Creating LinearLayout in Java - Elements are not shown

I am trying to create a LinearLayout with TextViews in Java, because the number of elements is dynamically specified so using XML won't work out for me. Here is a little sample of my Code:

public class MyActivity extends Activity {

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

    LinearLayout layout = new LinearLayout(this);
    layout.setOrientation(LinearLayout.VERTICAL);
    layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));


    TextView titleView = new TextView(this);
    titleView.setWidth(LayoutParams.WRAP_CONTENT);
    titleView.setHeight(LayoutParams.WRAP_CONTENT);
    titleView.setTextAppearance(this, android.R.attr.textAppearanceLarge);
    titleView.开发者_运维问答setText("Hallo Welt!");
    layout.addView(titleView);

    setContentView(layout);

}
}

When i start this activity it does not show this TextView but it also does not show an error. Does anyone have an advice?

Try this,

  LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.VERTICAL);
        layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

        TextView titleView = new TextView(this);
        LayoutParams lparams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        titleView.setLayoutParams(lparams);
        titleView.setTextAppearance(this, android.R.attr.textAppearanceLarge);
        titleView.setText("Hallo Welt!");
        layout.addView(titleView);

        setContentView(layout);

TextView titleView = new TextView(this);
    titleView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
    titleView.setTextAppearance(this, android.R.attr.textAppearanceLarge);
    titleView.setText("Hallo Welt!");
    layout.addView(titleView);
    setContentView(layout);

Use this code:

    LinearLayout layout = new LinearLayout(this);
    layout.setOrientation(LinearLayout.VERTICAL);
    layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

    TextView titleView = new TextView(this);
    titleView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
    titleView.setTextAppearance(this, android.R.attr.textAppearanceLarge);
    titleView.setText("Hallo Welt!");
    layout.addView(titleView);

    setContentView(layout);

try this

titleView.setWidth(100);
titleView.setHeight(40);

or

   titleView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));