Shared Preferences in Android

Shared Preferences in Android

Shared Preferences allows activities and applications to keep preferences, in the form of key-value pairs similar to a Map that will persist even when the user closes the application.

Android stores Shared Preferences settings as XML file in shared_prefs folder under DATA/data/{application package} directory. The DATA folder can be obtained by calling Environment.getDataDirectory().

MainActivity.java

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {
 SharedPreferences sharedpreferences;
 TextView name;
 TextView email;
 public static final String mypreference = "mypref";
 public static final String Name = "nameKey";
 public static final String Email = "emailKey";

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 name = (TextView) findViewById(R.id.etName);
 email = (TextView) findViewById(R.id.etEmail);
 sharedpreferences = getSharedPreferences(mypreference,
 Context.MODE_PRIVATE);
 if (sharedpreferences.contains(Name)) {
 name.setText(sharedpreferences.getString(Name, ""));
 }
 if (sharedpreferences.contains(Email)) {
 email.setText(sharedpreferences.getString(Email, ""));

 }

 }

 public void Save(View view) {
 String n = name.getText().toString();
 String e = email.getText().toString();
 SharedPreferences.Editor editor = sharedpreferences.edit();
 editor.putString(Name, n);
 editor.putString(Email, e);
 editor.commit();
 }

 public void clear(View view) {
 name = (TextView) findViewById(R.id.etName);
 email = (TextView) findViewById(R.id.etEmail);
 name.setText("");
 email.setText("");

 }

 public void Get(View view) {
 name = (TextView) findViewById(R.id.etName);
 email = (TextView) findViewById(R.id.etEmail);
 sharedpreferences = getSharedPreferences(mypreference,
 Context.MODE_PRIVATE);

 if (sharedpreferences.contains(Name)) {
 name.setText(sharedpreferences.getString(Name, ""));
 }
 if (sharedpreferences.contains(Email)) {
 email.setText(sharedpreferences.getString(Email, ""));

 }
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
 // Inflate the menu; this adds items to the action bar if it is present.
 getMenuInflater().inflate(R.menu.menu_main, menu);
 return true;
 }

} 





activity_main.xml




<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:paddingBottom="@dimen/activity_vertical_margin"
 android:paddingLeft="@dimen/activity_horizontal_margin"
 android:paddingRight="@dimen/activity_horizontal_margin"
 android:paddingTop="@dimen/activity_vertical_margin" >
 
 <Button
 android:id="@+id/btnSave"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerVertical="true"
 android:layout_alignParentLeft="true"
 android:layout_alignParentStart="true"
 android:onClick="Save"
 android:text="Save" />
 
 <Button
 android:id="@+id/btnRetr"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerHorizontal="true"
 android:layout_centerVertical="true"
 android:onClick="Get"
 android:text="Retrieve" />
 
 <Button
 android:id="@+id/btnClear"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_alignRight="@+id/etEmail"
 android:layout_centerVertical="true"
 android:layout_alignParentRight="true"
 android:layout_alignParentEnd="true"
 android:onClick="clear"
 android:text="Clear" />
 
 <EditText
 android:id="@+id/etEmail"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:ems="10"
 android:hint="Email"
 android:inputType="textEmailAddress"
 android:layout_below="@+id/etName"
 android:layout_marginTop="20dp"
 android:layout_alignParentRight="true"
 android:layout_alignParentEnd="true" />
 
 <EditText
 android:id="@+id/etName"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:ems="10"
 android:hint="Name"
 android:inputType="text"
 android:layout_alignParentTop="true"
 android:layout_alignLeft="@+id/etEmail"
 android:layout_alignStart="@+id/etEmail" />
 
</RelativeLayout>



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