Develop Reference

how to set a customview to center of an activity in android?

I have made a customView for a .gif image support in android. I got success in that, but currently that view is aligned to the top left corner of my activity. I want it to be aligned to the center of my activity. Please tell me how can I do this.
My code is as below:
GifwebView view = new GifwebView(this, "file:///android_asset/p3.gif");
view.setBackgroundColor(Color.parseColor("#00000000"));
RelativeLayout rel = (RelativeLayout) findViewById(R.id.rl_pics);
RelativeLayout.LayoutParams p = new RelativeLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
rel.setBackgroundColor(Color.parseColor("#00000000"));
view.setLayoutParams(p);
rel.addView(view);
CustomView
public class GifwebView extends WebView {
public GifwebView(Context context, String path) {
super(context);
// TODO Auto-generated constructor stub
loadUrl(path);
}
}

Your activity main layout (RelativeLayout), it's height and width should be match_parent, so it will take the whole screen, and it's gravity should be set to center, so that the elements in it will be positioned to center of the screen.
XML:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/rl_pics"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center">
</RelativeLayout>
Activity:
RelativeLayout rel = (RelativeLayout) findViewById(R.id.rl_pics);
RelativeLayout.LayoutParams p = new RelativeLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
GifwebView view = new GifwebView(this, "file:///android_asset/p3.gif");
view.setBackgroundColor(Color.parseColor("#00000000"));
view.setLayoutParams(p);
rel.addView(view);

p.addRule(RelativeLayout.CENTER_HORIZONTAL);
view.setGravity(Gravity.CENTER_VERTICAL);
This should work. Also if you want the activity to take the whole screen instead of the requiered for filling your content you should use match_parent instead of wrap_content.
edit: if your custom view doesn't implement the setGravity(int) method, you can do this instead:
p.addRule(RelativeLayout.CENTER_HORIZONTAL|RelativeLayout.CENTER_IN_PARENT, view.getId());

How to add Buttons dynamically into ScrollView

I'm having a difficulty adding buttons dynamically to a ScrollView. The code below is adding the buttons BUT there is no scroller.
If I'm putting the buttons directly in the XML (not dynamically) it's working and I can scroll down/up.
My view:
<ScrollView android:id="#+id/ScrollView01"
android:layout_width="264dp"
android:layout_height="match_parent"
android:fillViewport="true"
>
<LinearLayout
android:id="#+id/buttons"
android:layout_width="264dp"
android:layout_height="wrap_content"
android:orientation="vertical"
android:scrollbars="vertical"
>
** HERE THE BUTTONS SHOULD BE ADDED DYNAMICALLY **
</LinearLayout>
</ScrollView>
The code which adding buttons:
// create new button
final Button newbutton = new Button(this);
// set background color
newbutton.setBackgroundColor(Color.GRAY);
// set width and height
newbutton.setWidth(50);
newbutton.setHeight(20);
// set position
newbutton.setY(((float)numOfButton*20)+20);
newbutton.setX(100);
// set text
newbutton.setText(Integer.toString(numOfButton));
// create patameter
final LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT
);
//set listener
android.view.View.OnClickListener buttonListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
// make all the DrawView invisible
for(View view : comments){
view.setVisibility(View.INVISIBLE);
}
// set the chosen comment visible
comments.get(numOfButton).setVisibility(View.VISIBLE);
boardsHandler.setCurrenBoard(numOfButton);
}};
newbutton.setOnClickListener(buttonListener);
// creating a thread to add button
buttons.post(new Runnable() {
#Override
public void run() {
buttons.addView(newbutton, p);
}
});
Is it something with the LinearLayout.LayoutParams p ?
Thanks!

Try following code
first do
LinearLayout myContainer = findViewById(R.id.layoutId);
When you set parameters for a view, they need to correspond to the parent view for your widget.
LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.FILL_PARENT);
finally add button as you are doing.
try and tell if it works

Setting X and Y position will not work. The LinearLayout layouts it's children vertically or horizontally, only taking their width/height into account.
Besides this -- have you tried calling buttons.invalidate() after buttons.addView(...). This should refresh the layout and should show your newbutton.

This is a rather old post but I found it quickly when doing research on that kind of problem. So I'll post am answer anyway, maybe it'll be of help to anyone..
I had a similar problem with a relative layout to which buttons were added dynamically. I found a workaround in defining the layout's size manually when adding the buttons. For your case, adding the line
buttons.getLayoutParams().height = numOfButton*20+40;
after
buttons.addView(newbutton, p);
might help, though it's probably not the best solution.
I thought my mistake was using the RelativeLayout at all, but since you appear to have the same problem...
Ever thought of using a table layout?

How to set layout_gravity programmatically?

My question is simple,
How to set my buttons layout_gravity programmatically?
I found this on internet, but it simply throws me a Nullpointer exception:
Button MyButton = new Button(this);
LinearLayout.LayoutParams lllp=(LinearLayout.LayoutParams)MyButton.getLayoutParams();
lllp.gravity=Gravity.RIGHT;
MyButton.setLayoutParams(lllp);
MyLinearLayout.addView(MyButton);
Any solution?

Java
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
params.weight = 1.0f;
params.gravity = Gravity.TOP;
button.setLayoutParams(params);
Kotlin
val params = LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT
).apply {
weight = 1.0f
gravity = Gravity.TOP
}
For gravity values and how to set gravity check Gravity.
Basically, you should choose the LayoutParams depending on the parent. It can be RelativeLayout, LinearLayout etc...

I'd hate to be resurrecting old threads but this is a problem that is not answered correctly and moreover I've ran into this problem myself.
Here's the long bit, if you're only interested in the answer please scroll all the way down to the code:
android:gravity and android:layout_gravity works differently. Here's an article I've read that helped me.
GIST of article: gravity affects view after height/width is assigned. So gravity centre will not affect a view that is done FILL_PARENT (think of it as auto margin). layout_gravity centre WILL affect view that is FILL_PARENT (think of it as auto pad).
Basically, android:layout_gravity CANNOT be access programmatically, only android:gravity.
In the OP's case and my case, the accepted answer does not place the button vertically centre.
To improve on Karthi's answer:
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.CENTER;
button.setLayoutParams(params);
Link to LinearLayout.LayoutParams.
android:layout_gravity shows "No related methods" meaning cannot be access programatically.
Whereas gravity is a field in the class.

I had a similar problem with programmatically setting layout_gravity on buttons in a GridLayout.
The trick was to set gravity on the button layoutParams AFTER the button was added to a parent (GridLayout), otherwise the gravity would be ignored.
grid.addView(button)
((GridLayout.LayoutParams)button.getLayoutParams()).setGravity(int)

MyButton.setGravity(Gravity.RIGHT);
For layout_gravity use the answer stated by "karthi". This method sets gravity to place the children inside the view.

layoutParams2.gravity = Gravity.RIGHT|Gravity.BOTTOM;
use this to add mor than one gravity

If you want to change the layou_gravity of an existing view do this:
((FrameLayout.LayoutParams) view.getLayoutParams()).gravity = Gravity.BOTTOM;
Remember to use the right LayoutParams based on the Layout type your view is in. Ex:
LinearLayout.LayoutParams

KOTLIN setting more than one gravity on FrameLayout without changing size:
// assign more than one gravity,Using the operator "or"
var gravity = Gravity.RIGHT or Gravity.CENTER_VERTICAL
// update gravity
(pagerContainer.layoutParams as FrameLayout.LayoutParams).gravity = gravity
// refresh layout
pagerContainer.requestLayout()

This question is old but I just had the same problem and solved it like this
LayoutParams lay = new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT)
lay.gravity = Gravity.CENTER;

I use someting like that: (Xamarin and C# code)
LinearLayout linLayout= new LinearLayout(this);
linLayout.SetGravity(GravityFlags.Center);
TextView txtView= new TextView(this);
linLayout.AddView(txtView);
the SetGravity puts my textView in the center of the layout.
So SetGravity layout property refer to layout content

In case you need to set Gravity for a View use the following
Button b=new Button(Context);
b.setGravity(Gravity.CENTER);
For setting layout_gravity for the Button
use gravity field for the layoutparams as
LayoutParams lp=new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
lp.gravity=Gravity.CENTER;
try this
hope this clears
thanks

If you want to put a view in the center of parent, you can do with following code..
public class myLayout extends LinearLayout {
public myLayout(Context context) {
super(context);
RelativeLayout vi = (RelativeLayout) ((LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(
R.layout.activity_main, null);
LinearLayout.LayoutParams cc = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
cc.gravity = Gravity.CENTER;
this.setGravity(Gravity.CENTER);
this.addView(vi);
}
}
these code section make LinearLayout put the first view elements in the center of parent.
So, we system don't consider the initial width and high to arrange view in the center .
I do the code section well.

The rest of the answers are right, I want to add more explaination. The layout_gravity is about how to position the view in parent view.
You must set gravity **after method parentView.addView() ** was called. We can see the code:
public void setLayoutParams(ViewGroup.LayoutParams params) {
if (params == null) {
throw new NullPointerException("Layout parameters cannot be null");
}
mLayoutParams = params;
resolveLayoutParams();
if (mParent instanceof ViewGroup) {
((ViewGroup) mParent).onSetLayoutParams(this, params);
}
requestLayout();
}
And the problem of null pointer is because it's not calling addView before getLayoutParams().
The annotation was already said "This method may return null if this View is not attached to a parent ViewGroup or {#link#setLayoutParams(android.view.ViewGroup.LayoutParams)} was not invoked successfully. When a View is attached to a parent ViewGroup, this method must not return null."

to RelativeLayout, try this code , it works for me:
yourLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);

Perfectly Working!!! None of the above answer works for me. In Xml file setting gravity and setting layout_gravity is different. Check out the below code
// here messageLL is the linear layout in the xml file
// Before adding any view just remove all views
messageLL.removeAllViews();
// FrameLayout is the parent for LinearLayout
FrameLayout.LayoutParams params = new
FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
params.gravity = Gravity.CENTER|Gravity.CENTER_VERTICAL;
messageLL.setLayoutParams(params);
messageText.setVisibility(View.GONE);
messageNoText.setVisibility(View.VISIBLE);
messageLL.addView(messageNoText);
Also check This,where you can find clear explanation about gravity and layout_gravity .

Most of above answer are right, so written a helper methods, so you can use it
directly in you project .
set layout_gravity programmtically
// gravity types : Gravity.BOTTOM, Gravity.START etc.
// view : can be any view example : button, textview, linearlayout, image etc.
// for single view
public static void setLayoutGravity(int gravity, View view){
((LinearLayout.LayoutParams) view.getLayoutParams()).gravity = gravity;
}
// for mulitple views
public static void setLayoutGravity(int gravity, View ...view){
for(View item : view)
((LinearLayout.LayoutParams) item.getLayoutParams()).gravity = gravity;
}

Modify the existing layout params and set layout params again
//Get the current layout params and update the Gravity
(iv.layoutParams as FrameLayout.LayoutParams).gravity = Gravity.START
//Set layout params again (this updates the view)
iv.layoutParams = layoutParams

I switched from LinearLayout.LayoutParams to RelativeLayout.LayoutParams to finally get the result I was desiring on a custom circleview I created.
But instead of gravity you use addRule
RelativeLayout.LayoutParams mCircleParams = new RelativeLayout.LayoutParams(circleheight,circleheight);
mCircleParams.addRule(RelativeLayout.CENTER_IN_PARENT);

int width=getResources().getDisplayMetrics().widthPixels;
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams
(width, width);
params.gravity = Gravity.CENTER;
iv_main_text = new HTextView(getContext());
iv_main_text.setLayoutParams(params);
iv_main_text.setBackgroundColor(Color.BLUE);
iv_main_text.setTextSize(60);
iv_main_text.setGravity(Gravity.CENTER);
iv_main_text.setTextColor(Color.BLACK);

FloatingActionButton sendFab = new FloatingActionButton(this);
FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
layoutParams.setMargins(32, 32, 32, 32);
layoutParams.gravity = Gravity.END|Gravity.BOTTOM;
sendFab.setLayoutParams(layoutParams);
sendFab.setImageResource(android.R.drawable.ic_menu_send);

Try this code
Button btn = new Button(YourActivity.this);
btn.setGravity(Gravity.CENTER | Gravity.TOP);
btn.setText("some text");
or
btn.setGravity(Gravity.TOP);

Place view inside FrameLayout in Android

I want to add a view inside a FrameLayout programmatically and to place it in a specific point within the layout with a specific width and height. Does FrameLayout support this? If not, should I use an intermediate ViewGroup to achieve this?
int x; // Can be negative?
int y; // Can be negative?
int width;
int height;
View v = new View(context);
// v.setLayoutParams(?); // What do I put here?
frameLayout.addView(v);
My initial idea was to add an AbsoluteLayout to the FrameLayout and place the view inside the AbsoluteLayout. Unfortunately I just found out that AbsoluteLayout is deprecated.
Any pointers will be much appreciated. Thanks.

The following example (working code) shows how to place a view (EditText) inside of a FrameLayout. Also it shows how to set the position of the EditText using the setPadding setter of the FrameLayout (everytime the user clicks on the FrameLayout, the position of the EditText is set to the position of the click):
public class TextToolTestActivity extends Activity{
FrameLayout frmLayout;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
frmLayout = (FrameLayout)findViewById(R.id.frameLayout1);
frmLayout.setFocusable(true);
EditText et = new EditText(this);
frmLayout.addView(et,100,100);
frmLayout.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
Log.i("TESTING","touch x,y == " + event.getX() + "," + event.getY() );
frmLayout.setPadding(Math.round(event.getX()),Math.round(event.getY()) , 0, 0);
return true;
}
});
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<FrameLayout
android:id="#+id/frameLayout1"
android:layout_height="fill_parent" android:layout_width="fill_parent">
</FrameLayout>
</LinearLayout>

You can also add a margin around the newly added view to position it inside the FrameLayout.
FrameLayout frameLayout = (FrameLayout) findViewById(R.id.main); // or some other R.id.xxx
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.setMargins(0, metrics.heightPixels - 20, 0, 0);
View v = new View(context);
v.setLayoutParams(params);
frameLayout.addView(v);
This will position the FrameLayout 20 pixels from the bottom of the screen.
Edit: completed the example so it stands by itself. And oh, yes it does work.

It's true that with FrameLayout all children are pegged to the top left of the screen, but you still have some control with setting their padding. If you set different padding values to different children, they will show up at different places in the FrameLayout.

From the link Quinn1000 provided:
You can add multiple children to a FrameLayout, but all children are pegged to the top left of the screen.
This means you can't put your View at a specific point inside the FrameLayout (except you want it to be at the top left corner :-)).
If you need the absolute positioning of the View, try the AbsoluteLayout:
A layout that lets you specify exact locations (x/y coordinates) of its children. Absolute layouts are less flexible and harder to maintain than other types of layouts without absolute positioning.
As for setting the width and height of the View, also like Quinn1000 said, you supply the v.setLayoutParams() method a LayoutParams object, depending on the container you chose (AbsoluteLayout, LinearLayout, etc.)

The thread here on stackOverflow at
How do you setLayoutParams() for an ImageView?
covers it somewhat.
For instance:
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(30, 30);
yourImageView.setLayoutParams(layoutParams);
implies that you need to be defining a LinearLayout.LayoutParams (or in your case a FrameLayout.layoutParams) object to pass to the setLayoutParams method of your v object.
At
http://developer.android.com/reference/android/widget/FrameLayout.html
it almost makes it looks like you could ask your v to:
generateDefaultLayoutParams () via this method if you have not defined the parameters specifically.
But it's late, and those links are making my eyes bleed a little. Let me know if they nhelp any :-)

How to layout zoom Control with setBuiltInZoomControls(true)?

would like to add a zoom control to the map. I also want to layout the position of the zoom Control instead of the default middle bottom position. I can do this by getZoomControl but it is deprecated.
Could anyone tell me how to do this with setBuildtInZoomControls?

This is how I got mine working finally (by embedding a ZoomControl in XML layout).
mapView = (MapView) this.findViewById(R.id.mapView);
ZoomControls zoomControls = (ZoomControls) findViewById(R.id.zoomcontrols);
zoomControls.setOnZoomInClickListener(new OnClickListener() {
public void onClick(View v) {
mapView.getController().zoomIn();
}
});
zoomControls.setOnZoomOutClickListener(new OnClickListener() {
public void onClick(View v) {
mapView.getController().zoomOut();
}
});
See: Always show zoom controls on a MapView

mapView.getZoomButtonsController()
Although this is undocumented (at least in the javadoc available here: com.google.android.maps) I am quite sure this is the replacement for the deprecated getZoomControls
Edit: just found out that it is documented, just not in the google api docs but rather here: ZoomButtonsController on developer.android.com
You could then call getContainer () or getZoomControls () (depending on what you want to do) to get access to the zoom controls view.
And then do something like
RelativeLayout.LayoutParams zoomParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
zoomParams.addRule(RelativeLayout.ALIGN_PARENT_TOP);
mapView.getZoomButtonsController().getZoomControls().setLayoutParams(zoomParams);
although I have to admit that I am not sure what layout the maps view uses, could be LinearLayout as well.

LinearLayout zoomLayout = (LinearLayout) findViewById(R.id.layout_zoom);
View mapController = mapView.getZoomButtonsController().getZoomControls();
zoomLayout.addView(mapController, new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

I'm pretty sure that the only way to do this is to either use the MapView's deprecated getZoomControls() or to DIY it. The MapController has the methods necessary (e.g. zoomIn() and zoomOut()).

RelativeLayout relativeLayout = new RelativeLayout(this);
setContentView(relativeLayout);
final MapView mapView = new MapView(this, DEBUG_MAP_API_KEY);
RelativeLayout.LayoutParams mapViewLayoutParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT,RelativeLayout.LayoutParams.FILL_PARENT );
relativeLayout.addView(mapView, mapViewLayoutParams);
RelativeLayout.LayoutParams zoomControlsLayoutParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,RelativeLayout.LayoutParams.WRAP_CONTENT );
zoomControlsLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
zoomControlsLayoutParams.addRule(RelativeLayout.CENTER_HORIZONTAL);
relativeLayout.addView(mapView.getZoomControls(), zoomControlsLayoutParams);
mapView.setClickable(true);
mapView.setEnabled(true);
I think this should work ... Hope this is useful :)

The solution provided by George on Placing Zoom Controls in a MapView allows to layout the built in zoom controls by using gravity attributes. This attribute positions the element into its container which seems that is positioned on the bottom of the screen so its not possible to position the zoom controls on the top of the screen by layouting the zoom controls.
In conclusion you can layout the built in zoom controls by doing:
((FrameLayout.LayoutParams) mapView.getZoomButtonsController().getZoomControls().getLayoutParams()).gravity = Gravity.RIGHT;
Remember that the zoom controls are contained into a FrameLayout therefore any try to use rules like RelativeLayout.ALIGN_PARENT_BOTTOM or RelativeLayout.ALIGN_PARENT_TOP will lead you only to pain and sorrow.