I am trying to pass a String from a class (UserInput) to Main Activity and display it in a TextView. User is supposed to press a button in Main Activity, which calls UserInput and enter a String. Using Shared Preferences, I managed to pass the String over, but could not get it to display in the TextView.

I realized that the getSharedPreference and setText part was done before the class was started, resulting in the TextView not being updated after returning from UserInput and I have no idea how to solve this issue. Any help will be much appreciated. Thanks!

Main Activity code

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

TextView tvCode;
Button btnCode, btnClear;
TextInputLayout textInputMessage;
String preferenceFileName, preferenceKey, retreivedCodeString;

@Override
protected void onCreate(Bundle savedInstanceState) 
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);

 tvCode = findViewById(R.id.textViewCode);
 btnCode = findViewById(R.id.buttonCode);
 btnClear = findViewById(R.id.buttonClear);
 textInputMessage = findViewById(R.id.textInputLayoutMessage);
 preferenceFileName = "PreferenceFile";
 preferenceKey = "CodeKey";


 SharedPreferences sharedPreferences = getSharedPreferences(preferenceFileName, MODE_PRIVATE);
 retreivedCodeString = sharedPreferences.getString(preferenceKey,"");
 tvCode.setText(retreivedCodeString);

 btnCode.setOnClickListener(this);
 btnClear.setOnClickListener(this);



@Override
public void onClick(View arg0) 
 switch (arg0.getId())
 case R.id.buttonClear:
 //method
 break;
 case R.id.buttonCode:
 Intent intent = new Intent(this, UserInput.class);
 startActivity(intent);
 sharedPreferences = getSharedPreferences(preferenceFileName, MODE_PRIVATE);
 retreivedCodeString = sharedPreferences.getString(preferenceKey,"");
 tvCode.setText(retreivedCodeString);
 break;
 

UserInput code

public class UserInput extends Activity implements View.OnClickListener {
String userInputCode, preferenceFileName, preferenceKey;
TextInputLayout subTextInputLayoutCode;

@Override
protected void onCreate(Bundle savedInstanceState)
 super.onCreate(savedInstanceState);
 setContentView(R.layout.code);

 subTextInputLayoutCode = findViewById(R.id.textInputLayoutCode);
 Button btnOk = findViewById(R.id.buttonOk);
 Button btnCancel = findViewById(R.id.buttonCancel);
 preferenceFileName = "PreferenceFile";
 preferenceKey = "CodeKey";

 btnOk.setOnClickListener(this);
 btnCancel.setOnClickListener(this);


@Override
public void onClick(View arg0) 
 switch (arg0.getId())
 case R.id.buttonOk:
 if (!validateCode())
 return;
 
 userInputCode = subTextInputLayoutCode.getEditText().getText().toString();
 SharedPreferences sharedPreferences = getSharedPreferences(preferenceFileName, MODE_PRIVATE);
 SharedPreferences.Editor editor = sharedPreferences.edit();
 editor.putString(preferenceKey,userInputCode);
 editor.apply();
 finish();
 break;
 case R.id.buttonCancel:
 finish();
 break;
 

Way 1:

use below code in onResume method of your MainActivity

SharedPreferences sharedPreferences = getSharedPreferences(preferenceFileName, MODE_PRIVATE);
retreivedCodeString = sharedPreferences.getString(preferenceKey,"");
tvCode.setText(retreivedCodeString);

Way 2:

start your UserInput activity for result (startActivitForResult(intent, 123))

and finish your UserInput activity using below code

setResult(Activity.RESULT_OK)
finish()

in your main activity override onActivityResultMethode like below

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) 
 if(requestCode == 123 && resultCode == Activity.RESULT_OK)
 SharedPreferences sharedPreferences = getSharedPreferences(preferenceFileName, MODE_PRIVATE);
 retreivedCodeString = sharedPreferences.getString(preferenceKey,"");
 tvCode.setText(retreivedCodeString);
 else 
 super.onActivityResult(requestCode, resultCode, data)
 

Way 3: (without sharedPreferences )

start your UserInput activity for result (startActivitForResult(intent, 123))

and finish your UserInput activity using below code

Intent i = new Intent();
Bundle b = new Bundle();
b.putString("inputText", YOUR_INPUT_TEXT);
i.putExtras(b);
setResult(123, i)
finish()

in your main activity override onActivityResultMethode like below

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) 
 if(requestCode == 123 && resultCode == Activity.RESULT_OK)
 tvCode.setText(data.getExtras().getString("inputText",""));
 else 
 super.onActivityResult(requestCode, resultCode, data)