android - Creating a button in Java, causes getLayoutParams to return null

Question

I need to create a button in Java. Below is my code:

 Button b = new Button(MyClass.this);
 b.requestLayout();
 LayoutParams lp = b.getLayoutParams();
 lp.height = LayoutParams.WRAP_CONTENT;
 lp.width = LayoutParams.WRAP_CONTENT;
 b.setLayoutParams(lp);
 b.setText("bla");
 b.setTextSize(16);
 b.setOnClickListener(myListener);

I then add this button to the bottom of a ListView:

 getListView().addFooterView(b);

However this crashes, because getLayoutParams returns null.

Even if I create new LayoutParams instead of getLayoutParams, i.e.:

 Button b = new Button(MyClass.this);
 LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
 b.setLayoutParams(lp); 
 b.setText("bla");
 b.setTextSize(16);
 b.setOnClickListener(myListener);

then the application crashes. Without setLayoutParams, it runs fine, but my button is not sized properly.

How can I size my button?

Answer 1

You have to add this button to a view if you want to get LayoutParams from button. Or just create new LayoutParams and set it.