Android以编程方式设置底边距

Question

Is it possible to use RelativeLayout.LayoutParams to specify a bottom margin for an object? I would like to specify the bottom margin only.

Answer 1

try like this .

TextView mTvLine = findViewById(R.id.tv_line);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
// add rule
params.addRule(RelativeLayout.ALIGN_BOTTOM,R.id.ll_status);
params.setMargins(0, 0, 0, 0);
mTvLine.setLayoutParams(params);

NOTE

RelativeLayout.LayoutParams relativeLayoutParams = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);

// Child widget relative to the widget: imageViewId is ABOVE of it
relativeLayoutParams.addRule(RelativeLayout.ABOVE, imageViewId.getId());

// Child widget relative to the widget: imageViewId is BELOW of it
relativeLayoutParams.addRule(RelativeLayout.BELOW, imageViewId.getId());

//  Child widget relative to the widget: aligned with the bottom of the imageViewId
relativeLayoutParams.addRule(RelativeLayout.ALIGN_BOTTOM, imageViewId.getId());

// The following three methods represent the same, indicating that the child widget is at the bottom of the parent widget
relativeLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, -1);//
relativeLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, RelativeLayout.TRUE);
relativeLayoutParams.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);  

Answer 2

Yes is possible, but it could be an indication that what you want to do could be done in a more appropriate way. So, what's the reasoning behind this request?

In case you really need to do it programmatically instead of via xml layout, you can do it like this:

View myView = findViewById(R.layout.my_view);
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) view.getLayoutParams();
params.bottomMargin = 23;  // your new value, in pixels
view.setLayoutParams(params);

Two details to be careful: margins are in pixels, but xml layouts are in dps; also, for each view type you'll need to cast to its own specific layout parameters type.