Develop Reference

Add two View to RelativeLayout.BELOW

I have RelativeLayout on all height and it has two View:
1) 'mainItem' is View to fix height;
2) 'listView' from rubber(or not fix) height;
I want that 'mainItem' stay on top and 'listView' was below 'mainView' and it stretched at all the rest height RelativeLayout.
I do so:
mainItem = new ItemList(getContext());
mainItem.setId(0);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
params.addRule(ALIGN_PARENT_TOP);
addView(mainItem, params);
listView = new ListView(getContext());
listView.setAdapter(adapter);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
params.addRule(BELOW, mainItem.getId());
addView(listView, params);
I get 'listView' stay on top and stretched at all width and height.
A 'mainItem' stay on top too but under 'listView'. ('mainView' not visible)
Please tell me, what I'm doing wrong?

Do not set the id to be 0. Put some other number and see if that works?
If you have a look at the docs for setID() you will see that it says "The identifier should be a positive number". Zero is not a positive number.
http://developer.android.com/reference/android/view/View.html#setId(int)

how to change the width of a button dynamically

I have a method that creates several buttons
public Button[] generaBottoniRisposta(int numeroBottoni, Context context){
Button bottoni[]= new Button[numeroBottoni];
/*genero un tot di bottoni in base a numeroBottoni, è necessario avere il context*/
for(int i=0; i < bottoni.length;i++){
bottoni[i] = new Button(context);
bottoni[i].setId(i);
bottoni[i].setText(String.valueOf(i+1));
LayoutParams param = new LinearLayout.LayoutParams(50, 50);
bottoni[i].setLayoutParams(param);
}
return bottoni;
}
and then another method that add them to a gridlayout.
I want to set the width of those buttons, but i'm not able to do it.
I tried a lot of stuff, setWidth(), setMaxWidth(), invalidate() etc.
Something weird happens. If I try to make the button bigger than its default size it works, if i try to make the button smaller than its default size it doesn't work!
How should I do? thank you

Try using LayoutParams, something like..
RelativeLayout.LayoutParams rel_bottone = new RelativeLayout.LayoutParams(buttonWidth, buttonHeight);
button.setLayoutParams(rel_bottone);
And the layout depends on the parent layout that contains the buttons..

I think setlayoutparams should do what you want. Like in the answer in this thread.
Set View Width Programmatically

try this:
LinearLayout.LayoutParams params = button.getLayoutParams();
params.width = 100;
button.setLayoutParams(params);
one more thing LinearLayout.LayoutParams is used when parent is a LinearLayout and when parent is RelativeLayout use RelativeLayout.LayoutParams.

Try something like this :
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(width, height);
button.setLayoutParams(params);

My buttons are inside a gridlayout. I tried to use GridLayout.LayoutParams giving the width of the cells, instead of trying to set the width of the button, and now it seems to work.
this is the code I use to add the buttons to the GridLayout
Spec row = GridLayout.spec(numeroRiga, 1);
Spec colspan = GridLayout.spec(numeroColonna, 1);
GridLayout.LayoutParams gridLayoutParam = new GridLayout.LayoutParams(row,colspan);
gridLayoutParam.width=50;
gridLayoutParam.height=50;
gridLayout.addView(button,gridLayoutParam);
But i'm wondering if i can set the width of the buttons in a similar way.

Theme.Dialog creates too small screen

I have an activity with ListView that has:
android:theme="#android:style/Theme.Dialog"
in Manifest.
When I open it and when it has only one line in ListView, the window that opens is very small.
How do I make the window take the whole screen?

Use this in your onCreate method of the Activity to make it full screen.
#Override
protected void onCreate(Bundle arg0) {
super.onCreate(arg0);
setContentView(R.layout.myxml);
LayoutParams params = getWindow().getAttributes();
params.height = LayoutParams.MATCH_PARENT;
params.width = LayoutParams.MATCH_PARENT;
getWindow().setAttributes((android.view.WindowManager.LayoutParams) params);
}

I have found that setting the window size does work, but you have to do it a bit later. In this example the window width is set to 90% of the display width, and it is done in onStart() rather than onCreate():
#Override
protected void onStart() {
super.onStart();
// In order to not be too narrow, set the window size based on the screen resolution:
final int screen_width = getResources().getDisplayMetrics().widthPixels;
final int new_window_width = screen_width * 90 / 100;
LayoutParams layout = getWindow().getAttributes();
layout.width = Math.max(layout.width, new_window_width);
getWindow().setAttributes(layout);
}

Similar to the answer from PravinCG but it can be done with one line in onCreate()...
getWindow().setLayout(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

Use the suggested code before setcontentview() call. It will work.

Just a small update. Used MATCH_PARENT instead of the deprecated FILL_PARENT. PravinCG's answer worked great for me.

Yeezz ! I figured it out ! The problem is that the margin sizes are not calculated in the window widht. So If you set the layout margin to 0 and move that part to the padding of the layout the problem will be solved.

Setting width to wrap_content for TextView through code

Can anyone help me how to set the width of TextView to wrap_content through code and not from XML?
I am dynamically creating a TextView in code ,so is there anyway to how to set its width to wrap_content through code?

TextView pf = new TextView(context);
pf.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
For different layouts like ConstraintLayout and others, they have their own LayoutParams, like so:
pf.setLayoutParams(new ConstraintLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
or
parentView.addView(pf, new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

There is another way to achieve same result. In case you need to set only one parameter, for example 'height':
TextView textView = (TextView)findViewById(R.id.text_view);
ViewGroup.LayoutParams params = textView.getLayoutParams();
params.height = ViewGroup.LayoutParams.WRAP_CONTENT;
textView.setLayoutParams(params);

Solution for change TextView width to wrap content.
textView.getLayoutParams().width = ViewGroup.LayoutParams.WRAP_CONTENT;
textView.requestLayout();
// Call requestLayout() for redraw your TextView when your TextView is already drawn (laid out) (eg: you update TextView width when click a Button).
// If your TextView is drawing you may not need requestLayout() (eg: you change TextView width inside onCreate()). However if you call it, it still working well => for easy: always use requestLayout()
// Another useful example
// textView.getLayoutParams().width = 200; // For change `TextView` width to 200 pixel

A little update on this post: if you are using ktx within your Android project, there is a little helper method that makes updating LayoutParams a lot easier.
If you want to update e.g. only the width you can do that with the following line in Kotlin.
tv.updateLayoutParams { width = WRAP_CONTENT }

I am posting android Java base multi line edittext.
EditText editText = findViewById(R.id.editText);/* edittext access */
ViewGroup.LayoutParams params = editText.getLayoutParams();
params.height = ViewGroup.LayoutParams.WRAP_CONTENT;
editText.setLayoutParams(params); /* Gives as much height for multi line*/
editText.setSingleLine(false); /* Makes it Multi line */

I think this code answer your question
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams)
holder.desc1.getLayoutParams();
params.height = RelativeLayout.LayoutParams.WRAP_CONTENT;
holder.desc1.setLayoutParams(params);

How do you setLayoutParams() for an ImageView?

I want to set the LayoutParams for an ImageView but cant seem to find out the proper way to do it.
I can only find documentation in the API for the various ViewGroups, but not an ImageView. Yet the ImageView seems to have this functionality.
This code doesn't work...
myImageView.setLayoutParams(new ImageView.LayoutParams(30,30));
How do I do it?

You need to set the LayoutParams of the ViewGroup the ImageView is sitting in. For example if your ImageView is inside a LinearLayout, then you create a
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(30, 30);
yourImageView.setLayoutParams(layoutParams);
This is because it's the parent of the View that needs to know what size to allocate to the View.

Old thread but I had the same problem now. If anyone encounters this he'll probably find this answer:
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(30, 30);
yourImageView.setLayoutParams(layoutParams);
This will work only if you add the ImageView as a subView to a LinearLayout. If you add it to a RelativeLayout you will need to call:
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(30, 30);
yourImageView.setLayoutParams(layoutParams);

If you're changing the layout of an existing ImageView, you should be able to simply get the current LayoutParams, change the width/height, and set it back:
android.view.ViewGroup.LayoutParams layoutParams = myImageView.getLayoutParams();
layoutParams.width = 30;
layoutParams.height = 30;
myImageView.setLayoutParams(layoutParams);
I don't know if that's your goal, but if it is, this is probably the easiest solution.

An ImageView gets setLayoutParams from View which uses ViewGroup.LayoutParams. If you use that, it will crash in most cases so you should use getLayoutParams() which is in View.class. This will inherit the parent View of the ImageView and will work always. You can confirm this here: ImageView extends view
Assuming you have an ImageView defined as 'image_view' and the width/height int defined as 'thumb_size'
The best way to do this:
ViewGroup.LayoutParams iv_params_b = image_view.getLayoutParams();
iv_params_b.height = thumb_size;
iv_params_b.width = thumb_size;
image_view.setLayoutParams(iv_params_b);

In order not to lose the rest of the parameters, you need to do as shown below:
Drawable drawable = ResourcesCompat.getDrawable(getResources(), R.drawable.checked, null);
preview.setImageDrawable(drawable);
ViewGroup.LayoutParams layoutParams = preview.getLayoutParams();
layoutParams.width = 100;
layoutParams.height = 98;
preview.setLayoutParams(layoutParams);