android将值存储在数组或列表中而不覆盖

Question

我只是想知道是否有一种方法可以将数据保存到文本文件中而不会被覆盖。

目前我正在使用 sharedpreferences，它会覆盖数据，这没关系，但与此一致，我想要在某个地方记录值，然后再以列表或列的形式覆盖。

所以它是这样的： 60、65、70..等 这些值一个接一个地存储而不会被覆盖。我正在考虑在一个可以读取的文本文件中本地执行此操作。

我这样做是为了创建一个统计页面或类似的东西。

希望有人能帮我找到解决办法。

我的代码：

public class workout extends Activity {

    TextView weightresultText, newweightresultText, difficultyrating;
    Boolean male, strength;
    double newweight, newweight1;
    int weight, age;
    Button button, button4;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.workout);
        button = (Button) findViewById(R.id.button);
        button4 = (Button) findViewById(R.id.button4);

        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        weight = Integer.parseInt(sharedPreferences.getString("storedweight", "Your Weight"));
        age = Integer.parseInt(sharedPreferences.getString("storedage", "Your Age"));
        male = sharedPreferences.getBoolean("is_male", false);
        strength = sharedPreferences.getBoolean("is_strength", false);

        weightresultText = (TextView) findViewById(R.id.weightresultLabel);
        newweightresultText = (TextView) findViewById(R.id.newweightresultLabel);
        difficultyrating = (TextView) findViewById(R.id.difficultylevel);

         if (sharedPreferences.getBoolean("firstrun", true)) {AgeCalculation();

             sharedPreferences.edit().putBoolean("firstrun", false).commit();}


        AfterFirstLaunch();
    }

    public void SaveWeight(){
        savePreferences("storednewweight", (Double.toString(newweight)));
    }

//Should only happen on first launch.
    public void AgeCalculation() {
        if (strength == true){
        if (male == true && age >= 18) {
            newweight = (weight * 0.8);
            }
        if (male == true && age >= 30) {
            newweight = (weight * 0.6);
        }
        if (male == true && age >= 50) {
            newweight = (weight * 0.4);
        }
        if (male == true && age >= 70) {
            newweight = (weight * 0.2);
        }
        if (male == true && age > 80) {
            newweight = (weight * 0.1);
        }
        if (male == false && age >= 20 ){
            newweight = (weight * 0.3 );
                    }
        weightresultText.setText(Double.toString(newweight));
        SaveWeight();
            }}

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

// On every other launch, it is based on button, the newweight is saved and loaded each time.
    public void buttonClick1(){
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View arg0) {

            //this gets the current weight based on first time launch.
            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
            String newweight =  sharedPreferences.getString("storednewweight", "");

           newweight1 = Double.parseDouble(newweight);

            newweight1 = newweight1 + 5;
            //saves value into sharedpreference
            savePreferences("storednewweight", (Double.toString(newweight1)));
            //save to shared preference, and load value on new launch?
            //also store into local database for review later.
            difficultyrating.setText("1");
            button.setEnabled(false);
            button4.setEnabled(false);

           //save this data then on new launch it uses this figure.
            // so first time it creates then uses this figure for future.
        }

    });}

    public void buttonClick4(){
        button4.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {

                //this gets the current weight based on first time launch.
                SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
                String newweight =  sharedPreferences.getString("storednewweight", "");

                newweight1 = Double.parseDouble(newweight);

                newweight1 = newweight1 + 10;
                //saves value into sharedpreference
                //save to text file in array
                savePreferences("storednewweight", (Double.toString(newweight1)));

                difficultyrating.setText("2");
                button.setEnabled(false);
                button4.setEnabled(false);

                //save this data then on new launch it uses this figure.
                // so first time it creates then uses this figure for future.
            }

        });}

    //runs on every other launch
    public void AfterFirstLaunch(){

        buttonClick1();
        buttonClick4();
        //receive value on other launches and show on field.
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        String newweight =  sharedPreferences.getString("storednewweight", "");
        weightresultText.setText(newweight);

    }



        }

Answer 1

对于这样的事情，您要存储多个类似数据的条目，您确实希望将 SQL 数据库与内容提供程序一起使用。您只需为每个条目创建新行。

Answer 2

要写入一个被覆盖的文本文件，请使用以下代码

File sdCard = Environment.getExternalStorageDirectory();
String path = sdCard.getAbsolutePath() + "/SO/";

File dir = new File(path);
    if (!dir.exists()) {
        if (dir.mkdirs()) {

    }
}

File logFile = new File(path + "filename.txt");
        if (!logFile.exists()) {
            logFile.createNewFile();
        }

        // BufferedWriter for performance, true to set append to file

        FileWriter fw = new FileWriter(logFile, true);
        BufferedWriter buf = new BufferedWriter(fw);


        buf.append("Message");
        buf.newLine();
        buf.flush();


        buf.close();

确保您在AndroidManifest.xml 中定义了权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />