at the moment I'm calling and building fragments like this:
if (getSupportFragmentManager().findFragmentById(R.id.fragment_list) == null) {
list = new MyListFragment();
getSupportFragmentManager().beginTransaction().add(R.id.fragment_list, list).commit();
}
But I wonder if this is so called best practice, because this seems to me to be much boilerplate code. Are there better ways?
Use XML layouts and Fragment classes. Here I create a layout with 2 fragments. The class inflates the layout fragment_actionbarcompat.xml (that code isn't shown here but it's a basic layout file). And I create a layout file for the activity that houses the 2 fragments.
The ActionBarCompatFragment class overrides the onCreateView method to inflate it's layout. That gets injected into the fragment tag layoutwise.
In your case normally you don't just add in a plain ListFragment, you extend ListFragment and add your custom code into it. It's a way of better supporting fancy patterns like Model-View-Controller. Fragments are meant to be isolated compartments so you can reuse them between activities if you'd like. In most cases your class will hold the logic to load the data that the fragment needs.
ActionBarCompatFragment.java
#Override
public final View onCreateView(LayoutInflater inflater, ViewGroup root, Bundle savedInstanceState) {
final int layoutId = R.layout.fragment_actionbarcompat;
return inflater.inflate(layoutId, root, false);
}
File: activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<fragment
android:id="#+id/ActionBarCompatFragment"
android:layout_width="#dimen/ActionBarSize"
android:layout_height="match_parent"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
class="com.packagename.app.ActionBarCompatFragment" >
<!-- Preview: layout=#layout/fragment_actionbarcompat -->
</fragment>
<fragment
android:id="#+id/ComposerFragment"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_toRightOf="#id/ActionBarCompatFragment"
class="com.packagename.app.ComposerFragment" >
<!-- Preview: layout=#layout/fragment_composer -->
</fragment>
</RelativeLayout>
Related
I am using the androidX CardView.
In order to make a recyclerview adapter for the cards I need to inflate the custom card layout I have made.
Unfortunately the xml of the custom card view doesn't appear in R.layout.(xml_name),while i find normally all the other layouts.
This the code inside the adapter class where I need to inflate:
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
View view;
LayoutInflater mInflater = LayoutInflater.from(mContext);
view = mInflater.inflate(R.layout.cardview_item_answer); // not finding this layout
return null;
}
This is the card layout xml (cardview_item_answer.xml) :
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="160dp"
android:layout_height="160dp"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_margin="5dp"
app:cardCornerRadius="4dp"
>
<androidx.appcompat.widget.LinearLayoutCompat
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.appcompat.widget.AppCompatImageView
android:id="#+id/image_card"
android:layout_width="match_parent"
android:layout_height="100dp"
android:scaleType="centerCrop"
android:background="#2d2d2d2d">
</androidx.appcompat.widget.AppCompatImageView>
<androidx.appcompat.widget.AppCompatTextView
android:id="#+id/text_card"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="test"
android:textSize="13sp"
android:textColor="#color/black"
android:layout_gravity="center"
></androidx.appcompat.widget.AppCompatTextView>
</androidx.appcompat.widget.LinearLayoutCompat>
Do you suggest any ideas ?
Thank you very much !
Solved !
If you ever have this problem -> clean project and invalidate Caches/Restart.
If the XML contains any errors, your build will likely fail - this will cause R.layout to yield unexpected results. I am not seeing a closing tag for the CardView in cardview_item_answer.xml
Try adding a closing tag </androidx.cardview.widget.CardView> at the end of cardview_item_answer.xml
For some reasons neither of the solutions above worked for me.
I just had to use the full path to the layout before being able to use it. In my case the item of a spinner
So I did this:
import com.myProject.R.layout.spinner_item
It is never a suggested autocompletion, at least in my case, in model views. It is in the fragments. Can't make sense of that, but it works in view models too.
The Android developer documentation for fragments says this:
"Note: When you add a fragment to an activity layout by defining the
fragment in the layout XML file, you cannot remove the fragment at
runtime. If you plan to swap your fragments in and out during user
interaction, you must add the fragment to the activity when the
activity first starts, as shown in the next lesson."
And partly because of this I got into the habit of always using the fragment manager to add/remove fragments to/from my user interface (even if I did not want to "hot swap" them at runtime). I am 100% certain that when I tried to remove/replace "hard wired" XML fragments at runtime my app crashed with an exception.
I haven't really worked with XML fragments for months, but today, on a lark, I decided to play around and I find that I am able to swap XML fragments for other fragments and...it works? I can't find anything online that discusses a recent change in this behavior. It just works.
My layout code is here:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/fl_frag"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context="mobappdev.demo.myapplication.MainActivity">
<fragment
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:id="#+id/frag"
android:name="mobappdev.demo.myapplication.BlankFragment"/>
<Button
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:text="#string/click_me"
android:onClick="clickMe"/>
</LinearLayout>
And here is the code that replaces the fragment:
public void clickMe(View view) {
FragmentManager manager = getSupportFragmentManager();
BlankFragment newFrag = BlankFragment.newInstance();
Fragment oldFrag = manager.findFragmentById(R.id.frag);
Log.i("TESTING", "old frag is null: " + (oldFrag == null));
manager.beginTransaction()
.replace(R.id.fl_frag, newFrag)
.commit();
}
It works without any problems. I've tried variations (putting the XML fragment in a FrameLayout for example) and it all seems to work just fine. I even tried variations such as remove/add and just remove and it all works without a problem.
So what am I missing?
Instead of replacing the fragment itself, you're adding a new fragment on top of that one. It's just a small issue with IDs, but you're replacing using the FragmentManager on the container (LinearLayout) instead of doing it on the fragment itself (R.id.fl_frag instead of R.id.frag)
I'm currently writing an Android app that uses ListView with headers. It works okay, but not really as I want. Every item in ListView has 1-2px separator at the top and bottom of it. So does the header - and that's the problem. It does not look very pretty...
The interesting part is that system apps (like Settings, for instance) does not have such problem.
Here's my example adapter:
setListAdapter(new BaseAdapter() {
#Override
public int getCount() {
return 10;
}
#Override
public Object getItem(int i) {
return i;
}
#Override
public long getItemId(int i) {
return i;
}
#Override
public View getView(int i, View view, ViewGroup viewGroup) {
View v = ((LayoutInflater)getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE))
.inflate(i % 3 == 0 ? R.layout.list_header : android.R.layout.simple_list_item_1, viewGroup, false);
((TextView)v.findViewById(android.R.id.text1)).setText("test");
return v;
}
});
And list header layout file:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#android:id/text1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Hello, World"
style="?android:attr/listSeparatorTextViewStyle">
</TextView>
So the question is: how to get rid of the item separators between headers and regular items, just like, for example, Settings app does?
EDIT:
After reading the answers, I want to clear one thing up. I do not want to remove separators completely. I want to remove them only between the header items and regular items. Also, half-measures like "removing separators completely and adding them on some items" do not satisfy me, too.
It seems that you have to use a custom item view for dividers and a little workaround. Let me explain how to manage this:
Do not use the default dividers, remove it.
Create a custom layout with a View at bottom to be the subline for headers.
Create a custom layout with a View at top to have the divider for items.
Then, the two types of dividers will be glue to make only one subline for header part, so dividers should have the same height in order to make a good subline. This will avoid to have a divider above the header sections but keeping the dividers for items list.
Therefore, let me show some code to achieve it. First, don't forget to avoid default divider on the ListView:
<ListView
android:id="#+id/listview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:divider="#null"
android:dividerHeight="0dp"/>
Create an item layout with a divider at top set to 1dp (or whatever):
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<!-- this is the divider for items -->
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#android:color/darker_gray"/>
<!-- and the rest of item's content in another ViewGroup -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp"
android:orientation="horizontal">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#mipmap/ic_launcher"/>
<TextView
android:id="#+id/item_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="15dp"
android:textColor="#android:color/white"/>
</LinearLayout>
</LinearLayout>
Finally, the header layout with a divider at bottom (with the same height as item's divider):
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/item_header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
style="?android:attr/listSeparatorTextViewStyle"/>
<!-- this is the ("half-")divider for header section -->
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#android:color/darker_gray"/>
<!-- this view above will be merged with item's dividers -->
</LinearLayout>
And it gives this result:
Remove the style you have set for the header TextView
Create your own custom style with required divider and set it to TextView
<style name="CustomListSeperatorTextViewStyle" parent="Widget.TextView.ListSeparator">
<item name="android:background">#drawable/your_own_here</item>
Seperator is due to the style you have set with the textview, just remove the style hope this will work.
I just found these parameters that seem to be what you need, you can try adding them in your ListView:
android:headerDividersEnabled="false"
android:footerDividersEnabled="false"
The documentation is available here and indicates:
When set to false, the ListView will not draw the divider after each header view. The default value is true.
I made a custom view which I called Game.java
public class Game extends View {
public Game(Context context, AttributeSet attrs) {
//here goes class
public void shot(){
}
//method I want to use sometime
}
here's part of my layout file for Activity game.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/root"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".GameActivity" >
<com.vladdrummer.textmaster.Game
android:id="#+id/game"
android:layout_width="wrap_content"
android:windowSoftInputMode="adjustResize"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
<View
android:id="#+id/spareview"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true" />
etc..
So, in Activity I simply do
setContentView(R.layout.game);
and I got my custom View class called Game.java as the part of the screen
But how do I address it? if I do :
Game game;
game =(Game) findViewById(R.id.game);
game.shot();
it crashes.
of course , I can do :
Game game=new Game(this)
setContentView(game);
and have access to game so it won't crash, but I need other elements on screen as well
please tell me how to do it right
You can have a RelativeLayout or LinearLayout in your xml and place it anywhere you want. You can have other views in xml also. This is one way
setContentView(R.layout.yourlayout); // infalte layout
RelativeLayout rl =(RelativeLayout) findViewById(R.id.relativeLayout);// initialize
Game game=new Game(this);
rl.addView(game); // ad view to container
But you have the custom view in your layout. You are missing constructors in GameView. Your method also should also work
Read Chapter 4 Creating user Interface by Retro Meier Professional Android Devleopment
I am trying to make a custom view using XML then retrieve its properties and edit them. This custom view is added into the test2 view several times with different id's for each. I have tried to retrieve the id for one of these custom views (player_1) then get the TextView (player_name), and edits its properties and no other views like the player_2 id view.
But I am not sure that this is this even possible? It renders fine, but I get an error every time I try to do this in code. I'm really not sure how to approach this, I can't seem to get inflate to work either to test that instead. Any ideaS?
Thanks!
Game.java
setContentView(R.layout.test2);
View player1 = (View) findViewById(R.id.player_1);
TextView player1Name = (TextView) player1.findViewById(R.id.player_name);
player1Name.setText("John");
test2.xml
<include
layout="#layout/player_view"
android:id="#+id/player_1"
/>
<include
layout="#layout/player_view"
android:id="#+id/player_2"
/>
player_view.xml
<?xml version="1.0" encoding="utf-8"?>
<merge
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:player="http://schemas.android.com/apk/res/com.example.android.merge">
<LinearLayout
android:id="#+id/top_view"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
>
<TextView
android:id="#+id/player_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
>
</TextView>
</LinearLayout>
</merge>
This is a cut down version of player_view.xml, I can post more if needed.
Also I have not worked out if it even prints the error message for this in eclipse, it goes into debug mode and does not explain any further what the issue is.
Your player_view.xml has unknown type, so the include is confused what kind of View is it. Try to do the next:
Use or create new PlayerView class, mergeable with player_view.xml.
Edit test2.xml to:
<PlayerView
android:id="#+id/player_1"
/>
<PlayerView
android:id="#+id/player_2"
/>
then inflate it in your code as following:
setContentView(R.layout.test2);
PlayerView player1 = (PlayerView) findViewById(R.id.player_1);
LayoutInflater inflate = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflate.inflate(R.layout.player_view, player1);
Do the same for player2.