淡入淡出效果

  @Override
    public void finish() {
        super.finish();
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ECLAIR) {
            overridePendingTransition(R.anim.fade_in, R.anim.fade_out);//如果没有这句，就失去了淡出的效果
        }
    }

<?xml version="1.0" encoding="utf-8"?>
fade_in :
<!-- 弹出时动画 -->
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromAlpha="0"
    android:toAlpha="1"
    android:duration="200"
    android:fillAfter="true"/>

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

<!-- 弹出时动画 -->
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromAlpha="1"
    android:toAlpha="0"
    android:duration="200"
    android:fillAfter="true"/>