Whats make value of variable become empty or back to initialization value in lifecycle

Issue

I just curious what makes a value inside of some variable become empty again or back to its initial value in the android life cycle.

First lets take a look at how i create a variable :

public class myData {
 public static String myCode = "";

 public static String getData(String Choice) {
  String theData = "";
  if ("Code".equals(Choice) {
   theData = myCode;
  }

  return myCode;
 }

 public static void setData(String setData,String Choice) {

  if ("Code".equals(Choice) {
   myData.myCode = setData;
  } 
 }
}

If I want to fill the variable, i usually do this :

myData.setData("value of variable","Code");

And if I want to get the value of the variable, I usually do this :

myData.getData("Code");

I just want to know what makes my variable gone inside of android lifecycle, of course excluding when the application is closed.

I have to try to Log and show the value in onstart , oncreate, onresume and onrestart. And all of them is still have the value inside of my variable intact without any problem.

My client always tells me that my application sometimes gets crash when they open some activity. I also ask if they did something while using my application,

some of them answer that the application get crashed after they got a phone call and when the phone call is ended, the application is started with a crash.

some of them also said that when they open the application and then idle the phone withouth closing the application until the phone become black screen, and when they open it again the application get crashed.

After I check the log, the problem was the variable become empty. which is why I want to know is there another possibilites that makes the value inside of the variable become empty?

Solution

As John Lord saying, on low-end device variables might back to its initial value again if there is not enough memory.

So for future reference, I use a shared preference to counter it, here is my structure for fetching the data :

public class myActivity extends AppCompatActivity {

  String myCode = "";

  protected void onCreate(Bundle savedInstanceState) {
   ....
     SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences("myData", Context.MODE_PRIVATE);
     myCode = sharedPreferences.getString("Code",null);
   ....
  }

  @Override
  protected void onResume() {
        super.onResume();
        SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences("myData", Context.MODE_PRIVATE);
        myCode = sharedPreferences.getString("Code",null);
  }


}

And here is how i set the data :

SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences("myData",Context.MODE_PRIVATE);

sharedPreferences.edit().putString("Code","Hello World").apply();

I hope it will be helpful for those who want to search the same thing

Answered By - hakim homecent