Develop Reference

How to extend layout?

I'm having trouble understanding why my extended layout isn't working. I made a class which goes
public class MyLayout extends RelativeLayout {
public MyLayout(Context context) {
super(context);
}
}
I wrote the XML as
<package.MyLayout
. . .
</package.MyLayout>
The method where I get the error is in the activity where I have called setContentView(R.layout.layout_relative).
I don't understand what I'm doing wrong because surely you inflate in the activity from the XML layout which is building on the custom class where I can make my overrides?

you need the other constructor, the one that takes two parameters:
public MyLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
which is used when the layout is inflated from the layout

You have specified the wrong constructors!
Android xml inflation uses
public RelativeLayout (Context context, AttributeSet attrs, int
defStyleAttr)
public RelativeLayout (Context context, AttributeSet
attrs, int defStyleAttr, int defStyleRes) since api 21

Custom view with children inside it(buttons, edittexts, etc.)

I have custom view which extends imageview (with glow touch). I want to add elements like buttons, textviews, to make glow touch when they are touched. I read that custom view cannot have children because only layouts can have them.
Is there any workaround to solve this stuff?
Code:
public class CustomView extends ImageView{
public CustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomView(Context context) {
super(context);
.........
}
With regards

You are correct about the fact that only layouts (ViewGroups) can contain Views, and Views itself can not.
Instead of making a custom View, you can make a custom ViewGroup. In there you can add the Views you need, like the ImageViews and the others you mention (Buttons, EditText, etc).

how to use a same custom fontface for all the view in android?

i want use all the component in android which having the same font type face, for that i am creating a individual custom class for each component like CustomTextView, CustomEditText, etc,..
So instead of creating a individual class for each component can i create a view CustomView class that will automatically apply style for all the components in android

Just declare your own TextView and use it in your XML, it should appear in the custom Views
public class MyTextView extends TextView {
public MyTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
setType(context);
}
public MyTextView(Context context, AttributeSet attrs) {
super(context, attrs);
setType(context);
}
public MyTextView(Context context) {
super(context);
setType(context);
}
private void setType(Context context){
this.setTypeface(Typeface.createFromAsset(context.getAssets(), "chalk_board.ttf"));
}
Oh dam u want it globally for all views, so this is the wrong approach.... Sorry for that

You have at least 2 ways:
create your own TextView class and set fontFace in constructor
you can use custom LayoutInflater. And every time view gets inflated check that it is textView (or other view not extending textView but having font settings) and set correct fontFace settings.

android: how to set custom font for entire application

I have developed a very huge application and now i have a requirement of having custom font for all controls in the application. so I want to know the better way to change the font in one shot. The application has more than a hundred XML layout. and i cant change all controls to a custom component with custom font. Please provide a solution to Change the font without altering all the controls in XML.

Do something like this
pacage com.prac;
class MyFontedTextView extends TextView {
public FontedTextView(Context context) {
super(context);
init();
}
public FontedTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public FontedTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
String otfName = "MyCustomOtfFileWhichIPutInAssetsFolder.otf";
Typeface font = Typeface.createFromAsset(context.getAssets(), otfName);
this.setTypeface(font);
}
}
Now replace this all over in xml file from your TextViews
<com.prac.MyFontedTextView .... instead of <TextView
This change you have to do all over for it to apply
also for the case of button text . Button is also subclass of TextView
So the same can work for button's too
Hope this help or can lead you to the solution you are looking

Android: using LayoutInflater.inflate to pass custom parameters to a constructor

This has been bothering me for a while, and none of my searching has yielded results. If I have a custom GUI element, I can use a LayoutInflater to inflate it as I would a normal component. The inflation call results in a call to my custom GUI element's constructor, and all is well.
However, what if I want to add a custom parameter to my element's constructor? Is there a way I can pass this parameter in using LayoutInflater?
For example:
In main xml, I have a holder for my layout:
<LinearLayout
android:id="#+id/myFrameLayoutHolder"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
</LinearLayout>
and a MyFrameLayout.xml file:
<com.example.MyFrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/MyFLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1 >
<!-- Cool custom stuff -->
</com.example.MyFrameLayout>
and an inflater call:
LayoutInflater MyInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LinearLayout myFLayoutHolder = (LinearLayout) findViewById(R.id.myFrameLayoutHolder);
MyFrameLayout L = ((MyFrameLayout) MyInflater.inflate(R.layout.MyFLayout, myFLayoutHolder, false));
myFLayoutHolder.addView(L);
If, in my class that extends FrameLayout, I add a parameter to my constructor, I get a crash:
public class MyFrameLayout extends FrameLayout {
private int myInt;
public MyFrameLayout(Context context) {
this(context, null);
}
public MyFrameLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0, 0);
}
public MyFrameLayout(Context context, AttributeSet attrs, int defStyle, int myParameter) {
super(context, attrs, defStyle);
myInt = myParameter;
//Amazing feats of initialization
}
}
Now, it's easy enough to work around this issue by defining a custom init method that I call right after layout inflation, but that seems clumsy to me. Is there a better way?

You cant define a constructor with your own parameter because your constructor signature conflicts with FrameLayout's own constructor signature and you are not calling super(context, attrs, defStyle);, instead you are calling super(context, attrs); which is incomplete for this constructor.
You must need to define all three native constructors exactly as they are:
FrameLayout(Context context)
FrameLayout(Context context, AttributeSet attrs)
FrameLayout(Context context, AttributeSet attrs, int defStyle)
What you can do is to use your own (custom) attributes in xml and then retrieve them in your MyFrameLayout's attrs object

If the custom component is inflate by XML file or inflate method. You dont´t pass elemnts in the construct because this is not support in android.