Android – Implement Night Mode using Switch

Night Mode (also known as Black Mode or Dark Mode) is a screen display that uses dark background. Opposite to Light Mode which uses light background and dark text, night mode uses a dark background and light text. Dark mode reduces battery consumption, this is because the device finds it easier to run the dark background as it does not have to light the entire screen. In this article, we will build a simple app to implement night mode using Switch in android.

Step-by-Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Java as the programming language.

Step 2: Working with the activity_main.xml file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <!--implementing switch -->
    <com.google.android.material.switchmaterial.SwitchMaterial
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/switchBtn"
        app:layout_constraintWidth_percent="0.8"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

Step 3: Working with the MainActivity.java file

Go to the MainActivity.java file and refer to the following code. Below is the code for the MainActivity.java file. Comments are added inside the code to understand the code in more detail.

Java

package com.example.nightmodebutton;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.app.AppCompatDelegate;
import android.os.Bundle;
import android.widget.CompoundButton;
import com.google.android.material.switchmaterial.SwitchMaterial;
import java.util.Objects;

public class MainActivity extends AppCompatActivity {

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

        // initialize variable
        SwitchMaterial switchBtn = findViewById(R.id.switchBtn);

        Objects.requireNonNull(getSupportActionBar ()).setTitle("LIGHT-NIGHT MODE SWITCH");

        // switch theme mode per user wishes
        // setting onCheckedListener on switch
        switchBtn.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged (CompoundButton buttonView, boolean isChecked){

                // checking if the switch is turned on
                if (isChecked) {

                    // setting theme to night mode
                    AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
                    buttonView.setText("Night Mode");
                }

                // if the above condition turns false
                // it means switch is turned off
                // by-default the switch will be off
                else {

                    // setting theme to light theme
                    AppCompatDelegate.setDefaultNightMode (AppCompatDelegate.MODE_NIGHT_NO);
                    buttonView.setText("Light Mode");
                }
            }
        });
    }
}

Output: