[Java] 4 steps to implement splash screen on Android

Hello, this is momorito. This time, I will summarize the ** procedure for implementing the splash screen ** when creating an Android application.

Possible ways to implement a splash screen

• Set the style for the splash screen and replace the Theme of Activity (** Theme replacement type **)
• Create an activity for the splash screen and make a transition (** Activity transition type **)

Etc., but this time we will implement it with the former ** Theme replacement type **.

1 Introduction

(1) Completed form

As shown in the gif below, tap the app → display the splash screen → after a few seconds, apply the original theme and aim to display the main activity.

(2) Rough image of splash screen display

1. Create a Theme to display the splash screen and apply it to the Activity at startup (MainActivity this time).
2. Start MainActivity and wait for a few seconds (2 seconds this time) with onCreate.
3. Apply the original Theme to MainActivity.

(3) Prerequisites

• Use Android Studio 4.1.1
• Launch Android Studio and select Empty Activity in Create New project
• Implementation environment is emulator Pixel 3 XL (API 29)
• Language used is Java

2 Mounting procedure

(1) Create a theme (splash.xml) for the splash screen

Prepare the image you want to display

This time I used the image below. It is a png prepared by 160px x 160px. (Other sizes are OK as long as they are displayed.) The file name is splash_logo.png.

Set the background color for the splash screen.

Since the image is displayed in the center of the screen this time, set the background color outside the image. Since the background of the image itself was set with ■ # 6A91ED , the same color is defined in color.xml.

color.xml

…
<color name ="background_color">#6A91ED</color>
…

Create splash.xml

Right-click on the drawable folder → select New → Drawable Resource File to create splash.xml. The name is splash and the root element is layer-lits. Describe as follows in splash.xml.

splash.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:opacity="opaque"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
　　<!--Background color setting-->
    <item
        android:drawable="@color/background_color"/>　

　　<!--Image settings to display-->
    <item>
        <bitmap
            android:gravity="center"
            android:src="@drawable/splash_logo"/>
    </item>

</layer-list>

This completes splash.xml.

(2) Describe the style to which splash.xml is applied.

This time, there is themes.xml in res/values, so I will describe it in it. It seems that styles.xml was created in res/values ​​in the past ... Well, as long as you can describe style, there is no problem. Add as follows to themes.xml. In addition, although the original Theme is set for parent, it may be refreshing to set NoActionBar in some cases.

Themes.xml

　　…
    <style name="SplashTheme" parent="Theme.InfoDevice">
        <item name="android:windowBackground">@drawable/splash</item>
    </style>
　　…

(3) Change Theme when MainActivity starts

Apply Theme for splash screen to AndroidManifest.xml. At this time, please remember the original Theme firmly. (In this example, the theme called Theme_InfoDevice was originally applied.)

Change before

AndroidManifest.xml

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

After change

AndroidManifest.xml

        <activity
            android:name=".MainActivity"
            android:theme="@style/SplashTheme" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

under android: name

android:theme="@style/SplashTheme"

I am adding. (If originally stated, rewrite @ style/... below to Theme for the splash screen.)

(4) Wait a few seconds for MainActivity and return to the original theme

After starting MainActivity, the theme of the splash screen has been applied, so wait a few seconds and then return to the original theme. The contents to be described in MainActivity are as follows.

MainActivity.java

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        setTheme(R.style.Theme_InfoDevice);   //Originally applied theme
        setContentView(R.layout.activity_main);

        …

    }

This completes it.