Width of LayoutParams is ignored for the outer view when set in java code (instead of xml layout)

Question

I create a very simple activity where I create and set the view in java code instead of xml. The width I pass to the outer LinearLayout though has no effect at all (200). The view is displayed on the entire width of the screen, no matter what value I pass here.

(Note that this is just sample code; I know that in a real app you don't use fixed values. I just want to point out my problem here for easier clarification).

public class MyActivity extends Activity {

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

        // outer linear layout
        LinearLayout ll = new LinearLayout(this);
        ll.setLayoutParams(new LinearLayout.LayoutParams(
                200,   // *** this param has no effect, regardless of the value I set here ***
                LinearLayout.LayoutParams.FILL_PARENT
        ));
        ll.setBackgroundColor(Color.parseColor("#00ff00"));


        // inner linear layout
        LinearLayout ll2 = new LinearLayout(this);
        ll2.setLayoutParams(new LinearLayout.LayoutParams(
                100,    // ** this width for the inner view is working fine **
                LinearLayout.LayoutParams.FILL_PARENT
        ));
        ll2.setBackgroundColor(Color.parseColor("#0000ff"));
        ll.addView(ll2);

        setContentView(ll);
    }
}

But if I replace setContentView(ll); and use a xml layout instead where the outer LinearLayout has a value of 200px, it's applied properly and the view only takes 200px of the screen.

setContentView(com.example.R.layout.main);

where main.xml is:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="200px"
    android:layout_height="fill_parent"
    android:background="#ff0000"
    >
    <TextView  
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello"
        />
</LinearLayout>

Why does setting a fixed width in java code for the outer layout has no effect?

Answer 1

Hi,

You can try this way.

  LinearLayout ll = new LinearLayout(this);       
  LinearLayout.LayoutParams lparam = new LinearLayout.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.FILL_PARENT);
  lparam.width = 200;

  ll.setLayoutParams(lparam);
  ll.setBackgroundColor(Color.parseColor("#00ff00"));

  setContentView(ll);

Answer 2

I figure it's a bug in Android, filed a bug report at

http://code.google.com/p/android/issues/detail?id=12244

Answer 3

I can't tell you 'why' exactly, but perhaps the xml has a sort of 'invisible parent' to provide an anchor. If you're desperate for a workaround, then the obvious answer is to wrap it with an invisible outer parent like this:

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

    // very, very outer Linear layout!
    LinearLayout ll_InvisibleParent = new LinearLayout(this);
    ll_InvisibleParent.setBackgroundColor(Color.parseColor("#000000"));

    // outer Linear layout
    LinearLayout ll = new LinearLayout(this);
    //
    ll.setLayoutParams(new LinearLayout.LayoutParams(
            200,   // *** this param has no effect, regardless of the value I set here ***
            LinearLayout.LayoutParams.FILL_PARENT
    ));
    ll.setBackgroundColor(Color.parseColor("#00ff00"));// green

    // inner Linear layout
    LinearLayout ll2 = new LinearLayout(this);
    ll2.setLayoutParams(new LinearLayout.LayoutParams(
            100,    //  this width for the inner view is working fine 
            LinearLayout.LayoutParams.FILL_PARENT
    ));
    ll2.setBackgroundColor(Color.parseColor("#0000ff"));// blue
    ll.addView(ll2);
    //setContentView(ll); REPLACED WITH INVISIBLE PARENT
    ll_InvisibleParent.addView(ll);
    setContentView(ll_InvisibleParent);
}

that works for me