SharedPreferences in Android Studio

 

How to Use SharedPreferences in Android Studio (With Example)

In Android development, SharedPreferences is used to store small amounts of data as key-value pairs, such as user preferences or simple settings. This data is stored persistently across app launches and remains until explicitly removed.

activity_shared_preference.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#F0F4F8"
    android:gravity="center"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="15dp"
        android:background="#212121"
        android:gravity="center"
        android:text="Shared Preference Demo"
        android:textColor="#FEFEFE"
        android:textSize="30sp" />

    <EditText
        android:id="@+id/nameEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/rounded_edittext"
        android:hint="Enter your name"
        android:textSize="35sp" />

    <Button
        android:id="@+id/saveBtn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:background="@drawable/rounded_button"
        android:text="Save Name"
        android:textSize="35sp" />

    <Button
        android:id="@+id/showBtn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:background="@drawable/rounded_button"
        android:text="Show Saved Name"
        android:textSize="35sp" />

    <TextView
        android:id="@+id/savedName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:gravity="center"
        android:background="@drawable/rounded_result"
        android:text="Show Saved Name"
        android:textSize="35sp" />
</LinearLayout>

SharedPreferenceActivity.java

package com.vipul.p6;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class SharedPreferenceActivity extends AppCompatActivity {

    EditText nameEditText;
    Button saveBtn, showBtn;
    TextView savedNames;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_shared_preference);

        nameEditText = findViewById(R.id.nameEditText);
        saveBtn = findViewById(R.id.saveBtn);
        showBtn = findViewById(R.id.showBtn);
        savedNames = findViewById(R.id.savedName);

        saveBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = nameEditText.getText().toString();
                SharedPreferences sharedPreferences = getSharedPreferences("MyPrefs", MODE_PRIVATE);
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putString("username", name);
                editor.apply();
                Toast.makeText(getApplicationContext(), "Name saved!", Toast.LENGTH_SHORT).show();
                savedNames.setText(name);
            }
        });

        showBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SharedPreferences sharedPreferences = getSharedPreferences("MyPrefs", MODE_PRIVATE);
                String savedName = sharedPreferences.getString("username", "No name saved");
                Toast.makeText(getApplicationContext(), "Saved Name: " + savedName, Toast.LENGTH_SHORT).show();
                savedNames.setText(savedName);
            }
        });
    }
}

Detailed Explanation of the Code:

XML Layout:

• TextView shows the app heading.
• EditText is where the user can input their name.
• Save Name Button saves the input into SharedPreferences.
• Show Saved Name Button retrieves and displays the saved name.
• savedName TextView displays the current stored name.

Java Code:

• When the Save button is clicked, it stores the name using SharedPreferences.Editor and displays a Toast confirmation.
• When the Show button is clicked, it retrieves the name from SharedPreferences and displays it both as a Toast and in the TextView.

What is SharedPreferences in Android?

SharedPreferences is a lightweight way to store key-value data in Android. It is perfect for saving simple data like user settings, login info, or preferences that persist even after the app is closed.

Key Features of SharedPreferences:

• Stores data persistently (even after the app is closed).
• Data is stored in XML format in the app’s private directory.
• Only suitable for small key-value data storage.
• Can be easily accessed and modified.

How to use SharedPreferences:

1. Create or access SharedPreferences using getSharedPreferences("YourPrefName", MODE_PRIVATE).
2. Use Editor to save data using putString(), putInt(), etc.
3. Apply or commit changes using editor.apply().
4. Retrieve data using getString(), getInt(), etc.

Conclusion:

SharedPreferences is an essential tool for Android developers to store small bits of data persistently. This example provides a very simple and practical demonstration for beginners to understand and implement SharedPreferences in their own projects.