Question

android中那个方法可以在java代码，而不是xml布局文件中让一个button居于屏幕中央，求解答

Answer 1

在代码中使用RelativeLayout实现即可，下面是详细步骤：
RelativeLayout mLayout = new RelativeLayout(this);
mLayout.setLayoutParams(new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.FILL_PARENT,
RelativeLayout.LayoutParams.FILL_PARENT));

Button mButton = new Button(this);
RelativeLayout.LayoutParams mParams = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT,
RelativeLayout.LayoutParams.WRAP_CONTENT);
mParams.addRule(RelativeLayout.CENTER_IN_PARENT);
mButton.setLayoutParams(mParams);
mButton.setText("Center");

mLayout.addView(mButton);
setContentView(mLayout);