CODEWITHSUNDEEP
javaandroidandroid-fragments
Alphasis
Alphasis

Reputation: 75

How to understand a fragment?

So I have re-write it. The problems are:

  1. If a fragment is declared in xml, then you can't call replace on it. Why?

  2. If you want to put a fragment into a FrameLayout(id, frame_layout), then call add(R.id.frame_layout, fragment) will result in "No View exist Error". There is a way around this by calling add(android.R.id.content, fragment). The problem is, what if the R.id.frame_layout isn't the base layout for your activity?

  3. Also, in dynamic fragment dispatch(using replace and add), maybe only one container could contain one fragment rather than two?

Upvotes: 4

Views: 86

Answers (1)

Alphasis
Alphasis

Reputation: 75

I have browsed a lot...

Q1. If a fragment is declared in xml, then you can't call replace on it. Why?

Because that's a static fragment. Android system would always stick to it. There is no way to remove or replace it. Any new fragment that's "add" or "replace" on the same id would be placed on top of each other.

Q2 If you want to put a fragment into a FrameLayout(id, frame_layout), then call add(R.id.frame_layout, fragment) will result in "No View exist Error". There is a way around this by calling add(android.R.id.content, fragment). The problem is, what if the R.id.frame_layout isn't the base layout for your activity?

This is not true. Depending on situations. Generally speaking, the id in the function call "add(id)" only means the container of the fragment or the view which is to be replaced by fragment. android.R.id.content represents the buttom layer of the views in the activity.

Also, in dynamic fragment dispatch(using replace and add), maybe only one container could contain one fragment rather than two?

Well, it depends. Just for the sake of clarity(if you want co-workers to understand your code), it's good habbit to make sure that only one container contains one fragment. That's dynamic fragment, not the rule of static fragment.

Upvotes: 1

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