Question

如果我有ID = 5并且我想要保存在SharedPreferences我得到结果5,5这是错误的我使用的代码是

String FavoritsKey = "com.test";
SharedPreferences preferences = getApplicationContext().getSharedPreferences("SpeakEgyptPreferences", Context.MODE_PRIVATE); 
preferences.edit().putString(FavoritsKey,  preferences.getString(FavoritsKey, "")+","+ selected.Id).apply();

例如

我第一次要保存5 =＆gt;应该得到string =＆＃34;，5＆＃34;但我得到＆＃34;，5,5＆＃34;等等

如何解决重复

Answer 1

我已按如下方式解释您的问题：您希望将ID（"5"）保存到共享首选项，当您检索它时，应将其返回为",5"。这意味着您可以在共享首选项中保存"5"并在检索时添加,，或者保存包含逗号（",5"）的ID。

/* Storing the id */
String FavoritsKey = "com.test";
String valueToSave = "" + selected.ID; // we'll store "5" in sharedPreferences
Editor edit = preferences.edit();    
edit.putString(FavoritsKey, valueToSave);
edit.commit(); //almost the same as apply, you can read the API docs if you want

/* Retrieving the id and prefix it */
String valueToRetrieve = preferences.getString(FavoritsKey, ""); // retrieve "5"
valueToRetrieve = "," + valueToRetrieve; // well prefix the "5" with "," for ",5"

或者相反

/* Storing the id with prefixed comma*/
String FavoritsKey = "com.test";
String valueToSave = "," + selected.ID; // we'll store ",5" in sharedPreferences
Editor edit = preferences.edit();    
edit.putString(FavoritsKey, valueToSave);
edit.commit(); //almost the same as apply, you can read the API docs if you want

/* Retrieving the id with a prefixed comma */
String valueToRetrieve = preferences.getString(FavoritsKey, ""); // retrieve ",5"

但是，您的代码完全按照原样执行。

preferences.edit().putString(FavoritsKey,  preferences.getString(FavoritsKey, "")+","+ selected.Id).apply();

让我们仔细看看。在sharedPreferences中，在密钥FavoritsKey上，您可以存储：

preferences.getString(FavoritsKey, "")+","+ selected.Id) 
//lets assume ",5" was stored initially
//outcome is ",5" + "," + 5 => thats ",5,5"
//and the next time another ",5" is added, and so on, etc...

SharedPreferences重复保存的数据

1 个答案: