RelativeLayout relativeLayout;  //declare this globally

现在，在任何函数中，如onCreate, onResume

relativeLayout = new RelativeLayout(this);  
relativeLayout.setBackgroundResource(R.drawable.view); //or whatever your image is
setContentView(relativeLayout); //you might be forgetting this

试试下面的代码:

Drawable thumb = ContextCompat.getDrawable(getActivity(), R.mipmap.cir_32);
mSeekBar.setThumb(thumb);

setBackground(getContext().getResources().getDrawable(R.drawable.green_rounded_frame));

RelativeLayout relativeLayout;  //declare this globally

现在，在任何函数中，如onCreate, onResume

relativeLayout = new RelativeLayout(this);  
relativeLayout.setBackgroundResource(R.drawable.view); //or whatever your image is
setContentView(relativeLayout); //you might be forgetting this

试试ViewCompat。setBackground (yourView drawableBackground)

你也可以设置任何图片的背景:

View v;
Drawable image=(Drawable)getResources().getDrawable(R.drawable.img);
(ImageView)v.setBackground(image);