Question

I already have an XML layout with some buttons in it, and now i want to add a textview to the same layout, but in my Java class. I don’t get any errors until the “addView” line. I would also appreciate it if someone could tell me a better way to add onto a pre-existing XML layout in Java.

public class MyActivity extends Activity{
TextView textview;
RelativeLayout layout;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
layout=(RelativeLayout)findViewById(R.id.mylayout); 
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParam(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, RelativeLayout.TRUE);
textview=new TextView(this);
textview.setId(16);
textview.setText("Help");
layout.addView(textview, params);
setContentView(layout);
}

Answer 1

Your code should be like this, since you already have xml layout, you should first setContent to xml layout and then add new view to the Relativelayout.

public class MyActivity extends Activity{

TextView textview;
RelativeLayout layout;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.file_name);
    layout=(RelativeLayout)findViewById(R.id.mylayout); 
    RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParam(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
    params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, RelativeLayout.TRUE);
    textview=new TextView(this);
    textview.setId(16);
    textview.setText("Help");
    layout.addView(textview, params);
}