Develop Reference

LinearLayoutParams are causing a casting issue

I must be missing something really stupid.
I have a LinearLayout in my view:
_editTextViews = (LinearLayout)findViewById(R.id.editDesAndLocViews);
I am trying to dynamically change the height of that view by setting the LayoutParams
I have two LinearLayout.LayoutParams
LinearLayout.LayoutParams collapsedParams;
LinearLayout.LayoutParams openParams;
that are set in the constructor like so:
collapsedParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,0);
openParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT);
But as soon as i try to apply one of those params to my LinearLayout, like so:
_editTextViews.setLayoutParams(collapsedParams);
I get the following FATAL EXCEPTION:
At first i thought my project needed to be cleaned as it seems to think i am trying to force a relative layout to use linear layout params, but everything is LinearLayout. The LinearLayout in question does contain a couple RelativeLayouts. I don't know if / why that would be the problem.
please help

Change your LayoutParamss' type to either ViewGroup.LayoutParams or RelativeLayout.LayoutParams.
The LayoutParams you apply have to match the parent layout of the view. LayoutParams define how a View is layed out in its parent view (layout). Because each layout type takes different parametres for laying out a view (e.g. only LinearLayout has weight, only RelativeLayout can use anchors), they all have their own LayoutParams.

android explaination addview & layoutparams during runtime

just want to know what happens when I set new layout params to a new instance of an ImageView and then add it on an empty layout. It seems like doing it reset the parent layout hosting the new ImageView and also reset position and size of every sibling ImageView.
So what happens? Parent layout takes the layoutparams of the child?
thanks

Layout params have direct affect to views which use that params. But that also affects other views under same parent. Think about width, height and weight attrs of linear layout params. For example, if you set a layout params which has a weight attr defined, this will all change the visual of your parent.
From the doc:
LayoutParams are used by views to tell their parents how they want to
be laid out.
Note:
A parent is a view group, a container for child views. There are some types of view groups, ie LinearLayout, RelativeLayout etc(subclasses of ViewGroup can be googled), and they have specific layout behaviours and LayoutParams. While adding views to view groups layout params are used (both on xml and programmatically) for setting position, width, height inside that view group(container).

edit layout of existing child in RelativeLayout

I have a RelativeLayout with a number of children. The RelativeLayout is the main layout of my activity. I need to add to one of the children the layout value layout_alignParentBottom="true". I need to do this programmatically. the link How to set the android property layout_alignParentBottom to a button dynamically is not working for me because, basically, I don't want to have to inflate the RelativeLayout as I already have it at the setContentView(...). Any ideas how to do this?

I figured it out:
RelativeLayout.LayoutParams layout = (LayoutParams) theChild.getLayoutParams();
layout.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);

How to set two layout one at top and anther at bottom

hi I have 2 layout inside a framelayout and i want one linearlayout at top and another at bottom where i will specify height for both the layouts
and how to set this parameter for the linearLayout "layout_gravity " by code not by XML

Use a surfaceView , the SurfaceView allows you to stack in the Z order.
Docs
make sure your surfaceView is under the views of the views you want to stack.
Hope this helps

first fetch the layout from id.
LinearLayout layout = (LinearLayout)findViewById(R.id.IDOFLAYOUT);
//the set the gravity by this method
layout.setGravity(Gravity.CENTER);

Can I add views to a scrollview without inflating/re-inflating layouts?

I would like to take an existing ScrollView with a view in it, and add more views, dynamically (at runtime) to the ScrollView container.
Is it possible to add these views without having to create a new layout and inflate it? If so, what's the general process for adding these views dynamically?
For the sake of this question, assume the views are TextView...
Thanks!

A ScrollView can only have one child, so it doesn't make sense to add more children to it directly. Lets say your ScrollView has a LinearLayout inside of it, then you can add more views to the LinearLayout:
LinearLayout layout = findViewById(R.id.my_linear_layout);
TextView textView = new TextView(this);
layout.addView(textView);