android 中通过代码创建控件

package bvb.de.openadbwireless.circle;

import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.RelativeLayout.LayoutParams;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class AddViewByJava extends Activity {

    private Context context = this;
    private RelativeLayout rl_root;
    private TextView tv;

    @TargetApi(Build.VERSION_CODES.KITKAT)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 最外层的控件 RelativeLayout
        rl_root = new RelativeLayout(context);

        // 添加一个TextView
        tv = new TextView(context);
        RelativeLayout.LayoutParams tvLayoutParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        // 设置 margin
        tvLayoutParams.leftMargin = 50;
        // 设置 padding
        tv.setPadding(10, 10, 10, 10);
        tv.setText("textView");
        tv.setLayoutParams(tvLayoutParams);
        rl_root.addView(tv);

        //添加一个按钮
        Button btn = new Button(context);
        btn.setText("button");
        // 设置规则 : 在TextView 的下方
        RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        layoutParams.addRule(RelativeLayout.BELOW, tv.getId());
        btn.setLayoutParams(layoutParams);
        rl_root.addView(btn);
        btn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                tv.setText(getChild());
            }
        });

        // 在Button 下面添加一个LinearLayout,里面水平放4个Button
        LinearLayout ll = new LinearLayout(context);
        RelativeLayout.LayoutParams layoutParams1 = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        layoutParams1.addRule(RelativeLayout.BELOW, btn.getId());
        ll.setLayoutParams(layoutParams1);
        ll.setBackgroundColor(Color.GREEN);
        ll.setPadding(10, 50, 0, 0);
        rl_root.addView(ll);

        ll.setOrientation(LinearLayout.HORIZONTAL);
        int btnCount = 4;
        for (int i = 0; i < btnCount; i++) {
            final Button button = new Button(context);
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(new LinearLayout.LayoutParams(0, LayoutParams.WRAP_CONTENT));
            params.weight = 1;
            button.setText("button" + i);
            ll.addView(button, params);
            button.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    Toast.makeText(context, button.getText(), Toast.LENGTH_SHORT).show();
                }
            });
        }

        ListView lv = new ListView(context);
        RelativeLayout.LayoutParams layoutParams2 = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        layoutParams2.addRule(RelativeLayout.BELOW, ll.getId());
        lv.setLayoutParams(layoutParams2);
        rl_root.addView(lv);
        List<String> datas = new ArrayList<String>();
        for (int i = 0; i < 20; i++) {
            datas.add("name" + i);
        }
        lv.setAdapter(new ArrayAdapter<String>(context, android.R.layout.simple_list_item_1, android.R.id.text1, datas));

        setContentView(rl_root);
    }

    public String getChild() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < rl_root.getChildCount(); i++) {
            sb.append(rl_root.getChildAt(i).toString()).append("\n");
        }
        return sb.toString();
    }

}