Activity reloads when orientation changes in Android

Question

When my main activity starts after the splash screen it parses 4 big XML files. This takes a few seconds and I'm able to hide this in the time the splash screen shows at startup.

But when the screen orientation changes or when I go back to the main activity after a sub-activity it parses again and thus fore my app 'hangs' for a few seconds and it doesn't respond or anything in that time.

I understand this is normal behaviour in Android, but isn't there a way to avoid this?

I read something about savedinstancestate, but I can't seem to understand the docs..

Answer 1

add this code in your android manifest file in every activity node if you're targeting API level 12 or less.

android:configChanges="orientation|keyboardHidden"

For level 13 and onwards you also have to include "screensize", ie:

    android:configChanges="orientation|keyboardHidden|screenSize"

now paste this code in your every activity's java classes.

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);

    // Checks the orientation of the screen
    if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
    } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){
        Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
    }
    // Checks whether a hardware keyboard is available
    if (newConfig.hardKeyboardHidden == Configuration.HARDKEYBOARDHIDDEN_NO) {
        Toast.makeText(this, "keyboard visible", Toast.LENGTH_SHORT).show();
    } else if (newConfig.hardKeyboardHidden == Configuration.HARDKEYBOARDHIDDEN_YES) {
        Toast.makeText(this, "keyboard hidden", Toast.LENGTH_SHORT).show();
    }
}

Answer 2

您可以通过在AndroidManifest文件中为您的活动添加android：configChanges =“orientation”来防止这种情况。