Switching between webview fragments

Issue

I have 3 fragments listed in the nav drawer all of which include a webview. By clicking items from the nav drawer, I want to switch between the fragments but also saving their states at the same time. Given code is the listener method for the nav drawer. How do I check if there are any existing instances of the fragment before instantiating a new one?

private void selectItem(int position) {
    Fragment newFragment = new Fragment_1();
    android.support.v4.app.FragmentManager fm = getSupportFragmentManager();
    switch(position) {
        case 0:
            newFragment = new Fragment_1();
            break;
        case 1:
            newFragment = new Fragment_2();
            break;
        case 2:

            break;
    }
    android.support.v4.app.FragmentTransaction t = getSupportFragmentManager().beginTransaction();
    t.replace(R.id.content_frame, newFragment);
    t.addToBackStack(null);
    t.commit();
}

Solution

Well, you have to do it in 2 steps :

1/ Firstly, FragmentTransaction's replace method is not what you need in this case. You will have to switch to

t.add(R.id.content_frame, newFragment, TAG)

With TAG being the tag (a string) of your fragment. In your example you are dealing with 2 fragments so you should define :

private final String TAG_FRAGMENT1 = "fragment1";
private final String TAG_FRAGMENT2 = "fragment2";

And depending of the fragment you want to add, you will call either :

t.add(R.id.content_frame, newFragment, TAG_FRAGMENT1);

OR

t.add(R.id.content_frame, newFragment, TAG_FRAGMENT2);

Followed by :

t.commit();

2/ Now that you will have fragments with TAGs, you will be able to find the existing instance of framgnent1 in the fragment backtrack with :

getSupportFragmentManager().findFragmentByTag(TAG_FRAGMENT1);

This will return the instance of fragment1 if it exists or "null" and in this case, you will have to create a new instance and "add" it with a fragmentTransaction (with what I explained in 1/)

3/ If the findFragmentByTag is returning a fragment (and not null) then you should use the replace method :

FragmentManager fm = getSupportFragmentManager();
Fragment f = fm.findFragmentByTag(TAG_FRAGMENT1);
FragmentTransaction ft = fm.beginTransaction();
ft.replace(R.id.content_frame, f);
ft.commit();

Answered By - poulpi