Develop Reference

android - Clearing cache of CheckBoxPreference

I am developing a PreferenceActivity where I can add CheckBoxPreference instances according to some dynamic content. I also maintain a count of the checked preferences in the activity. Everything is good when I load the application for the first time. But when I select some 2-3 check boxes and deploy the application code again on emulator, the previously selected check boxes just remain checked when I come back to same activity. The same happens when I move to and from some activities within the same application!
To prevent this, every time when I create an instance of CheckBoxPreference, I explicitly call .setChecked(false)!!! But still those previously checked preferences remain checked only!
I can't understand the behavior! Does it bring those values checked from cache! But I explicitly call .setChecked(false), what about that then?
Thank you very much,
Ketan
EDIT : Here is my code:
String content = null;
for (String title : titles) {
checkBoxPref = new CheckBoxPreference(this);
checkBoxPref.setKey(title);
checkBoxPref.setTitle(title);
<b>checkBoxPref.setDefaultValue(Boolean.FALSE); //Line # 1 set default to false
checkBoxPref.setChecked(false);//Line # 2 set checked = false </b>
content = config.getString(title, "Yet to define!");
if (content.length() > 30) {
content = content.substring(0, 30);
}
checkBoxPref.setSummary(content);
checkBoxPref.setOnPreferenceChangeListener(new MyCheckBoxChangeListener());
checkBoxPreferenceList.add(checkBoxPref);
inlinePrefCat.addPreference(checkBoxPref);
}
This code is executed everytime I app comes back to this activity! But still had I checked 2-3 checkboxes before leaving this activity, they will remain in the same state when app comes back to this! Please have a look at the code, I am already setting setChecked(false) explicitly, but still can't get them unchecked!
Please suggest some solution! I am stuck!

You will probably have to post some code to get a better answer. I had this same issue when I had my checkbox inside my adapter. I got around the issue by handling the checkbox with an onClickListener:
CheckBox menuOption = (CheckBox) v.findViewById(R.id.list_checkbox);
menuOption.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v)
{
CompoundButton cb = (CompoundButton) v;
// code to set preference goes here
// can check if true or false with cb.isChecked()
}});

Android: setImgVisibility() error

In my app I have a header with icon hidden, I have a adapter with a listview when I click the listview I go to a login screen using listener, when the login is successful is should come back to listview(adapter) and icon should get visible on header.
In the login activity I have the following code:
public void onClick(View v) {
String password = etPassword.getText().toString();
if(password.equals("guest")){
SearchAdapter.setImgVisibility();
} else {
//-----
}
finish();
}
In my adapter I am calling the setImgVisibility() as follows, but it is not working
public static void setImgVisibility() {
img.setVisibility(View.VISIBLE);
}
I am getting a Nullpointerexception near the line img.setVisibility(View.VISIBLE);
I am stuck here and don't know what I am doing wrong. Any suggestions or help is appreciated

I would imagine that img is null. You need to look at where this value is set and make sure happens before you call the method setImgVisibility.
Show more of your complete code for people to help further.
Additionally, i've just noticed you've used a static reference to your search adapter, you should be really careful using statics, especially where any referencing of images is concerned as images can be bound to the context, as such unless you nullify the static you will end up with a memory leak. (this used to be an old problem, not sure its still valid, but i would still avoid using a static reference).
Without more code we're not likely to be able to properly help you. For example are you switching activities when logging in? If you are, this won't work at all.
[given the comment below] If you switch activities then your activity containing the list view is going to be destroyed and then rebuilt then you navigate back to it. or it will at least go through the activity lifecycle. This means you can set the icon during the instantiation of the header img.
You could store your logged in state as a property of the Application or a preference. Grab this value when you set the header image and set the image accordingly.

your img object is null. Is your img object is same as View v then you can pass v in setImgVisibility() and then set v.setVisibility(View.VISIBLE)

StoreData even phone rebooted

My app has this appearance
It seems to be a TableLayout with several TableRows. In my activity, each TableRow has 3 views: ImageView, TextView and a Button.
The user is the one who sets the content of the ImageView and the TestView by entering the text he wants and pressing a button.
I store this data in stringArray variables and works fine if the phone is not restarted or the app is not closed (forceClose)
If one of these two situations happen, i lose all my data.
I've been trying to store my StringArrays by SharedPreferences but I don't know when i should load the preferences, whether it's in OnCreate() or OnResume() or OnStart methods().
Another question is how to define the arrays. I use this:
String[] titulo = new String[500];
I don't know if this string is created each time i start the activity. Because what i want is to load the previous String (from SharedPreferences) and add some more entries not to create new ones every time the phone is rebooted, for example.
Do you think i need a SQL database or it's OK with this StringArrays.
Thank you.

You should probably switch to using a database, seeing as you have an array of size 500, which could possibly increase in the future.
However, if you want to continue using SharedPreferences, you should write the data in onPause() and onStop() methods, and use an if else statement to see if your data is null before running an operation on it. If the data is null, the read it from the SharedPreferences before continuing.

AlertDialog vs Spinner vs ListView

I've got what I thought was a simple android UI design problem but I've been going around in circles for a couple of days. I have a REST service that I'm downloading XML from and displaying the XML in a form in an android app. I have a web page built and am mimicking this with android, same options, same URLs being sent to the REST service whether from android or the web pages. With HTML I can easily create checkbox groups and radiobutton/dropdowns for various id/display items, so for instance, I can display a planet option as:
<select name="planet"><option value="0">Mercury</option></select>
I wanted to do something similar in android where I had a pair of values, one an id and the other the user-friendly text to display. So I decided to create an adapter using android.util.Pair:
public class PairView extends Pair<String, String> {
public PairView(String first, String second) {
super(first, second);
}
public String toString() {
return second;
}
}
public class PairAdapter extends ArrayAdapter<PairView> {
}
So now I can put my id in pair.first and what to display to the user in pair.second.
My problem comes in that some of these options will be single-selects and some will be multi-selects. In html, that's not an issue, just use a checkbox group for multi, and radio buttons/dropdowns for single selects. In android however, it seems it's not so straight forward. I tried using Spinners for the adapters, but Spinner seems to only allow single selection. AlertDialog.Builder allows for single and multi-selections, but curiously I don't see an option for using an adapter for the multi-selection, just for single selections.
I guess what I really want is a consistent look for all my options, with radio buttons displayed for single selections and checkboxes displayed for multi selections, via an adapter so I can get the id's from the Pair for the items selected.
What approach should I use? A custom spinner with code added for multi-selections? AlertDialog.Builder and somehow make it use an adapter for multi-selections? Just create a plain Alert and wrap a ListView in it? Another option that is (hopefully) simpler?
I feel like I'm missing something very basic here.

I had a similar situation in an app I was making so would share what I opted for. I had different type of questions and depending on that I removed and added things in my activity. For radio buttons I used with elements in it. For multiple choice questions I wanted a checkbox based view so I added an empty within my layout and in code added CheckBox(s) to it.
As for the caption and value, for radio buttons and checkboxes you can set display text by setText and add any object/value as a tag. So what I used to do was something like this:
CheckBox option = new CheckBox(MyActivity.this);
option.setText("Option 1");
option.setTag(10);
Later on when you get the selected option, you can simply get its tag and use its value.
This is just one way of doing it which I found simple. Hope this helps

Can I have an android activity run only on the first time an application is opened?

OK, so I'm playing around with an android app.
The 90% use case is that users want to go straight to the primary list screen to find what they're looking for. That's what I want as my default screen.
The first time a user loads the app however, some configuration is required before their list screen is of any value to them.
So my question, is how I can go about displaying the configuration activity the first time the app is opened up, and then the list screen for future openings.
I also want to put a demo button on the configuration screen, so I suppose more than just detecting that it's the first time, I specifically want to detect whether the user has performed certain configurations within the first screen.

After the first time the user has loaded the app you could store the details of whether user has performed the configurations in SharedPreferences.
protected void storeSharedPrefs(String value) {
/*
* Storing in Shared Preferences
*/
editor.putString("first", value);
editor.commit(); //Commiting changes
}
Check each on time application is loaded, whether its the first time and configuration details has been entered correctly by checking SharedPreferences
private boolean first_time_check() {
/*
* Checking Shared Preferences if the user had pressed
* the remember me button last time he logged in
* */
String first = uPreferences.getString("first", null);
if((first == null)){
return false;
}
else
return true;
}

i like dweebsonduty's method. a similar way to do this is to save their configuration information in files on the SD card. your app could start out by checking for those files and loading the information. if the load is successful, it moves on to the next activity, if not it starts the appropriate activity to prompt the user for input.
I have done this same thing, but instead of swiching activities i just switch views until i have all the info i need, and then move on.

Many applications actually store the current version in SharedPreferences, and check against it for if an update has been installed. Its a clever way of achieving a "what's changed" popup, or making sure that some settings get set (I would be wary of just having a boolean flag because if you ever want to add an additional setting, you will need a second flag and it gets messy after the third, etc.).

String VersionValue = "v.1.0";
final String PREFS_NAME = "MyPrefsFile";
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
if (settings.getBoolean(VersionValue, true)) {
//the app is being launched for first time, do something
NewDialogFragment newFragment = new NewDialogFragment();
newFragment.show(getFragmentManager(), "New");
// record the fact that the app has been started at least once
settings.edit().putBoolean(VersionValue, false).commit();
}
You could do it this way and still get the same result I tried it its a small workaround if u do not fully understand how to check if the app is updated. Instead with this code you can just simply change the String VersoinValue to your current app version and android will think the app is a new first time app and will only display the code u wrote once until you change VersionValue on your next update. (:

How will you be storing the configuration?
If it is in SQLlite you could just create a table called firstuse and put a field in there called hasbeenused and make it null. Then when the app is used you can put a 1 in there. Then you can read it each time your app loads and if that field = 1 then go to your next activity.