使用代码编写android UI

package cn.itcast.codeui;

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

public class DemoActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout ll = new LinearLayout(this);
        ll.setOrientation(LinearLayout.VERTICAL);
        LinearLayout.LayoutParams params =  new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT,LinearLayout.LayoutParams.FILL_PARENT);
        ll.setLayoutParams(params);
        
        TextView tv = new TextView(this);
        tv.setText(R.string.hello);
     
        
        ll.addView(tv, ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        
        EditText et = new EditText(this);
        ll.addView(et, ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        setContentView(ll);
       // setContentView(R.layout.main);
        
    }
}