Using Kotlin, the values of SharedPreferences can be set and retrieved.<\/h2>\n
We have the ability to assign values to our SharedPreference instance using Kotlin by following this approach.<\/p>\n
val sharedPreference = getSharedPreferences(\"PREFERENCE_NAME\",Context.MODE_PRIVATE)\r\nvar editor = sharedPreference.edit()\r\neditor.putString(\"username\",\"Anupam\")\r\neditor.putLong(\"l\",100L)\r\neditor.commit()\r\n<\/code><\/pre>\nWhen it comes to obtaining a value:<\/p>\n
sharedPreference.getString(\"username\",\"defaultName\")\r\nsharedPreference.getLong(\"l\",1L)\r\n<\/code><\/pre>\n![\"android](\"https:\/\/cdn.silicloud.com\/blog-img\/blog\/img\/655dd4f1cdcf9b6757a01a5e\/11-0.png\" "\\"\\"")
<\/div>\nOne option for paraphrasing the given sentence natively could be:<\/h2>\n
Kotlin code that can be used to clear and delete the stored records in SharedPreferences.<\/p>\n
By using the clear() and remove(String key) methods, we have the option to either remove a specific value or clear all the values.<\/p>\n
editor.clear()\r\neditor.remove(\"username\")\r\n<\/code><\/pre>\nThe modifications made to the editor after the commit or apply are not taken into account. The method described above for saving and retrieving values from a SharedPreference is very similar to what we do in Java. So, where does Kotlin offer its unique benefits? We will explore this by looking at an example Android application.<\/p>\n
The project structure of an Android Kotlin project that utilizes SharedPreferences.<\/h2>\n![\"android](\"https:\/\/cdn.silicloud.com\/blog-img\/blog\/img\/655dd4f1cdcf9b6757a01a5e\/17-0.png\" "\\"\\"")
<\/div>\n1. Code for the design structure.<\/h3>\n
Here is the code for the activity_main.xml layout file.<\/p>\n
<?xml version=\"1.0\" encoding=\"utf-8\"?>\r\n<RelativeLayout xmlns:android=\"http:\/\/schemas.android.com\/apk\/res\/android\"\r\n android:layout_width=\"match_parent\"\r\n android:layout_height=\"match_parent\"\r\n android:orientation=\"vertical\">\r\n\r\n <EditText\r\n android:id=\"@+id\/inUserId\"\r\n android:layout_width=\"match_parent\"\r\n android:layout_height=\"wrap_content\"\r\n android:layout_alignParentTop=\"true\"\r\n android:hint=\"User ID\"\r\n android:inputType=\"number\" \/>\r\n\r\n <EditText\r\n android:id=\"@+id\/inPassword\"\r\n android:layout_width=\"match_parent\"\r\n android:layout_height=\"wrap_content\"\r\n android:layout_below=\"@+id\/inUserId\"\r\n android:hint=\"Password\"\r\n android:inputType=\"textPassword\" \/>\r\n\r\n <Button\r\n android:id=\"@+id\/btnSave\"\r\n android:layout_width=\"wrap_content\"\r\n android:layout_height=\"wrap_content\"\r\n android:layout_below=\"@+id\/inPassword\"\r\n android:text=\"SAVE USER DATA\" \/>\r\n\r\n <Button\r\n android:id=\"@+id\/btnClear\"\r\n android:layout_width=\"wrap_content\"\r\n android:layout_height=\"wrap_content\"\r\n android:layout_alignParentLeft=\"true\"\r\n android:layout_alignParentStart=\"true\"\r\n android:layout_below=\"@+id\/btnSave\"\r\n android:text=\"CLEAR USER DATA\" \/>\r\n\r\n <Button\r\n android:id=\"@+id\/btnShow\"\r\n android:layout_width=\"wrap_content\"\r\n android:layout_height=\"wrap_content\"\r\n android:layout_alignParentRight=\"true\"\r\n android:layout_below=\"@+id\/inPassword\"\r\n android:text=\"SHOW\" \/>\r\n\r\n <Button\r\n android:id=\"@+id\/btnShowDefault\"\r\n android:layout_width=\"wrap_content\"\r\n android:layout_height=\"wrap_content\"\r\n android:layout_alignParentEnd=\"true\"\r\n android:layout_alignParentRight=\"true\"\r\n android:layout_below=\"@+id\/btnSave\"\r\n android:text=\"Show Default\" \/>\r\n\r\n\r\n<\/RelativeLayout>\r\n<\/code><\/pre>\nThe Kotlin code for the main activity.<\/h3>\n
Here is the code for the Kotlin class MainActivity.kt.<\/p>\n
package com.scdev.androidlysharedpreferences\r\n\r\nimport android.content.Context\r\nimport android.content.SharedPreferences\r\nimport android.support.v7.app.AppCompatActivity\r\nimport android.os.Bundle\r\nimport android.preference.PreferenceManager\r\nimport android.view.View\r\nimport com.scdev.androidlysharedpreferences.PreferenceHelper.defaultPreference\r\nimport com.scdev.androidlysharedpreferences.PreferenceHelper.password\r\nimport com.scdev.androidlysharedpreferences.PreferenceHelper.userId\r\nimport com.scdev.androidlysharedpreferences.PreferenceHelper.clearValues\r\nimport com.scdev.androidlysharedpreferences.PreferenceHelper.customPreference\r\n\r\nimport kotlinx.android.synthetic.main.activity_main.*\r\n\r\nclass MainActivity : AppCompatActivity(), View.OnClickListener {\r\n\r\n val CUSTOM_PREF_NAME = \"User_data\"\r\n\r\n override fun onCreate(savedInstanceState: Bundle?) {\r\n super.onCreate(savedInstanceState)\r\n setContentView(R.layout.activity_main)\r\n\r\n btnSave.setOnClickListener(this)\r\n btnClear.setOnClickListener(this)\r\n btnShow.setOnClickListener(this)\r\n btnShowDefault.setOnClickListener(this)\r\n\r\n }\r\n\r\n override fun onClick(v: View?) {\r\n val prefs = customPreference(this, CUSTOM_PREF_NAME)\r\n when (v?.id) {\r\n R.id.btnSave -> {\r\n prefs.password = inPassword.text.toString()\r\n prefs.userId = inUserId.text.toString().toInt()\r\n }\r\n R.id.btnClear -> {\r\n prefs.clearValues\r\n\r\n }\r\n R.id.btnShow -> {\r\n inUserId.setText(prefs.userId.toString())\r\n inPassword.setText(prefs.password)\r\n }\r\n R.id.btnShowDefault -> {\r\n\r\n val defaultPrefs = defaultPreference(this)\r\n inUserId.setText(defaultPrefs.userId.toString())\r\n inPassword.setText(defaultPrefs.password)\r\n }\r\n }\r\n }\r\n\r\n\r\n}\r\n\r\nobject PreferenceHelper {\r\n\r\n val USER_ID = \"USER_ID\"\r\n val USER_PASSWORD = \"PASSWORD\"\r\n\r\n fun defaultPreference(context: Context): SharedPreferences = PreferenceManager.getDefaultSharedPreferences(context)\r\n\r\n fun customPreference(context: Context, name: String): SharedPreferences = context.getSharedPreferences(name, Context.MODE_PRIVATE)\r\n\r\n inline fun SharedPreferences.editMe(operation: (SharedPreferences.Editor) -> Unit) {\r\n val editMe = edit()\r\n operation(editMe)\r\n editMe.apply()\r\n }\r\n\r\n var SharedPreferences.userId\r\n get() = getInt(USER_ID, 0)\r\n set(value) {\r\n editMe {\r\n it.putInt(USER_ID, value)\r\n }\r\n }\r\n\r\n var SharedPreferences.password\r\n get() = getString(USER_PASSWORD, \"\")\r\n set(value) {\r\n editMe {\r\n it.putString(USER_PASSWORD, value)\r\n }\r\n }\r\n\r\n var SharedPreferences.clearValues\r\n get() = { }\r\n set(value) {\r\n editMe {\r\n it.clear()\r\n }\r\n }\r\n}\r\n\r\n\r\n<\/code><\/pre>\nWith the help of Kotlin Android Extensions, we can avoid using findViewById for each XML view. In the provided code, we are generating a singleton class using the object keyword. A higher-order function named editMe() is declared as an inline function, which contains the logic for the edit operation. We have defined individual properties for each value. The use of get and set Kotlin properties allows us to fetch and modify the data in the shared preferences. Kotlin has significantly reduced the verbosity of the code, resulting in a cleaner appearance. Moreover, we can enhance its conciseness by utilizing another Kotlin higher-order function demonstrated below.<\/p>\n
fun SharedPreferences.Editor.put(pair: Pair<String, Any>) {\r\n val key = pair.first\r\n val value = pair.second\r\n when(value) {\r\n is String -> putString(key, value)\r\n is Int -> putInt(key, value)\r\n is Boolean -> putBoolean(key, value)\r\n is Long -> putLong(key, value)\r\n is Float -> putFloat(key, value)\r\n else -> error(\"Only primitive types can be stored in SharedPreferences\")\r\n }\r\n<\/code><\/pre>\nAnd while assigning the values, we carry out the following actions.<\/p>\n
var SharedPreferences.password\r\n get() = getString(USER_PASSWORD, \"\")\r\n set(value) {\r\n editMe {\r\n it.put(USER_PASSWORD to value)\r\n }\r\n }\r\n<\/code><\/pre>\n![\"android](\"https:\/\/cdn.silicloud.com\/blog-img\/blog\/img\/655dd4f1cdcf9b6757a01a5e\/28-0.gif\" "\\"\\"")
<\/div>\nYou are able to obtain the source code by clicking on the provided link: AndroidlySharedPreferences.<\/p>\n
<\/p>\n
More tutorials<\/p>\n
A class in Kotlin that is sealed.(Opens in a new browser tab)<\/span><\/a><\/p>\nHow can you determine the standard deviation in R?(Opens in a new browser tab)<\/span><\/a><\/p>\nget pandas DataFrame from an API endpoint that lacks order?(Opens in a new browser tab)<\/span><\/a><\/p>\nJSON fundamentals(Opens in a new browser tab)<\/span><\/a><\/p>\n