Your code is *NOT* equivalent to the XML. You are using the wrong
LayoutParams everywhere. A widget must have the LayoutParams of its
*parent*. Therefore, the rows must have TableLayout.LayoutParams, the
TextViews must have TableRow.LayoutParams and the TableLayout must
have FrameLayout.LayoutParams.

Here is your code, corrected, and it works just fine.

package com.test;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;

public class Test extends Activity {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(buildTableViewFromSource());
        }

        private View buildTableViewFromSource() {
                FrameLayout.LayoutParams pTable = new FrameLayout.LayoutParams(
                                TableRow.LayoutParams.FILL_PARENT,
                                TableRow.LayoutParams.FILL_PARENT);

                TableLayout table = new TableLayout(this);
                table.setBackgroundColor(Color.RED);
                table.setLayoutParams(pTable);

                TableRow rowTop = new TableRow(this);

                TableLayout.LayoutParams pRowTop = new TableLayout.LayoutParams(
                                TableLayout.LayoutParams.FILL_PARENT,
                                TableLayout.LayoutParams.WRAP_CONTENT);
                pRowTop.weight = 1;

                rowTop.setBackgroundColor(Color.BLUE);

                TextView txt = new TextView(this);
                txt.setText("Top Content");

                rowTop.addView(txt, new TableRow.LayoutParams(
                                TableRow.LayoutParams.FILL_PARENT,
                                TableRow.LayoutParams.WRAP_CONTENT));

                TableRow rowBottom = new TableRow(this);
                rowBottom.setBackgroundColor(Color.GREEN);

                TextView txtBottom = new TextView(this);
                txtBottom.setText("Bottom Content");

                TableLayout.LayoutParams pRowBottom = new 
TableLayout.LayoutParams(
                                TableLayout.LayoutParams.WRAP_CONTENT,
                                TableLayout.LayoutParams.WRAP_CONTENT);

                rowBottom.addView(txtBottom, new TableRow.LayoutParams(
                                TableRow.LayoutParams.FILL_PARENT,
                                TableRow.LayoutParams.WRAP_CONTENT));

                table.addView(rowTop, pRowTop);
                table.addView(rowBottom, pRowBottom);

                return table;
        }
}