重新启动应用程序时，如何在 EditText 中保留字符串/整数值？

Question

In my Android activity, I have one EditText , a ' + ' button, a ' - ' button, ' Save ' button and ' Load ' button. When I press ' + ', the value in EditText increases by 1, similarly on pressing ' - ' value decreases by 1. I used SharedPreferences to save the data when I click on ' Save '. When I click ' Load ', I want to reload this data onto the EditText field.

Now the problem is, when I completely exit the application (even from recently used apps), and click ' Load ' on relaunching it, the saved number doesn't appear. I included the onClick() action for the 'Load' method in onRestart() method. It still doesn't work. What am I missing here? I even tried out all other suggestions for the similar questions asked previously here. Also, is it really onRestart() or onRestoreInstanceState() ?

public class MainActivity extends Activity {
    Button btn1;
    Button btn2;
    Button btn3;
    Button btn4;
    EditText scoreText;
    int counter = 0;
    TextView textTitle;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn1 = (Button)findViewById(R.id.add);
        btn2 = (Button)findViewById(R.id.subtract);
        btn3 = (Button)findViewById(R.id.save);
        btn4 = (Button)findViewById(R.id.load);
        scoreText = (EditText)findViewById(R.id.total);
        textTitle = (TextView)findViewById(R.id.title);

        btn1.setOnClickListener(new View.OnClickListener() {
            // The code in this method will be executed when the numbers View is clicked on.
            @Override
            public void onClick(View v) {
                counter++;
                scoreText.setText(Integer.toString(counter));
                scoreText.setBackgroundColor(Color.GREEN);
            }
        });

        btn2.setOnClickListener(new View.OnClickListener() {
            // The code in this method will be executed when the numbers View is clicked on.
            @Override
            public void onClick(View v) {
                counter=counter-1;
                scoreText.setText(Integer.toString(counter));
                scoreText.setBackgroundColor(Color.RED);
            }
        });
        btn3.setOnClickListener(new View.OnClickListener() {
            // The code in this method will be executed when the numbers View is clicked on.
            @Override
            public void onClick(View v) {
                //store data using sharedprefernces
                SharedPreferences sharedPreferences=getSharedPreferences("Data", Context.MODE_PRIVATE);
                SharedPreferences.Editor editor=sharedPreferences.edit();
                //Edit method allow to write the data in sharedpreferences
                editor.putString("count",scoreText.getText().toString());
                //For commit changes commit() method is used
                editor.commit();
                Toast.makeText(getApplicationContext(),"Data Saved",Toast.LENGTH_SHORT).show();
            }
        });
        btn4.setOnClickListener(new View.OnClickListener() {
            // The code in this method will be executed when the numbers View is clicked on.
            @Override
            public void onClick(View v) {
                SharedPreferences sharedPreferences=getSharedPreferences("Data", Context.MODE_PRIVATE);
                String strcount=sharedPreferences.getString("name",scoreText.getText().toString());
               // scoreText.setText(strcount);
                scoreText.setBackgroundColor(Color.YELLOW);
            }
        });

    }

    @Override
    protected void onRestart(Bundle savedInstanceState){
        super.onRestart(savedInstanceState);
        btn4.setOnClickListener(new View.OnClickListener() {
            // The code in this method will be executed when the numbers View is clicked on.
            @Override
            public void onClick(View v) {
                SharedPreferences sharedPreferences=getSharedPreferences("Data", Context.MODE_PRIVATE);
                String strcount=sharedPreferences.getString("name",scoreText.getText().toString());
                if (strcount.equals(""))
                {
                    Toast.makeText(getApplicationContext(), "Data Was Not Found", Toast.LENGTH_SHORT).show();
                }
                else
                {
                    scoreText.setText(strcount);


                }
                scoreText.setBackgroundColor(Color.YELLOW);
            }
        });

    }

Answer 1

You using using count as key to save the value

editor.putString("count",scoreText.getText().toString());

but using name as key to retrieve the value so you need to use count key while getting the previously stored data so use

sharedPreferences.getString("count",scoreText.getText().toString());

instead of

sharedPreferences.getString("name",scoreText.getText().toString());

Answer 2

You are using different keys to save and retrieve the data from SharedPrefernces.

editor.putString("count",scoreText.getText().toString());
String strcount=sharedPreferences.getString("name",scoreText.getText().toString());

You should be using the same key in both the cases otherwise it would return default value which is the text in TextView and that would be empty at the start of the app, you just need to change the key and that would do the trick for you.

Just change the below line like it is mentioned

String strcount=sharedPreferences.getString("count",scoreText.getText().toString());