在文本视图中显示共享的首选项

Question

I'm trying to make a simple calculator app and want the final calculation result to not disappear once the app closes.

I can get the numbers that are inputted by the user to stay in place and the result is calculated correctly, however once the app closes the result disappears?!

Any help would be much appreciated!!

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.calculator);

    final SharedPreferences prefs = PreferenceManager
            .getDefaultSharedPreferences(this);

    editText3.setText(prefs.getString("autoSave", ""));
    editText4.setText(prefs.getString("autoSave1", ""));
    editText6.setText(prefs.getString("autoSave2", ""));
    editText8.setText(prefs.getString("autoSave3", ""));



    editText3.addTextChangedListener(new TextWatcher() {

        public void beforeTextChanged(CharSequence s, int start, int count,
                                      int after) {

        }

        public void onTextChanged(CharSequence s, int start, int before,
                                  int count) {
            textViewResult.setText(addNumbers());
        }


        public void afterTextChanged(Editable s)
        {
            prefs.edit().putString("autoSave", s.toString()).commit();
        }


    });

    editText4.addTextChangedListener(new TextWatcher() {

        public void beforeTextChanged(CharSequence s, int start, int count,
                                      int after) {

        }

        public void onTextChanged(CharSequence s, int start, int before,
                                  int count) {
            textViewResult.setText(addNumbers());

        }

        public void afterTextChanged(Editable s)
        {
            prefs.edit().putString("autoSave1", s.toString()).commit();
        }
    });

    editText6.addTextChangedListener(new TextWatcher() {

        public void beforeTextChanged(CharSequence s, int start, int count,
                                      int after) {


        }

        public void onTextChanged(CharSequence s, int start, int before,
                                  int count) {
            textViewResult.setText(addNumbers());

        }

        public void afterTextChanged(Editable s)
        {
            prefs.edit().putString("autoSave2", s.toString()).commit();
        }
    });

    editText8.addTextChangedListener(new TextWatcher() {

        public void beforeTextChanged(CharSequence s, int start, int count,
                                      int after) {


        }

        public void onTextChanged(CharSequence s, int start, int before,
                                  int count) {
            textViewResult.setText(addNumbers());

        }

        public void afterTextChanged(Editable s)
        {
            prefs.edit().putString("autoSave3", s.toString()).commit();
        }
    });
}

private String addNumbers() {
    int number1;
    int number2;
    int number3;
    int number4;
    if (editText3.getText().toString() != "" && editText3.getText().length() > 0) {
        number1 = Integer.parseInt(editText3.getText().toString());
    } else {
        number1 = 0;
    }
    if (editText4.getText().toString() != "" && editText4.getText().length() > 0) {
        number2 = Integer.parseInt(editText4.getText().toString());
    } else {
        number2 = 0;
    }
    if (editText6.getText().toString() != "" && editText6.getText().length() > 0) {
        number3 = Integer.parseInt(editText6.getText().toString());
    } else {
        number3 = 0;
    }
    if (editText8.getText().toString() != "" && editText8.getText().length() > 0) {
        number4 = Integer.parseInt(editText8.getText().toString());
    } else {
        number4 = 0;
    }

    int sum = (number1 * 2) + (number2 * 4) + (number3 * 2) + (number4 * 2);
    if (sum > 6) sum = 6;
    return sum + "";

} }

Answer 1

您可以将结果保存在将计算结果显示在文本视图中的位置，然后保存所保存的内容以及向用户显示的内容

Answer 2

Initialize your SharedPreference as follows,

SharedPreferences prefs = this.getSharedPreferences(
      "com.example.app", Context.MODE_PRIVATE);

Answer 3

Try this,

First, save your result to preferences in addNumbers method using

prefs.edit().putString("result", sum.toString()).commit();

See the Changes to your addNumbers method below-:

private String addNumbers() {
int number1;
int number2;
int number3;
int number4;
if (editText3.getText().toString() != "" && editText3.getText().length() > 0) {
    number1 = Integer.parseInt(editText3.getText().toString());
} else {
    number1 = 0;
}
if (editText4.getText().toString() != "" && editText4.getText().length() > 0) {
    number2 = Integer.parseInt(editText4.getText().toString());
} else {
    number2 = 0;
}
if (editText6.getText().toString() != "" && editText6.getText().length() > 0) {
    number3 = Integer.parseInt(editText6.getText().toString());
} else {
    number3 = 0;
}
if (editText8.getText().toString() != "" && editText8.getText().length() > 0) {
    number4 = Integer.parseInt(editText8.getText().toString());
} else {
    number4 = 0;
}

int sum = (number1 * 2) + (number2 * 4) + (number3 * 2) + (number4 * 2);
if (sum > 6) sum = 6;
prefs.edit().putString("result", sum.toString()).commit();
return sum + "";

  } 
}

Where result is your key. so to get the value which you have stored you can use prefs with the same key like

prefs.getString("result","");

Get the value from preference in onCreate and set this value to your TextView . See the sample code below

@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    setContentView(R.layout.calculator);

    final SharedPreferences prefs = PreferenceManager
            .getDefaultSharedPreferences(this);

    String result= prefs.getString("result",""); //where "" is your default value
    if(!result.equals("") && !result.isEmpty()){
      textViewResult.setText(addNumbers());
    }


/*other code*/

Answer 4

You can do this like bellow..

1. Create a method to save SharedPreferences

     private void savePreferences(String key, String value) { SharedPreferences sp = PreferenceManager .getDefaultSharedPreferences(this); Editor edit = sp.edit(); edit.putString(key, value); edit.commit(); } 

2. Save value to method like

    savePreferences("autosave", s.toString()); 

3. View data form from SharedPreferences , Create another method like

    private void loadSavedPreferences() { SharedPreferences sp = PreferenceManager .getDefaultSharedPreferences(this); String autosave = sp.getString("autosave", ""); editText3.setText(autosave); } 

4. Call loadSavedPreferences method in oncreate mehtod in activity & enjoy it... Thanks...