How to resize a custom view programmatically?

Question

Android throws an exception if you fail to pass the height or width of a view. Instead of creating a new LayoutParams object, use the original one, so that all other set parameters are kept. Note that the type of LayoutParams returned by getLayoutParams is that of the parent layout, not the view you are resizing.

RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) someLayout.getLayoutParams();
params.height = 130;
someLayout.setLayoutParams(params);

this.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, theSizeIWant));

Problem solved!

NOTE: Be sure to use the parent Layout's LayoutParams. Mine is LinearLayout.LayoutParams!

This works for me:

ViewGroup.LayoutParams params = layout.getLayoutParams();
params.height = customHeight;
layout.requestLayout();

For what it's worth, let's say you wanted to resize the view in device independent pixels (dp): -

You need to use a method called applyDimension, that's a member of the class TypedValue to convert from dp to pixels. So if I want to set the height to 150dp (say) - then I could do this:

float pixels = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 150, getResources().getDisplayMetrics());
LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) someLayout.getLayoutParams();
params.height = (int) pixels;
someLayout.setLayoutParams(params);

where the expression: getResources().getDisplayMetrics() gets the screen density/resolution

In Kotlin, you can use the ktx extensions:

yourView.updateLayoutParams {
   height = <YOUR_HEIGHT>
}

Here's a more generic version of the solution above from @herbertD :

private void resizeView(View view, int newWidth, int newHeight) { 
    try { 
        Constructor<? extends LayoutParams> ctor = view.getLayoutParams().getClass().getDeclaredConstructor(int.class, int.class); 
        view.setLayoutParams(ctor.newInstance(newWidth, newHeight));   
    } catch (Exception e) { 
        e.printStackTrace(); 
    }
}

try a this one:

...
View view = inflater.inflate(R.layout.active_slide, this);
view.setMinimumWidth(200);