.java
 * 
 *Copyright © Ropardo™ 2013.
 */
package ro.ropardo.imobiledistribution.utils;

import android.content.Context;
import android.preference.EditTextPreference;
import android.util.AttributeSet;
import android.util.Log;

/**
 * @author Stelian Morariu
 * 
 */
public class NumericPreference extends EditTextPreference {

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

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

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

	@Override
	protected String getPersistedString(String defaultReturnValue) {
		long aux = -1l;

		if (defaultReturnValue != null && defaultReturnValue.length() > 0) {
			try {
				aux = Long.valueOf(defaultReturnValue);
			} catch (Exception e) {
				Log.e(NumericPreference.class.getSimpleName(), "Invalid default value for Long : " + e.toString());
			}
		}
		return String.valueOf(getPersistedLong(aux));
	}

	@Override
	protected boolean persistString(String value) {
		return persistLong(Long.valueOf(value));
	}
}