以编程方式创建视图时如何知道要使用哪个 LayoutParams 类？

Question

Every ViewGroup class implements a nested class that extends ViewGroup.LayoutParams . So we LinearLayout.LayoutParams , RelativeLayout.LayoutParams , FrameLayout.LayoutParams etc.

Suppose I want to create a View , eg TextView programmatically. I will have to give it the required properties, like layout_width and layout_height , for which I will have to use a LayoutParams class. How will I know which LayoutParams class to use?

Answer 1

It depends on what you're putting it into. If you're putting it into a linear layout, use LinearLayout.LayoutParams. For relative, use RelativeLayout.LayoutParams.

If you don't know the type- add it first via add, then use getLayoutParams to get it. Then change the layourparams. When you use the add() that doesn't take a params, the parent will make one for you.

Answer 2

If you only need view width and height, use a ViewGroup.LayoutParams, as all the other ones inherit from this one. You can assign a ViewGroup.LayoutParams where a RelativeLayout.LayoutParams, LinearLayout.LayoutParams, ... is expected.