我想存储一个时间值,需要检索和编辑它。我如何使用SharedPreferences来做到这一点?
当前回答
Edit
SharedPreferences pref = getSharedPreferences("YourPref", MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putString("yourValue", value);
editor.commit();
Read
SharedPreferences pref = getSharedPreferences("YourPref", MODE_PRIVATE);
value= pref.getString("yourValue", "");
其他回答
SharedPreferences的基本思想是将内容存储在XML文件中。
Declare your xml file path.(if you don't have this file, Android will create it. If you have this file, Android will access it.) SharedPreferences prefs = this.getSharedPreferences("com.example.app", Context.MODE_PRIVATE); Write value to Shared Preferences prefs.edit().putLong("preference_file_key", 1010101).apply(); the preference_file_key is the name of shared preference files. And the 1010101 is the value you need to store. apply() at last is to save the changes. If you get error from apply(), change it to commit(). So this alternative sentence is prefs.edit().putLong("preference_file_key", 1010101).commit(); Read from Shared Preferences SharedPreferences sp = this.getSharedPreferences("com.example.app", Context.MODE_PRIVATE); long lsp = sp.getLong("preference_file_key", -1); lsp will be -1 if preference_file_key has no value. If 'preference_file_key' has a value, it will return the value of this.
整个代码是
SharedPreferences prefs = this.getSharedPreferences("com.example.app", Context.MODE_PRIVATE); // Declare xml file
prefs.edit().putLong("preference_file_key", 1010101).apply(); // Write the value to key.
阅读的代码是
SharedPreferences sf = this.getSharedPreferences("com.example.app", Context.MODE_PRIVATE); // Declare xml file
long lsp = sp.getLong("preference_file_key", -1); // Read the key and store in lsp
我想在这里补充一点,当使用SharedPreferences时,这个问题的大多数代码片段都有类似MODE_PRIVATE的东西。MODE_PRIVATE意味着无论您写入这个共享首选项的是什么,都只能由您的应用程序读取。
Whatever key you pass to getSharedPreferences() method, android creates a file with that name and stores the preference data into it. Also remember that getSharedPreferences() is supposed to be used when you intend to have multiple preference files for your application. If you intend to use single preference file and store all key-value pairs into it then use the getSharedPreference() method. Its weird why everyone (including myself) simply uses getSharedPreferences() flavor without even understanding the difference between the above two.
下面的视频教程应该会有所帮助 https://www.youtube.com/watch?v=2PcAQ1NBy98
使用这个简单的库,下面是如何调用SharedPreferences..
TinyDB tinydb = new TinyDB(context);
tinydb.putInt("clickCount", 2);
tinydb.putString("userName", "john");
tinydb.putBoolean("isUserMale", true);
tinydb.putList("MyUsers", mUsersArray);
tinydb.putImagePNG("DropBox/WorkImages", "MeAtlunch.png", lunchBitmap);
//These plus the corresponding get methods are all Included
2.用于存储在共享优先级
SharedPreferences.Editor editor =
getSharedPreferences("DeviceToken",MODE_PRIVATE).edit();
editor.putString("DeviceTokenkey","ABABABABABABABB12345");
editor.apply();
2.用于检索相同的用途
SharedPreferences prefs = getSharedPreferences("DeviceToken",
MODE_PRIVATE);
String deviceToken = prefs.getString("DeviceTokenkey", null);
如果你正在与团队中的其他开发人员一起开发一个大型应用程序,并打算让所有内容都很好地组织起来,而不是分散的代码或不同的SharedPreferences实例,你可以这样做:
//SharedPreferences manager class
public class SharedPrefs {
//SharedPreferences file name
private static String SHARED_PREFS_FILE_NAME = "my_app_shared_prefs";
//here you can centralize all your shared prefs keys
public static String KEY_MY_SHARED_BOOLEAN = "my_shared_boolean";
public static String KEY_MY_SHARED_FOO = "my_shared_foo";
//get the SharedPreferences object instance
//create SharedPreferences file if not present
private static SharedPreferences getPrefs(Context context) {
return context.getSharedPreferences(SHARED_PREFS_FILE_NAME, Context.MODE_PRIVATE);
}
//Save Booleans
public static void savePref(Context context, String key, boolean value) {
getPrefs(context).edit().putBoolean(key, value).commit();
}
//Get Booleans
public static boolean getBoolean(Context context, String key) {
return getPrefs(context).getBoolean(key, false);
}
//Get Booleans if not found return a predefined default value
public static boolean getBoolean(Context context, String key, boolean defaultValue) {
return getPrefs(context).getBoolean(key, defaultValue);
}
//Strings
public static void save(Context context, String key, String value) {
getPrefs(context).edit().putString(key, value).commit();
}
public static String getString(Context context, String key) {
return getPrefs(context).getString(key, "");
}
public static String getString(Context context, String key, String defaultValue) {
return getPrefs(context).getString(key, defaultValue);
}
//Integers
public static void save(Context context, String key, int value) {
getPrefs(context).edit().putInt(key, value).commit();
}
public static int getInt(Context context, String key) {
return getPrefs(context).getInt(key, 0);
}
public static int getInt(Context context, String key, int defaultValue) {
return getPrefs(context).getInt(key, defaultValue);
}
//Floats
public static void save(Context context, String key, float value) {
getPrefs(context).edit().putFloat(key, value).commit();
}
public static float getFloat(Context context, String key) {
return getPrefs(context).getFloat(key, 0);
}
public static float getFloat(Context context, String key, float defaultValue) {
return getPrefs(context).getFloat(key, defaultValue);
}
//Longs
public static void save(Context context, String key, long value) {
getPrefs(context).edit().putLong(key, value).commit();
}
public static long getLong(Context context, String key) {
return getPrefs(context).getLong(key, 0);
}
public static long getLong(Context context, String key, long defaultValue) {
return getPrefs(context).getLong(key, defaultValue);
}
//StringSets
public static void save(Context context, String key, Set<String> value) {
getPrefs(context).edit().putStringSet(key, value).commit();
}
public static Set<String> getStringSet(Context context, String key) {
return getPrefs(context).getStringSet(key, null);
}
public static Set<String> getStringSet(Context context, String key, Set<String> defaultValue) {
return getPrefs(context).getStringSet(key, defaultValue);
}
}
在您的活动中,您可以这样保存SharedPreferences
//saving a boolean into prefs
SharedPrefs.savePref(this, SharedPrefs.KEY_MY_SHARED_BOOLEAN, booleanVar);
你可以这样检索你的SharedPreferences
//getting a boolean from prefs
booleanVar = SharedPrefs.getBoolean(this, SharedPrefs.KEY_MY_SHARED_BOOLEAN);
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