如何用java代码写android的jiemian

package com.example.code;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  // setContentView(R.layout.activity_main);
  LinearLayout linearlayout = new LinearLayout(this);//创建布局
  linearlayout.setOrientation(LinearLayout.VERTICAL);// 设置布局方向
  LinearLayout.LayoutParams layoutparams = new LinearLayout.LayoutParams(
    ViewGroup.LayoutParams.FILL_PARENT,
    ViewGroup.LayoutParams.FILL_PARENT);//设置布局的宽高
  
  ViewGroup.LayoutParams tvparams = new LinearLayout.LayoutParams(
    ViewGroup.LayoutParams.FILL_PARENT,
    ViewGroup.LayoutParams.FILL_PARENT);//设置tv的宽高的参数

 

  TextView tv = new TextView(this);//创建textview
  tv.setText(R.string.hello_world);//设置textview的文本
  
  
  linearlayout.addView(tv, tvparams);//想补救中添加控件
  setContentView(linearlayout, layoutparams);
  
  

 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.activity_main, menu);
  return true;
 }

}