Android将字符串添加到共享偏好设置

时间：2017-05-17 21:42:07

标签： android string sharedpreferences

我的任务是编写简单的应用程序：

1。用户在文本字段中写入字符串并将其保存到SharedPreferences（他的注释）

    saveButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            text = textEtxt.getText().toString();

            InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(textEtxt.getWindowToken(), 0);

            // save to ShPr
            sharedPreference.save(context, text);
            Toast.makeText(context,
                    getResources().getString(R.string.saved),
                    Toast.LENGTH_LONG).show();


        }
    });

2。在SharedPreferences类中保存对象

public void save (Context context, String text) {

    SharedPreferences settings;
    Editor editor;
    settings = PreferenceManager.getDefaultSharedPreferences(context);
    settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    editor = settings.edit();

    editor.putString(PREFS_KEY, text);

    editor.commit();

}

3。在SharedPreference类中获取对象

public String getValue(Context context) {

    SharedPreferences settings;
    String text;
    settings = PreferenceManager.getDefaultSharedPreferences(context);
    settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    text = settings.getString(PREFS_KEY, null);
    return text;
}

4. 阅读用户之前已写过的所有笔记（在其他活动中）​​

protected void onCreate (Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.second);
    sharedPreference = new SharedPreference();
    findViewsById();
    text += sharedPreference.getValue(context);
    textTxt.append(text);

}

我的问题：我的程序总是覆盖旧的字符串，所以我在阅读活动中只能有1个（最新的注释）。我错在哪里或者我能做些什么来保持我的字符串被添加到存在中？

5 个答案:

答案 0 :(得分：0)

使用HashSet将notes存储到SharedPreferences。

＃。将notes存储到SharedPreferences：

public static final String PREFS_KEY = "notes";

............
.................
public void saveNote(Context context, String text) {

    SharedPreferences settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = settings.edit();

    // Get existing notes
    Set<String> notes = getNotes();

    // Add new note to existing notes
    notes.add(text);

    // Store notes to SharedPreferences
    editor.putStringSet(PREFS_KEY, notes);
    editor.apply();
}

＃。从notes获取SharedPreferences：

public Set<String> getNotes(Context context) {

    SharedPreferences settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);

    // Get notes
    Set<String> notes = settings.getStringSet(PREFS_KEY, new HashSet<String>());

    return notes;
}

＃。阅读notes中的所有SharedPreferences并在TextView上显示：

protected void onCreate (Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.second);

    sharedPreference = new SharedPreference();
    findViewsById();

    // Get notes
    ArrayList<String> noteList = new ArrayList<String>(sharedPreference.getNotes(context));

    StringBuilder stringBuilder = new StringBuilder();

    // Looping through all notes and append to StringBuilder
    for(int i = 0; i < noteList.size(); i++)
        stringBuilder.append("\n" + noteList.get(i));

    // Set note text to your TextView   
    textView.setText(stringBuilder.toString());
}

希望这会有所帮助〜

答案 1 :(得分：0)

我创建了一个类，其中包含一些通用的代码方法，可以在我的应用程序中使用，以节省我的时间。所以我不必一次又一次地做同样的事情。将此Helper类放在代码中的任何位置，并访问它在您的应用程序中使用的方法。它有许多帮助方法，您可以根据您的要求在任何应用程序中使用它们。在项目中处理此类之后，您可以通过“Helper.anymethod（）”轻松访问它的方法。对于共享首选项，它具有名为“saveData（）”和“getSavedData（）。

的方法 
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.SharedPreferences;
import android.support.v4.app.FragmentActivity;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;
import android.widget.Toast;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

public class Helper {

private static ProgressDialog pd;

public static void saveData(String key, String value, Context context) {
    SharedPreferences sp = context.getApplicationContext()
            .getSharedPreferences("appData", 0);
    SharedPreferences.Editor editor;
    editor = sp.edit();
    editor.putString(key, value);
    editor.commit();
}

public static void deleteData(String key, Context context){
    SharedPreferences sp = context.getApplicationContext()
            .getSharedPreferences("appData", 0);
    SharedPreferences.Editor editor;
    editor = sp.edit();
    editor.remove(key);
    editor.commit();

}

public static String getSaveData(String key, Context context) {
    SharedPreferences sp = context.getApplicationContext()
            .getSharedPreferences("appData", 0);
    String data = sp.getString(key, "");
    return data;

}




public static long dateToUnix(String dt, String format) {
    SimpleDateFormat formatter;
    Date date = null;
    long unixtime;
    formatter = new SimpleDateFormat(format);
    try {
        date = formatter.parse(dt);
    } catch (Exception ex) {

        ex.printStackTrace();
    }
    unixtime = date.getTime();
    return unixtime;

}

public static String getData(long unixTime, String formate) {

    long unixSeconds = unixTime;
    Date date = new Date(unixSeconds); 
    SimpleDateFormat sdf = new SimpleDateFormat(formate);  
    String formattedDate = sdf.format(date);
    return formattedDate;
}

public static String getFormattedDate(String date, String currentFormat,
        String desiredFormat) {
    return getData(dateToUnix(date, currentFormat), desiredFormat);
}




public static double distance(double lat1, double lon1, double lat2,
        double lon2, char unit) {
    double theta = lon1 - lon2;
    double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
            + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2))
            * Math.cos(deg2rad(theta));
    dist = Math.acos(dist);
    dist = rad2deg(dist);
    dist = dist * 60 * 1.1515;
    if (unit == 'K') {
        dist = dist * 1.609344;
    } else if (unit == 'N') {
        dist = dist * 0.8684;
    }
    return (dist);
}

/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts decimal degrees to radians : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double deg2rad(double deg) {
    return (deg * Math.PI / 180.0);
}

/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts radians to decimal degrees : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double rad2deg(double rad) {
    return (rad * 180.0 / Math.PI);
}

public static int getRendNumber() {
    Random r = new Random();
    return r.nextInt(360);
}

public static void hideKeyboard(Context context, EditText editText) {
    InputMethodManager imm = (InputMethodManager) context
            .getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(editText.getWindowToken(), 0);
}

public static void showLoder(Context context, String message) {
    pd = new ProgressDialog(context);

    pd.setCancelable(false);
    pd.setMessage(message);
    pd.show();
}

public static void showLoderImage(Context context, String message) {
    pd = new ProgressDialog(context);
    pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    pd.setCancelable(false);
    pd.setMessage(message);
    pd.show();
}

public static void dismissLoder() {
    pd.dismiss();
}

public static void toast(Context context, String text) {

    Toast.makeText(context, text, Toast.LENGTH_LONG).show();
}
/*
public static Boolean connection(Context context) {
    ConnectionDetector connection = new ConnectionDetector(context);
    if (!connection.isConnectingToInternet()) {

        Helper.showAlert(context, "No Internet access...!");
        //Helper.toast(context, "No internet access..!");
        return false;
    } else
        return true;
}*/

public static void removeMapFrgment(FragmentActivity fa, int id) {

    android.support.v4.app.Fragment fragment;
    android.support.v4.app.FragmentManager fm;
    android.support.v4.app.FragmentTransaction ft;
    fm = fa.getSupportFragmentManager();
    fragment = fm.findFragmentById(id);
    ft = fa.getSupportFragmentManager().beginTransaction();
    ft.remove(fragment);
    ft.commit();

}

public static AlertDialog showDialog(Context context, String message) {
    AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setMessage(message);

    builder.setPositiveButton("OK", new OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int id) {
            // TODO Auto-generated method stub

        }
    });

    return builder.create();
}

public static void showAlert(Context context, String message) {
    AlertDialog.Builder builder = new AlertDialog.Builder(context);
    builder.setTitle("Alert");
    builder.setMessage(message)
            .setPositiveButton("Ok", new OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.dismiss();
                }
            }).show();
}

public static boolean isURL(String url) {
    if (url == null)
        return false;

    boolean foundMatch = false;
    try {
        Pattern regex = Pattern
                .compile(
                        "\\b(?:(https?|ftp|file)://|www\\.)?[-A-Z0-9+&#/%?=~_|$!:,.;]*[A-Z0-9+&@#/%=~_|$]\\.[-A-Z0-9+&@#/%?=~_|$!:,.;]*[A-Z0-9+&@#/%=~_|$]",
                        Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
        Matcher regexMatcher = regex.matcher(url);
        foundMatch = regexMatcher.matches();
        return foundMatch;
    } catch (PatternSyntaxException ex) {
        // Syntax error in the regular expression
        return false;
    }
}

public static boolean atLeastOneChr(String string) {
    if (string == null)
        return false;

    boolean foundMatch = false;
    try {
        Pattern regex = Pattern.compile("[a-zA-Z0-9]",
                Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE);
        Matcher regexMatcher = regex.matcher(string);
        foundMatch = regexMatcher.matches();
        return foundMatch;
    } catch (PatternSyntaxException ex) {
        // Syntax error in the regular expression
        return false;
    }
}

public static boolean isValidEmail(String email, Context context) {
    String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
    CharSequence inputStr = email;
    Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher(inputStr);
    if (matcher.matches()) {
        return true;
    } else {
        // Helper.toast(context, "Email is not valid..!");

        return false;
    }
}

public static boolean isValidUserName(String email, Context context) {
    String expression = "^[0-9a-zA-Z]+$";
    CharSequence inputStr = email;
    Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher(inputStr);
    if (matcher.matches()) {
        return true;
    } else {
        Helper.toast(context, "Username is not valid..!");
        return false;
    }
}

}

最后一件事是确保您在“AndroidManifest”课程中拥有适当的权限。

答案 2 :(得分：0)

什么是PREFS_KEY？看起来像是一个不变的密钥。

所以基本上你要将SharedPreference写入相同的密钥。作为Hashmap的SharedPreferences每个键只有一个值，因此每次编写它时，只剩下最后一个值。

要解决您的问题，最佳解决方案似乎具有不同的键值对，或者具有字符串的arraylist作为值

public void save (Context context, String text) {

    SharedPreferences settings;
    Editor editor;
    settings = PreferenceManager.getDefaultSharedPreferences(context);
    settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    editor = settings.edit();
    ArrayList<String> notes = getValue(context);
    notes.add(text);
}

然后使用以下链接保存一个arraylist Save ArrayList to SharedPreferences 

public ArrayList<String> getValue(Context context) {

    SharedPreferences settings;
    String text;
    settings = PreferenceManager.getDefaultSharedPreferences(context);
    settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    text = settings.getString(PREFS_KEY, null);
    return text;
}

答案 3 :(得分：0)

在 build.gradle

中添加此depandence 
compile group: 'com.google.code.gson', name: 'gson', version: '2.3.1'

创建 myPraf.java 类

public class myPraf {

    public static void saveObjectToSharedPreference(Context context,  String serializedObjectKey, Object object) {
        SharedPreferences sharedPreferences = mySinglton.getInStance(context);
        SharedPreferences.Editor sharedPreferencesEditor = sharedPreferences.edit();
        final Gson gson = new Gson();
        String serializedObject = gson.toJson(object);
        sharedPreferencesEditor.putString(serializedObjectKey, serializedObject);
        sharedPreferencesEditor.apply();

    }
    public static <GenericClass> GenericClass getSavedObjectFromPreference(Context context, String preferenceKey, Class<GenericClass> classType) {
        SharedPreferences sharedPreferences = mySinglton.getInStance(context);
        if (sharedPreferences.contains(preferenceKey)) {
            final Gson gson = new Gson();
            return gson.fromJson(sharedPreferences.getString(preferenceKey, ""), classType);
        }
        return null;
    }
    public static Set getAllPraf(SharedPreferences prefs)
    {
        Map<String,?> entries = prefs.getAll();
        Set<String> keys = entries.keySet();
        for (String key : keys) {

            Log.d("CustomAdapter",key);

        }
        Log.d("CustomAdapter",""+keys.size());
        return keys;
    }

    public static void deletePraf(Context context  , String mPrafKey)
    {
        SharedPreferences settings = mySinglton.getInStance(context);
        settings.edit().remove(mPrafKey).apply();
    }
    public static int getPrafSize(Context context)
    {
        Map<String,?> entries = mySinglton.getInStance(context).getAll();
        Set<String> keys = entries.keySet();
        return keys.size();
    }
}

并创建您的Singlton或复制此代码 mySinglton.java 

public class mySinglton
{
    private static SharedPreferences mySingltonSharePraf;


    private mySinglton() {
    }

    public static SharedPreferences getInStance(Context context)

   {
       if(mySingltonSharePraf==null)
       {

           mySingltonSharePraf = context.getSharedPreferences("mPreference1",0);

       }
       return mySingltonSharePraf;
   }




}

然后当你想保存你的java对象jast 调用这个mathod 

myPraf.getAllPraf(context)) // this will creat the SharedPref if already not created
     myPraf.saveObjectToSharedPreference(Context context,  String serializedObjectKey, Object object)

获取 您的java对象只需调用此mathod` 

myPraf.getSavedObjectFromPreference(Context context, String preferenceKey, Class<GenericClass> classType)`

或获取所有 java objs键

Set myPrafKeysSet =myPraf.getAllPraf(mySinglton.getInStance(context))

答案 4 :(得分：-1)

我认为您应首先获取首选项然后保存。例如：

String textinput = textEtxt.getText().toString();
String text = settings.getString(PREFS_KEY, "");

text = text + textinput;

sharedPreference.save(context, text);
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