Android5.0以上startActivity系统自带动画效果,如果需要去掉自带效果有两种方法,

第一种就是在startActivity的时候加上

Intent intent = new Intent(mContext, MainActivity2.class);
mContext.startActivity(intent);
((Activity) mContext).overridePendingTransition(0, 0);
((Activity) mContext).overridePendingTransition(0, 0);

第二种方法就是

在styles.xml文件修改

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
   <item name="android:windowAnimationStyle">@style/Animation</item>
</style>

<style name="Animation">
    <item name="android:activityOpenEnterAnimation">@null</item>
    <item name="android:activityOpenExitAnimation">@null</item>
    <item name="android:activityCloseEnterAnimation">@null</item>
    <item name="android:activityCloseExitAnimation">@null</item>
    <item name="android:taskOpenEnterAnimation">@null</item>
    <item name="android:taskOpenExitAnimation">@null</item>
    <item name="android:taskCloseEnterAnimation">@null</item>
    <item name="android:taskCloseExitAnimation">@null</item>
    <item name="android:taskToFrontEnterAnimation">@null</item>
    <item name="android:taskToFrontExitAnimation">@null</item>
    <item name="android:taskToBackEnterAnimation">@null</item>
    <item name="android:taskToBackExitAnimation">@null</item>
</style>

加上 <item name="android:windowAnimationStyle">@style/Animation</item>的样式,就会去掉自带效果