I have a layout where I include the same sub-layout multiple times, each one with a different role:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<include
android:id="#+id/settings_eco_seekarc"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="#layout/settings_arc" />
<include
android:id="#+id/settings_comfort_seekarc"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="#layout/settings_arc" />
</LinearLayout>
It works if I find the views in this way:
View eco = root.findViewById(R.id.settings_eco_seekarc);
mEcoSeekArc = (SeekArc) eco.findViewById(R.id.settings_seekarc);
mEcoLeaf = (ImageView) eco.findViewById(R.id.settings_leaf_img);
mEcoText = (TextView) eco.findViewById(R.id.settings_text);
View cmf = root.findViewById(R.id.settings_comfort_seekarc);
mComfortSeekArc = (SeekArc) cmf.findViewById(R.id.settings_seekarc);
mComfortLeaf = (ImageView) cmf.findViewById(R.id.settings_leaf_img);
mComfortText = (TextView) cmf.findViewById(R.id.settings_text);
I am introducing ButterKnife in my project now, and I hoped I could simply annotate each view (the following obviously doesn't work, and I can see why) and inject them later using each included layout root:
#InjectView(R.id.settings_seekarc)
SeekArc mEcoSeekArc;
#InjectView(R.id.settings_leaf_img)
ImageView mEcoLeaf;
#InjectView(R.id.settings_text)
TextView mEcoText;
#InjectView(R.id.settings_seekarc)
SeekArc mComfortSeekArc;
#InjectView(R.id.settings_leaf_img)
ImageView mComfortLeaf;
#InjectView(R.id.settings_text)
TextView mComfortText;
//then later...
View eco = root.findViewById(R.id.settings_eco_seekarc);
ButterKnife.inject(this, eco);
View cmf = root.findViewById(R.id.settings_comfort_seekarc);
ButterKnife.inject(this, cmf);
Doing it in this way, though, leads me to this error at the second injection:
Error:(81, 13) error: Attempt to use #InjectView for an already
injected ID 2131493185 on 'mEcoSeekArc'.
My question is: is there a way to use ButterKnife in this scenario?
you could use some type of sub-container like this:
public static class SettingsArcLayout {
#InjectView(R.id.settings_text) public TextView mEcoText;
#InjectView(R.id.settings_leaf_img) public ImageView mComfortLeaf;
// etc...
}
then you have it
SettingsArcLayout layout1 = new SettingsArcLayout();
SettingsArcLayout layout2 = new SettingsArcLayout();
and then:
ButterKnife.inject(this); // inject eco and cmf
ButterKnife.inject(layout1, eco);
ButterKnife.inject(layout2, cmf);
and throught this class you can use:
layout1.mEcoText.setText(... etc
The idea of my answer is the same as Budius proposed, I found it in a related issue on ButterKnife's github repo. Original Author is TomazMartins
The MainActivity:
public MainActivity extends AppCompatActivity {
// 1. First, we declare the layout that was included as a View objects.
#BindView(R.id.layout_1) View layout_1;
#BindView(R.id.layout_2) View layout_2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 2. In here, we bind the included layouts
ButterKnife.bind(this);
// 4. Then, we create objects of the type of the IncludedLayout.
// In this example the layout reuse the same layout twice, so, there are two
// IncludedLayouts.
IncludedLayout includedLayout_1 = new IncludedLayout();
IncludedLayout includedLayout_2 = new IncludedLayout();
// 5. We bind the elements of the included layouts.
ButerKnife.bind(includedLayout_1, layout_1);
ButerKnife.bind(includedLayout_2, layout_2);
// 6. And, finally, we use them.
includedLayout_1.displayed_text.setText("Hello");
includedLayout_2.displayed_text.setText("Hey!");
}
// 3. We create a static class that will be an container of the elements
// of the included layout. In here we declare the components that
// hold this. In this example, there is only one TextView.
static class IncludedLayout {
#BindView(R.id.displayed_text) TextView displayed_text;
}
}
The XML of the MainAcitvity:
<!--...-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<include android:id="#+id/layout_1" layout="#layout/included_layout" />
<include android:id="#+id/layout_2" layout="#layout/included_layout" />
</LinearLayout>
<!--...-->
The XML of the Included Layout:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/displayed_text"/>
</LinearLayout>
That's it!
When i ran it, although the id was the same, because I reused it, the text in the TextView was different.
Related
I have a layout where I include the same sub-layout multiple times, each one with a different role:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<include
android:id="#+id/settings_eco_seekarc"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="#layout/settings_arc" />
<include
android:id="#+id/settings_comfort_seekarc"
android:layout_width="match_parent"
android:layout_height="match_parent"
layout="#layout/settings_arc" />
</LinearLayout>
It works if I find the views in this way:
View eco = root.findViewById(R.id.settings_eco_seekarc);
mEcoSeekArc = (SeekArc) eco.findViewById(R.id.settings_seekarc);
mEcoLeaf = (ImageView) eco.findViewById(R.id.settings_leaf_img);
mEcoText = (TextView) eco.findViewById(R.id.settings_text);
View cmf = root.findViewById(R.id.settings_comfort_seekarc);
mComfortSeekArc = (SeekArc) cmf.findViewById(R.id.settings_seekarc);
mComfortLeaf = (ImageView) cmf.findViewById(R.id.settings_leaf_img);
mComfortText = (TextView) cmf.findViewById(R.id.settings_text);
I am introducing ButterKnife in my project now, and I hoped I could simply annotate each view (the following obviously doesn't work, and I can see why) and inject them later using each included layout root:
#InjectView(R.id.settings_seekarc)
SeekArc mEcoSeekArc;
#InjectView(R.id.settings_leaf_img)
ImageView mEcoLeaf;
#InjectView(R.id.settings_text)
TextView mEcoText;
#InjectView(R.id.settings_seekarc)
SeekArc mComfortSeekArc;
#InjectView(R.id.settings_leaf_img)
ImageView mComfortLeaf;
#InjectView(R.id.settings_text)
TextView mComfortText;
//then later...
View eco = root.findViewById(R.id.settings_eco_seekarc);
ButterKnife.inject(this, eco);
View cmf = root.findViewById(R.id.settings_comfort_seekarc);
ButterKnife.inject(this, cmf);
Doing it in this way, though, leads me to this error at the second injection:
Error:(81, 13) error: Attempt to use #InjectView for an already
injected ID 2131493185 on 'mEcoSeekArc'.
My question is: is there a way to use ButterKnife in this scenario?
you could use some type of sub-container like this:
public static class SettingsArcLayout {
#InjectView(R.id.settings_text) public TextView mEcoText;
#InjectView(R.id.settings_leaf_img) public ImageView mComfortLeaf;
// etc...
}
then you have it
SettingsArcLayout layout1 = new SettingsArcLayout();
SettingsArcLayout layout2 = new SettingsArcLayout();
and then:
ButterKnife.inject(this); // inject eco and cmf
ButterKnife.inject(layout1, eco);
ButterKnife.inject(layout2, cmf);
and throught this class you can use:
layout1.mEcoText.setText(... etc
The idea of my answer is the same as Budius proposed, I found it in a related issue on ButterKnife's github repo. Original Author is TomazMartins
The MainActivity:
public MainActivity extends AppCompatActivity {
// 1. First, we declare the layout that was included as a View objects.
#BindView(R.id.layout_1) View layout_1;
#BindView(R.id.layout_2) View layout_2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 2. In here, we bind the included layouts
ButterKnife.bind(this);
// 4. Then, we create objects of the type of the IncludedLayout.
// In this example the layout reuse the same layout twice, so, there are two
// IncludedLayouts.
IncludedLayout includedLayout_1 = new IncludedLayout();
IncludedLayout includedLayout_2 = new IncludedLayout();
// 5. We bind the elements of the included layouts.
ButerKnife.bind(includedLayout_1, layout_1);
ButerKnife.bind(includedLayout_2, layout_2);
// 6. And, finally, we use them.
includedLayout_1.displayed_text.setText("Hello");
includedLayout_2.displayed_text.setText("Hey!");
}
// 3. We create a static class that will be an container of the elements
// of the included layout. In here we declare the components that
// hold this. In this example, there is only one TextView.
static class IncludedLayout {
#BindView(R.id.displayed_text) TextView displayed_text;
}
}
The XML of the MainAcitvity:
<!--...-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<include android:id="#+id/layout_1" layout="#layout/included_layout" />
<include android:id="#+id/layout_2" layout="#layout/included_layout" />
</LinearLayout>
<!--...-->
The XML of the Included Layout:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/displayed_text"/>
</LinearLayout>
That's it!
When i ran it, although the id was the same, because I reused it, the text in the TextView was different.
obviously not a profound question, but I think theres probably an error in my approach.
So I've added the file listview.xml to my project in the layout folder.
it contains this:
<?xml version="1.0" encoding="utf-8"?>
<ListView android:id="#+id/android:list"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android" />
I've also tried:
<?xml version="1.0" encoding="utf-8"?>
<ListView android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android" />
And i my main activity function generally looks like this:
public class ToDoManagerActivity extends ListActivity {
private static final int ADD_TODO_ITEM_REQUEST = 0;
private static final String FILE_NAME = "TodoManagerActivityData.txt";
private static final String TAG = "Lab-UserInterface";
// IDs for menu items
private static final int MENU_DELETE = Menu.FIRST;
private static final int MENU_DUMP = Menu.FIRST + 1;
ToDoListAdapter mAdapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a new TodoListAdapter for this ListActivity's ListView
mAdapter = new ToDoListAdapter(getApplicationContext());
// Put divider between ToDoItems and FooterView
getListView().setFooterDividersEnabled(true);
// TODO - Inflate footerView for footer_view.xml file
TextView footerView = (TextView) getLayoutInflater().inflate(R.layout.footer_view, null);
// NOTE: You can remove this block once you've implemented the assignment
if (null == footerView) {
return;
}
// TODO - Add footerView to ListView
getListView().addFooterView(footerView);
setListAdapter(mAdapter);
setContentView(R.layout.footer_view);
This keeps breaking with the error:
...java.lang.RunTimeException: content must have a ListView whose id attribute is 'android.R.id.list'
I noticed that if I comment out the setContentView(R.layout.footer_view) bit the error disappears, which is quite confusing as well, because it seems like the error should trigger before there.
This is confusing the hell out of me because as far as I can tell this element exists. Its seems like maybe I'm missing a step to load the ListView? I'm banging my head against the wall here and this seems like something really basic, and being a n00b sucks...So any help is much appreciated!
Cheers!
EDIT:
footer_view.xml contents:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/footerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="#string/add_new_todo_item_string"
android:textSize="24sp" >
</TextView>
EDIT2:
Current onCreate after suggested edits:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create a new TodoListAdapter for this ListActivity's ListView
mAdapter = new ToDoListAdapter(getApplicationContext());
// Put divider between ToDoItems and FooterView
getListView().setFooterDividersEnabled(true);
setListAdapter(mAdapter);
TextView footerView = (TextView) getLayoutInflater().inflate(R.layout.footer_view, getListView(), false);
getListView().addFooterView(footerView);
}
For an Activity that is extending ListActivity, the ListView needs to exist within the xml file that you are using in the activity, in your case that's the footer_view file.
Taken from the Google Dev Site - "ListActivity has a default layout that consists of a single, full-screen list in the center of the screen. However, if you desire, you can customize the screen layout by setting your own view layout with setContentView() in onCreate(). To do this, your own view MUST contain a ListView object with the id "#android:id/list""
To incorporate your footer below your list, try this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<TextView
android:id="#+id/footerView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="#string/add_new_todo_item_string"
android:textSize="24sp" >
</TextView>
</LinearLayout>
Here, try this in your layout:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/black"
android:id="#android:id/list" />
</LinearLayout>
That is exactly what I have in my app.
Then in your onCreate(), just this:
setContentView(R.layout.activity_main);
Try it and let me know if it works. That code should work. From there, we can continue on to isolate the problem.
EDIT:
Man, now I see your problem. Not a big deal here. Let's look at your code (edited to be shorter). The onCreate() method has this:
super.onCreate(savedInstanceState);
mAdapter = new ToDoListAdapter(getApplicationContext());
getListView().setFooterDividersEnabled(true);
TextView footerView = (TextView) getLayoutInflater().inflate(R.layout.footer_view, null);
getListView().addFooterView(footerView);
setListAdapter(mAdapter);
setContentView(R.layout.footer_view);
Do you see R.layout.activity_main anywhere there? There's your issue! Your R.layout.footer_view only contains a textview, it doesn't contain the ListView, and your Activity keeps looking for the ListView that you promised it that you'd have by extending a ListActivity.
Try this - change your onCreate() method to this:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAdapter = new ToDoListAdapter(getApplicationContext());
setListAdapter(mAdapter);
}
Then your activity_main.xml layout file should look like this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/black"
android:id="#android:id/list" />
</LinearLayout>
This should work. Let me know.
EDIT2:
Now add this to the end of your onCreate() method:
TextView footerView = (TextView) getLayoutInflater().inflate(R.layout.footer_view, null);
getListView().addFooterView(footerView);
Voila! Should work now.
Though this tends to be very basic question, i cannot solve this issue. I searched the similar kind of issue but none solves my issue.
I created my own class where i created some basic controls and i called this class in my xml as
<com.mypackagename.classname
..
..
/>
and some views goes inside this. and before this now i would like to add relativelayout as
activity_main1.xml:
<RelativeLayout xmlns:android="schemas.android.com/apk/res/android"
xmlns:android1="http://schemas.android.com/apk/res/android"
android1:layout_width="match_parent"
android1:layout_height="wrap_content" >
<com.test.MainLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/mainlayout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ImageView
android:id="#+id/drawer_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:src="#drawable/ic_drawer" />
</LinearLayout>
</com.test.MainLayout>
</RelativeLayout >
and i my main activity i declared as
MainActivity:
Myview view;
view = (Myview)this.getLayoutInflater().inflate(R.layout.activity_main1, null);
setContentView(view);
where MyView is the class where i have my own controls.
After adding relative layout i tried something like
MainActivity1.java:
public class MainActivity1 extends FragmentActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
RelativeLayout item = (RelativeLayout)findViewById(R.id.item);
view = (Myview)this.getLayoutInflater().inflate(R.layout.activity_main1, null);
item.addView(view);
setContentView(item); // facing an error here
.......... rest of the code
}
and my layout activity is
public class MainLayout1 extends LinearLayout
{
....
}
while running it is throwing classcastexception and the error is
java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to com.view.layout.MainLayout
view = (Myview)this.getLayoutInflater().inflate(R.layout.activity_main1, null);
At this point in your java class, you are getting MyView Object in view, but it is actually a layout file instance which returns its parent layout here its a RelativeLayout.
Since inflate(R.layout.activity_main1, null); returns the object of RelativeLayout. Instead of this you have to get instance of your MainLayout1 like(R.id.mainlayout) and then cast it into the MyView object like:
RelativeLayout item = (View)this.getLayoutInflater().inflate(R.layout.activity_main1,null);
view = (Myview) item.findViewById(R.id.mainlayout);
item.addView(view);
setContentView(item);
I have 2 layout xml files: "highlights.xml" and "highlights_cell.xml".
Here is a simplified version of each. I've removed the width/height/etc and just kept the important attributes...
highlights.xml
<LinearLayout>
<uk.co.jasonfry.android.tools.ui.SwipeView android:id="#+id/swipe_view" />
<uk.co.jasonfry.android.tools.ui.PageControl android:id="#+id/page_control" />
</LinearLayout>
highlights_cell.xml
<LinearLayout android:orientation="vertical">
<LinearLayout android:id="#+id/linear_layout1" android:orientation="horizontal">
<ImageView android:id="#+id/logo" />
<LinearLayout android:id="#+id/linear_layout2" android:orientation="vertical">
<TextView android:id="#+id/title" />
<TextView android:id="#+id/subtitle" />
</LinearLayout>
</LinearLayout>
<ScrollView android:id="#+id/scroll_view">
<TextView android:id="#+id/description" />
</ScrollView>
</LinearLayout>
The idea is that I want to add several "highlights_cell" to "highlights" through a loop.
I've thrown together some test code as follows but, as it's not working, I suspect that I'm not adding the cell layouts correctly, or perhaps I shouldn't be using "inflater"...
/** Declare shared variables */
SwipeView mSwipeView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState){
//Initialise layout and variables
super.onCreate(savedInstanceState);
setContentView(R.layout.highlights);
//Setup controls
mSwipeView = (SwipeView) findViewById(R.id.swipe_view);
LayoutInflater inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
//Loop through collection and add views
for(int i=0; i<7;i++)
{
//Create the itemView to use layout xml for each cell
View itemView = inflater.inflate(R.layout.highlights_cell, null);
//Set values within cell
TextView title = (TextView) itemView.findViewById(R.id.title);
title.setText("HELLO WORLD_" + i);
//add the itemView to main view
mSwipeView.addView(itemView);
}
}
Is this the correct way to add layouts dynamically to a parent layout?
Thanks!
It looks good except for a few things.
Because you are adding views to your custom ViewGroup, you will have to be sure that it correctly lays out and displays its children.
Also, when you add a View to a ViewGroup, you specify the LayoutParams that views can have in that ViewGroup.
Some more info about creating a custom ViewGroup
http://about-android.blogspot.com/2010/05/create-dynamic-view-group.html
custom ViewGroup example?
I want to show two views in one activity. If I clicked on button in the first view I want to see the second and other way round.
The views should not have the same size as the screen so I want e.g. to center it, like you see in first.xml.
But if I add the views with
addContentView(mFirstView, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
the views are not centered. They are shown at top left.
How can I use the xml settings to e.g. center it?
first.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_height="wrap_content" android:layout_width="wrap_content"
android:background="#drawable/background"
android:layout_gravity="center"
android:minWidth="100dp"
android:minHeight="100dp"
android:paddingBottom="5dp"
>
<LinearLayout android:id="#+id/head"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageButton android:id="#+id/first_button"
android:src="#drawable/show_second"
android:layout_gravity="center"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#null" />
</LinearLayout>
second.xml same as first.xml but with
<ImageButton android:id="#+id/second_button"
android:src="#drawable/show_first"
... />
ShowMe.java
public class ShowMe extends Activity {
View mFirstView = null;
View mSecondView = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initFirstLayout();
initSecondLayout();
showFirst();
}
private void initFirstLayout() {
LayoutInflater inflater = getLayoutInflater();
mFirstView = inflater.inflate(R.layout.first, null);
getWindow().addContentView(mFirstView, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
ImageButton firstButton = (ImageButton)mMaxiView.findViewById(R.id.first_button);
firstButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
ShowMe.this.showSecond();
}
});
}
private void initSecondLayout() {
// like initMaxiLayout()
}
private void showFirst() {
mSecondView.setVisibility(View.INVISIBLE);
mFirstView.setVisibility(View.VISIBLE);
}
private void showSecond() {
mFirstView.setVisibility(View.INVISIBLE);
mSecondView.setVisibility(View.VISIBLE);
}}
Hope someone can help.
Thanks
Why don't you use setContentView(R.layout.yourlayout)? I believe the new LayoutParams you're passing in addContentView() are overriding those you defined in xml.
Moreover, ViewGroup.LayoutParams lacks the layout gravity setting, so you would have to use the right one for the layout you're going to add the view to (I suspect it's a FrameLayout, you can check with Hierarchy Viewer). This is also a general rule to follow. When using methods that take layout resources as arguments this is automatic (they might ask for the intended parent).
With this consideration in mind, you could set your layout params with:
FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(/* wrap wrap */);
lp.setGravity(Gravity.CENTER);
addContentView(mYourView, lp);
But I would recommend setContentView() if you have no particular needs.
EDIT
I mean that you create a layout like:
~~~/res/layout/main.xml~~~
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="....."
android:id="#+id/mainLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
then in your onCreate() or init...Layout():
setContentView(R.layout.main);
FrameLayout mainLayout = (FrameLayout)findViewById(R.id.mainLayout);
// this version of inflate() will automatically attach the view to the
// specified viewgroup.
mFirstView = inflater.inflate(R.layout.first, mainLayout, true);
this will keep the layout params from xml, because it knows what kind it needs. See reference.