AndroidManifestLines.xml

<application
    android:name=".MyApp"
    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">

MyApp.java

package tr.com.cagrialdemir.splashcreenexample;

import android.app.Application;
import android.os.SystemClock;

public class MyApp extends Application {

    @Override
    public void onCreate() {
        super.onCreate();
        SystemClock.sleep(2500);
    }
}