Hi!
I know two ways to save/load application settings:
use PersistentStore
use filesystem (store, since SDCard is optional)
I'd like to know what are you're practicies of working with application settings?
Using PersistentStore to save/load application settings
The persistent store provides a means for objects to persist across device resets. A persistent object consists of a key-value pair. When a persistent object is committed to the persistent store, that object's value is stored in flash memory via a deep copy. The value can then be retrieved at a later point in time via the key.
Example of helper class for storing and retrieving settings:
class PSOptions {
private PersistentObject mStore;
private LongHashtableCollection mSettings;
private long KEY_URL = 0;
private long KEY_ENCRYPT = 1;
private long KEY_REFRESH_PERIOD = 2;
public PSOptions() {
// "AppSettings" = 0x71f1f00b95850cfeL
mStore = PersistentStore.getPersistentObject(0x71f1f00b95850cfeL);
}
public String getUrl() {
Object result = get(KEY_URL);
return (null != result) ? (String) result : null;
}
public void setUrl(String url) {
set(KEY_URL, url);
}
public boolean getEncrypt() {
Object result = get(KEY_ENCRYPT);
return (null != result) ? ((Boolean) result).booleanValue() : false;
}
public void setEncrypt(boolean encrypt) {
set(KEY_ENCRYPT, new Boolean(encrypt));
}
public int getRefreshPeriod() {
Object result = get(KEY_REFRESH_PERIOD);
return (null != result) ? ((Integer) result).intValue() : -1;
}
public void setRefreshRate(int refreshRate) {
set(KEY_REFRESH_PERIOD, new Integer(refreshRate));
}
private void set(long key, Object value) {
synchronized (mStore) {
mSettings = (LongHashtableCollection) mStore.getContents();
if (null == mSettings) {
mSettings = new LongHashtableCollection();
}
mSettings.put(key, value);
mStore.setContents(mSettings);
mStore.commit();
}
}
private Object get(long key) {
synchronized (mStore) {
mSettings = (LongHashtableCollection) mStore.getContents();
if (null != mSettings && mSettings.size() != 0) {
return mSettings.get(key);
} else {
return null;
}
}
}
}
Example of use:
class Scr extends MainScreen implements FieldChangeListener {
PSOptions mOptions = new PSOptions();
BasicEditField mUrl = new BasicEditField("Url:",
"http://stackoverflow.com/");
CheckboxField mEncrypt = new CheckboxField("Enable encrypt", false);
GaugeField mRefresh = new GaugeField("Refresh period", 1, 60 * 10, 10,
GaugeField.EDITABLE|FOCUSABLE);
ButtonField mLoad = new ButtonField("Load settings",
ButtonField.CONSUME_CLICK);
ButtonField mSave = new ButtonField("Save settings",
ButtonField.CONSUME_CLICK);
public Scr() {
add(mUrl);
mUrl.setChangeListener(this);
add(mEncrypt);
mEncrypt.setChangeListener(this);
add(mRefresh);
mRefresh.setChangeListener(this);
HorizontalFieldManager hfm = new HorizontalFieldManager(USE_ALL_WIDTH);
add(hfm);
hfm.add(mLoad);
mLoad.setChangeListener(this);
hfm.add(mSave);
mSave.setChangeListener(this);
loadSettings();
}
public void fieldChanged(Field field, int context) {
if (field == mLoad) {
loadSettings();
} else if (field == mSave) {
saveSettings();
}
}
private void saveSettings() {
mOptions.setUrl(mUrl.getText());
mOptions.setEncrypt(mEncrypt.getChecked());
mOptions.setRefreshRate(mRefresh.getValue());
}
private void loadSettings() {
mUrl.setText(mOptions.getUrl());
mEncrypt.setChecked(mOptions.getEncrypt());
mRefresh.setValue(mOptions.getRefreshPeriod());
}
}
