EditText 不由 SharedPreferences 保存

Question

I'm supposed to save three EditTexts' strings using SharedPreferences so I can use them in a TextView when user re-enter the app. This is what I have tried:

public class MainActivity extends AppCompatActivity {

    private EditText PrivName;
    private EditText LastName;
    private EditText LastMov;
    SharedPreferences sp;
    private Button SaveBtn;
    private TextView Text;
    String Priv, Lst, Mov;

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

        PrivName = (EditText)findViewById(R.id.PrivName);
        LastName = (EditText)findViewById(R.id.LastName);
        LastMov = (EditText)findViewById(R.id.LastMov);
        SaveBtn = (Button)findViewById(R.id.SaveBtn);
        Text = (TextView) findViewById(R.id.Message);

        sp = getSharedPreferences("Movies", Context.MODE_PRIVATE);

        SaveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Priv = PrivName.getText().toString();
                Lst = LastName.getText().toString();
                Mov = LastMov.getText().toString();

                SharedPreferences.Editor editor = sp.edit();

                editor.putString("Name", Priv);
                editor.putString("Name2", Lst);
                editor.putString("Movie", Mov);
                editor.commit();
            }
        });
        Text.setText("We hope that you  " + Priv + " "  +Lst + " enjoyed the movie: " + Mov);
    }
}

Obviously the problem is that when you click the button the TextView changes to what you want but when you re-enter the app everything resets instead of staying the same

Answer 1

You need to also read from the SharedPrefs, so you can actually fill the EditText. Try something like that:

Add this in your onCreate method

sp = getSharedPreferences("Movies", Context.MODE_PRIVATE);
PrivName.setText(sp.getString("Name", "")); //The empty string after the comma is a default value incase you don't a stored value for that key
LastName.setText(sp.getString("Name2", ""));
LastMov.setText(sp.getString("Movie", ""));

Answer 2

Invoke the following method at the end of your onCreate method.

private void showSavedValue()
{
  // Retaining the values from shared preferences
  String savedPrivName = sp.getString("Name",""); // If no value was stored previously it will return an empty string
  String savedLastName = sp.getString("Name2", "");
  String savedLastMovie = sp.getString("Movie","");

  //Write your code here to use these values where you want to use them


}

Note: Try to follow the recommended naming convention while writing Java. A detailed guide on Java naming conventions can be found here

Answer 3

Look at your source code properly what you are doing..

editor.putString("Name", Priv);
editor.putString("Name2", Lst);
editor.putString("Movie", Mov);
editor.commit();

Here you are saving some parameter.. Where "Name" is a id and, you are saving Priv strings to that id.. Same is happening to Name2 and Movie.

Priv = PrivName.getText().toString();
Lst = LastName.getText().toString();
Mov = LastMov.getText().toString();

You are getting texts from Edittexts and saving them to Priv,Lst,Mov . But, they aren't working as sharedPreferences. That means when you restart the application these values will be gone...

Text.setText("We hope that you  " + Priv + " "  +Lst + " enjoyed the movie: " + Mov);

In the above source code you are showing those values which will be gone if you restart. And, you wrote that code to onCreate method. So, when you are starting application these values are showing but, which has no value( null ).

Here what you should try.. @Niaz Ahmed 's answer is correct but, his explanation is very poor that's why I am posting another answer.

String savedPrivName = sp.getString("Name",""); // If no value was stored previously it will return an empty string


String savedLastName = sp.getString("Name2", "");
  String savedLastMovie = sp.getString("Movie","");

Text.setText("We hope that you  " + savedPrivName + " "  +savedLastName + " enjoyed the movie: " + savedLastMovie);