Develop Reference

SharedPreferences not saving all the data after restart

I am new to Android App Development and I am supposed to make a TodoList App for a course. But the SharedPreference in my code is not working. I dont know if I'm supposed to use it in a specific way in a specific method like onCreate or onStop.
It is saving the first input the user is entering permanently, but in the same position:
(The "task0" is what I used to track the different variable names I used as argument for "putString" in addStuff method, to avoid replacing values)
It is saving the inputs after that in the same session, but if the user ends that session, all those values after "t" are gone. If the user restarts the app and inputs something else (like "g"), it is saving "g" in that same 3rd position.
I have basic Java knowledge and I tried to understand what is going on using it, but failed. Please let me know where is the mistake and how to use SharedPreferences properly.
public class TodoActivity extends AppCompatActivity {
public ArrayList<String> items;
public ArrayAdapter<String> itemsAdapter;
public ListView list;
public String s;
public EditText taskBox;
public static final String filename = "itemsList";
public TextView text;
public static int counter = 0;//counter starting at 0 no matter what, everytime the app starts
public String newtask= "task";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_todo);
list = (ListView) findViewById(R.id.list1);text = (TextView) findViewById(R.id.text1);
taskBox = (EditText) findViewById(R.id.box);
s = taskBox.getText().toString();
items = new ArrayList<String>();
itemsAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items);
list.setAdapter(itemsAdapter);
//add items to list
items.add("First Item");
items.add("Second Item");
//restore
SharedPreferences sp = this.getSharedPreferences("itemsList", 0);
//checking if it stores the previous values, this gives the last input but not the previous ones after restarting the app
String dummyname = "task";
text.setText(String.valueOf(counter));//since counter is again at
for(int c=0; c<=50; c++){
String num = String.valueOf(c);
dummyname = dummyname + num;
String x = sp.getString(dummyname, "not found");
if (x.equalsIgnoreCase("not found")){
counter=c-1;
break;
} else {
items.add(x);
text.setText(dummyname);
}
}
}
public void addItem(View v){
s = taskBox.getText().toString();
itemsAdapter.add(s);//adding the new task as string
String temp = String.valueOf(counter);
newtask = "task" + temp;
//trying to store the new tasks with different variable names to avoid being replaced
text.setText(newtask);
SharedPreferences sp = this.getSharedPreferences("itemsList", 0);
SharedPreferences.Editor e = sp.edit();
e.putString(newtask,s);
e.apply();
counter++;
}
}

If you have relatively small collection of key-values that you would like to save,
You should use Shared preference API
Read from the shared preference:
Pass the key and value you want to write,create a SharedPreferences.Editor by calling edit() on your SharedPreferences.
Pass key and values you want to save by using this method putInt() ,putString() ,Then call commit() to save the changes. For example:
SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt("KeyName", newHighScore);
editor.commit();
Write from the shared preference:
To retrieve values from a shared preferences file, call methods such as getInt() and getString(),
providing the key for the value you want, and optionally a default value to return if the key isn't present. For example:
SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
int defaultValue = getResources().getInteger(R.string.saved_high_score_default);
long highScore = sharedPref.getInt("KeyName", defaultValue);

Two things :
1) To initialize SharedPreferences use :
sharedPreferences = getSharedPreferences("itemsList", Context.MODE_PRIVATE);
2) Where are you calling addItem() method??

The problem is about the Tag you use to save items. See this Line :
dummyname = dummyname + num;
You add item by this format :
task0
task1
task2
but you are getting values in this format
task0
task01
task012
Just change these two line of code :
//dummyname = dummyname + num;
//String x = sp.getString(dummyname, "not found");
String newDummy= dummyname + num;
String x = sp.getString(newDummy, "not found");

After spliting String into ArryList<String> i cannot read the text from any cell

I am an android noobie. What I am trying to do is to make this String an ArrayList. This is done. When i Print it On (with tv.setText) , the result is what i need but in this if i have right below i cannot find the "1".
The result i want to have is to store the text between the noumbers inside another ArrayList but to go there i have to be able to read the strings from the ArrayList.
public class MainActivity extends AppCompatActivity {
String text = "1Hello12People22Paul22Jackie21Anna12Fofo2";
TextView tv;
List<String> chars = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView)findViewById(R.id.tv);
PrinThemNow();
}
public void PrinThemNow(){
chars = Arrays.asList(text.split(""));
tv.setText(toString().valueOf(chars));
for(int i=0;i<chars.size();i++){
if(toString().valueOf(chars.get(i)) == " 1"){
Toast.makeText(this,"I found One",Toast.LENGTH_LONG).show();
//This if is not working while the TV's text shows " 1"
}
}
}
}

First, just a tip, from string to char[] you can use
char[] chars = myString.toCharArray();
because it has no sense to save a char array as a string ArrayList
but now the problem. you have your string and you wanna print the text between the numbers.
It's not really clear what is your goal but lets try.
I will suppose you used the char[] because it's 10 times better and easier
case 1) you wanna print text betweens "1"s
//lets loop the chars
bool firstOneFound = false;
int firstOccurrence = -1;
int secondOccurrence = -1;
int i = 0;
for(char c : chars){
//is it equals to 1?
if(c.equals('1')){
//check if we are already after the first 1
if(firstOneFound){
//if yes, we found the final one
secondOccurrence = i;
break;
}
else{
//this is the first occurrence
firstOccurrence = i;
firstOneFound = true;
}
}
i++;
}
if(firstOccurrence != -1 && secondOccurrence != -1){
String myFinalString = myString.subString(firstOccurrence, secondOccurrence);
}
case 2) you wanna print all text except numbers (maybe with a space instead)
for(char c : chars){
//check if it's a number
if(c >= '0' && c <= '9'){
//replace the number with anything else
c = ' '; //if you wanna have it as a space
}
}
//print the final string
String myFinalString = new String(chars);
NOTE:
You can also use ArrayList of string, just replace ' with "
hope it helps

Passing strings to list and deleting them using shared preferences

i wish to, in one activity, put strings in the sharedpreferences, so then, in another activity, i get those strings, put them in a array and display them sequentially. I managed to do this, but i don`t have any idea how can i delete one specified string when asked. These strings will just be scattered on the shared preferences,and i dont know how to keep track of them. I can pass this unique int id to each element. I tried to use LinkedList, but i cannot pass this kind of structure as a shared preferences. I did not managed to make Gson work also. Please help.
Method that gets the string and put on shared preferences:
public void makefavorites(String[] a, String[] b, int id)
{
int idfinal = id%10;
idfinal = idfinal+1;
a[idfinal] = b[idfinal] +"\n" + "\n"+ a[idfinal];
SharedPreferences prefs = getSharedPreferences("Favorites", Activity.MODE_PRIVATE);
Editor edit = prefs.edit();
int temp = prefs.getInt("favorites_size", 0);
edit.putInt("favorites_size", temp+1);
edit.putString("array_" + prefs.getInt("favorites_size", 0), a[idfinal]);
edit.commit();
refreshfavorites();
}
Method that gets those strings, put on array and display it:
public void refreshfavorites()
{
SharedPreferences prefs = getSharedPreferences("Favorites", Activity.MODE_PRIVATE);
//GETS THE ARRAY SIZE
int size = prefs.getInt("favorites_size", 0);
String[] array = new String[size];
for(int i=0; i<size; i++){
array[i] = prefs.getString("array_" + i, null);
}
}

you have to use editor.remove method to delete specific value from arraylist..
public void removeArray(String[] list)()
{
SharedPreferences.Editor editor = mSharedPrefs.edit();
int size = list.length();
for (int i = 0; i < size; i++) {
editor.remove("favorites_size"+i);
}
editor.commit();
}
i hope its useful to you..

Array access producing unwanted result

I am getting an unusual result when attempting to place a value in an array.
I have an array table[] of a simple class result{ int score, long time, string ID}
Intention is to have a sort of leader board.
My code happily finds the correct place to insert a new score if it is in the top 10.
int ix = 0;
int jx = 10; //
while ( ix < jx )
{
if (points > sTable[ix].points)
{
// score is higher move records down
for (jx = mNumRecords - 1; jx >ix ; jx--)
{
sTable[jx] = sTable[jx -1];
}
//now add new score
sTable[ix].score = score; // all good until here
sTable[ix].time = time;
}
ix++;
}
Problem is that when I try to insert the score using sTable[ix].score = score;
The value gets written to sTable[ix].score and also sTable[ix +1].score.
It is repeatable, it occurs at any value of ix, I have single stepped through the code and as far as I can tell the command only executes once.
Has anyone seen this before?

That because you copied the object reference to the next element in the array. You should copy the values, or create a new object:
Option A:
// score is higher move records down
for (jx = mNumRecords - 1; jx >ix ; jx--)
{
sTable[jx].time = sTable[jx -1].time;
sTable[jx].score = sTable[jx -1].score;
}
//now add new score
sTable[ix].score = score; // all good until here
sTable[ix].time = time;
Option B:
for (jx = mNumRecords - 1; jx >ix ; jx--)
{
sTable[jx] = sTable[jx -1];
}
sTable[ix] = new Result(score, time, ""); // Or however you construct the object

String Array increment each string in TextToSpeech

Using the text to speech API I want to change the string array to increment from index 0 string and when it reaches the end it will go back to the beginning.
At the moment it uses a random generator and the method works as follows:
public static void sayHello() {
// Select a random hello.
int helloLength = HELLOS.length;
String hello = HELLOS[RANDOM.nextInt(helloLength)];
mTts.speak(hello,
TextToSpeech.QUEUE_FLUSH, // Drop all pending entries in the playback queue.
null);
}
HELLOS is the array and it holds the strings:
String [] HELLOS = {"One" "Two" "Three" "Four"};
Appreciate any help
Thanks.

When you want to increment an index but loop around to zero again modulo is your friend.
int currentHelloIndex = 0;
public static void sayHello() {
// Select a random hello.
int helloLength = HELLOS.length;
String hello = HELLOS[currentHelloIndex];
currentHelloIndex = (currentHelloIndex + 1) % helloLength;
mTts.speak(hello,
TextToSpeech.QUEUE_FLUSH, // Drop all pending entries in the playback queue.
null);
}