AutoCompleteOnPreferences.java

package com.osmnavigator;

import java.util.LinkedList;
import org.json.JSONArray;
import org.json.JSONException;
import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;

/**
 * AutoCompleteTextView taking its list of values from a shared preference. 
 * 
 * Use the static method storePreference(value) to add an entry in these preferences
 * (typically when the user "uses" a value he just entered in this edittext view). 
 * 
 * @author M.Kergall
 */
public class AutoCompleteOnPreferences extends AutoCompleteTextView {

	public AutoCompleteOnPreferences(Context context) {
		super(context);
	}
	
	public AutoCompleteOnPreferences(Context arg0, AttributeSet arg1) {
		super(arg0, arg1);
	}
	
	public AutoCompleteOnPreferences(Context arg0, AttributeSet arg1, int arg2) {
		super(arg0, arg1, arg2);
	}

	@Override public boolean enoughToFilter() {
		return true;
	}
	
	@Override protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
		super.onFocusChanged(focused, direction, previouslyFocusedRect);
		if (focused){
			setPreferences();
			if (getAdapter()!=null) {
				performFiltering(getText(), 0);
			}
		}
	}
	
	protected String mAppKey, mKey;
	
	/**
	 * Specify which application key and which preference name will be used. 
	 * @param appKey Shared Preferences application key
	 * @param prefName Preference name
	 */
	public void setPrefKeys(String appKey, String prefName){
		mAppKey = appKey;
		mKey = prefName;
	}
	
	protected void setPreferences(){
		String[] prefs = getPreferences();
		ArrayAdapter<String> adapter = new ArrayAdapter<String>(getContext(),
				android.R.layout.simple_dropdown_item_1line, prefs);
		this.setAdapter(adapter);
	}

	protected String[] getPreferences(){
		SharedPreferences prefs = getContext().getSharedPreferences(mAppKey, Context.MODE_PRIVATE);
		String prefString = prefs.getString(mKey, "[]");
		try {
			JSONArray prefArray = new JSONArray(prefString);
			String[] result = new String[prefArray.length()];
			for (int i=0; i<prefArray.length(); i++){
				result[i] = prefArray.getString(i);
			}
			return result;
		} catch (JSONException e) {
			e.printStackTrace();
			return new String[0];
		}
	}
	
	/**
	 * Add a value in a list of preferences referenced by an appKey and a prefName. 
	 * @param context
	 * @param value to add in the list. 
	 * @param appKey application key
	 * @param prefName name of the preferences list
	 */
	public static void storePreference(Context context, String value, String appKey, String prefName){
		SharedPreferences prefs = context.getSharedPreferences(appKey, Context.MODE_PRIVATE);
		String prefValues = prefs.getString(prefName, "[]");
		JSONArray prefValuesArray;
		try {
			prefValuesArray = new JSONArray(prefValues);
			LinkedList<String> prefValuesList = new LinkedList<String>();

			for (int i=0; i<prefValuesArray.length(); i++){
				String prefValue = prefValuesArray.getString(i);
				if (!prefValue.equals(value))
					prefValuesList.addLast(prefValue);
				//else, don't add it => it will be added at the beginning, as a new one...
			}
			//add the new one at the beginning:
			prefValuesList.addFirst(value);
			//remove last entry if too much:
			if (prefValuesList.size()>20)
				prefValuesList.removeLast();

			//Rebuild JSON string:
			prefValuesArray = new JSONArray();
			for (String s:prefValuesList){
				prefValuesArray.put(s);
			}
			prefValues = prefValuesArray.toString();
			SharedPreferences.Editor ed = prefs.edit();
			ed.putString(prefName, prefValues);
			ed.commit();
		} catch (JSONException e) {
			e.printStackTrace();
		}
	}
}