package com.loaderman.daynightdemo;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.support.v7.app.AppCompatDelegate;

import android.support.v7.widget.Toolbar;

import android.view.View;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    {

        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_AUTO);

    }

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

        setSupportActionBar(toolbar);

        findViewById(R.id.btn_auto).setOnClickListener(this);

        findViewById(R.id.btn_day).setOnClickListener(this);

        findViewById(R.id.btn_night).setOnClickListener(this);

        findViewById(R.id.fab).setOnClickListener(this);

    }

    @Override

    public void onClick(View v) {

        switch (v.getId()) {

            case R.id.btn_auto: {

                getDelegate().setLocalNightMode(AppCompatDelegate.MODE_NIGHT_AUTO);

                recreate();

                break;

            }

            case R.id.btn_day: {

                getDelegate().setLocalNightMode(AppCompatDelegate.MODE_NIGHT_NO);

                recreate();

                break;

            }

            case R.id.btn_night: {

                getDelegate().setLocalNightMode(AppCompatDelegate.MODE_NIGHT_YES);

                recreate();

                break;

            }

        }

    }

}

<?xml version="1.0" encoding="utf-8"?>

<android.support.design.widget.CoordinatorLayout

    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"

    android:fitsSystemWindows="true"

    tools:context="com.yanzhenjie.daynight.MainActivity">

    <android.support.design.widget.AppBarLayout

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar

            android:id="@+id/toolbar"

            android:layout_width="match_parent"

            android:layout_height="?attr/actionBarSize"

            android:background="?attr/colorPrimary"

            app:popupTheme="@style/AppTheme.PopupOverlay"/>

    </android.support.design.widget.AppBarLayout>

    <include layout="@layout/content_main"/>

    <android.support.design.widget.FloatingActionButton

        android:id="@+id/fab"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_gravity="bottom|end"

        android:layout_margin="@dimen/fab_margin"

        android:src="@android:drawable/ic_dialog_email"/>

</android.support.design.widget.CoordinatorLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout 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"

    android:orientation="vertical"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    app:layout_behavior="@string/appbar_scrolling_view_behavior"

    tools:context="com.yanzhenjie.daynight.MainActivity"

    tools:showIn="@layout/activity_main">

    <Button

        android:id="@+id/btn_auto"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="自动模式" />

    <Button

        android:id="@+id/btn_day"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="日间模式" />

    <Button

        android:id="@+id/btn_night"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="夜间模式" />

</LinearLayout>

<resources>

    <style name="AppTheme" parent="Theme.AppCompat.DayNight.DarkActionBar">

        <item name="colorPrimary">@color/colorPrimary</item>

        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>

        <item name="colorAccent">@color/colorAccent</item>

    </style>

    <style name="AppTheme.NoActionBar">

        <item name="windowActionBar">false</item>

        <item name="windowNoTitle">true</item>

    </style>

    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

</resources>

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.loaderman.daynightdemo">

    <application

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:supportsRtl="true"

        android:theme="@style/AppTheme">

        <activity

            android:name=".MainActivity"

            android:label="@string/app_name"

            android:theme="@style/AppTheme.NoActionBar">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>