How to use Shared Preferences to make a simple App in Android (updated with androidx)

The simplest way to store data in an app would be only Shared Preferences.

We are going to make an a small and simple app which store data and no need to use any button to save it. Once you close the scree, whatever you have edited, remains as it is.

----------------------------------------- shared_preferences_activity.xml -----------------------------------------

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="#F57F17"
    android:gravity="center|top">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:weightSum="8"
        android:orientation="vertical">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center"
            android:textSize="20sp"
            android:textStyle="bold"
            android:textColor="#E91E63"
            android:background="#FFB300"
            android:text="Five Goals for this Year"/>

        <EditText
            android:id="@+id/spa_goal1ET"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center"
            android:textStyle="bold"
            android:textColor="#ffffff"
            android:textSize="20sp"/>

        <EditText
            android:id="@+id/spa_goal2ET"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center"
            android:textStyle="bold"
            android:textColor="#ffffff"
            android:textSize="20sp"/>

        <EditText
            android:id="@+id/spa_goal3ET"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:textStyle="bold"
            android:textColor="#ffffff"
            android:gravity="center"
            android:textSize="20sp"/>

        <EditText
            android:id="@+id/spa_goal4ET"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center"
            android:textStyle="bold"
            android:textColor="#ffffff"
            android:textSize="20sp"/>

        <EditText
            android:id="@+id/spa_goal5ET"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center"            android:textStyle="bold"
            android:textColor="#ffffff"
            android:textSize="20sp"/>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:background="#FFB300"
            android:orientation="horizontal">

            <TextView
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:layout_weight="1.5"
                android:gravity="center"
                android:textSize="20sp"
                android:textStyle="bold"
                android:textColor="#E91E63"
                android:text="Progress in %"/>

            <EditText
                android:id="@+id/spa_progressET"
                android:layout_width="0dp"
                android:layout_height="match_parent"
                android:layout_weight="0.5"
                android:gravity="center"
                android:textSize="20sp"
                android:textColor="#ffffff"
                android:text="0%"/>

        </LinearLayout>
    </LinearLayout>
</LinearLayout>

---------------------------------------------------------------

--------------------------------------- SharedPreferencesActivity.java ------------------------------------------

package com.app.yourappname;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.widget.EditText;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

public class SharedPreferencesActivity extends AppCompatActivity {

    private GameDB gdb;
    private EditText goal1ET, goal2ET, goal3ET, goal4ET, goal5ET, progressET;

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

        gdb = new GameDB();

        goal1ET = findViewById(R.id.spa_goal1ET);
        goal2ET = findViewById(R.id.spa_goal2ET);
        goal3ET = findViewById(R.id.spa_goal3ET);
        goal4ET = findViewById(R.id.spa_goal4ET);
        goal5ET = findViewById(R.id.spa_goal5ET);
        progressET = findViewById(R.id.spa_progressET);

        goal1ET.setText(gdb.getString("goal1"));
        goal2ET.setText(gdb.getString("goal2"));
        goal3ET.setText(gdb.getString("goal3"));
        goal4ET.setText(gdb.getString("goal4"));
        goal5ET.setText(gdb.getString("goal5"));
        progressET.setText(""+gdb.getFloat("progress"));
    }

    public class GameDB {
        private static final String PREF_NAME = "DATA";

        public void setString(String key, String value) {
            SharedPreferences.Editor editor = getSharedPreferences(PREF_NAME, MODE_PRIVATE).edit();
            editor.putString(key, value);
            editor.apply();
        }

        public String getString(String key) {
            SharedPreferences prefs = getSharedPreferences(PREF_NAME, MODE_PRIVATE);
            return prefs.getString(key,"");
        }

        public void setFloat(String key, float value) {
            SharedPreferences.Editor editor = getSharedPreferences(PREF_NAME, MODE_PRIVATE).edit();
            editor.putFloat(key, value);
            editor.apply();
        }

        public float getFloat(String key) {
            SharedPreferences prefs = getSharedPreferences(PREF_NAME, MODE_PRIVATE);
            return prefs.getFloat(key,0.0f);
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        gdb.setString("goal1", goal1ET.getText().toString());
        gdb.setString("goal2", goal2ET.getText().toString());
        gdb.setString("goal3", goal3ET.getText().toString());
        gdb.setString("goal4", goal4ET.getText().toString());
        gdb.setString("goal5", goal5ET.getText().toString());
        gdb.setFloat("progress", Float.parseFloat(progressET.getText().toString()));
    }
}

---------------------------------------------------------------

------------------------------------------ Declare Activity name in Manifest file ---------------------------------

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.app.yourappname">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".SharedPreferencesActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

---------------------------------------------------------------