创建并显示视图

public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);

LinearLayout layout = (LinearLayout) getLayoutInflater().inflate(R.layout.activity_main);
// 添加一个Button
Button btn = new Button(this);
btn.setText("按键");
LinearLayout.LayoutParams lParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
layout.addView(btn, lParams);
// 视图与窗口关联
setContentView(layout);
}