Problem with setLayoutParams method in android UI

Question

I am making an application in which I have to change the UI programmaticaly. I needed to change the layout_height and layout_width XML attributes.

But when I use the setLayoutParams method, the app runs and then I give a message that it has unexpectedly stopped working and I have to force close.

I have tried setting the LayoutParams as ViewGroup.LayoutParams as well. But nothing works. Kindly check the attached code and guide.

This is the Java Code.

private void fixLayoutVmain(){
    ListView lv;
    ImageButton rev,stop,play,forw;
    lv=(ListView)findViewById(R.id.ListMain);
    rev=(ImageButton)findViewById(R.id.rev);
    stop=(ImageButton)findViewById(R.id.stop);
    play=(ImageButton)findViewById(R.id.plpa);
    forw=(ImageButton)findViewById(R.id.forw);
    Log.d("DEV1","ID's have been assigned");
    LayoutParams lp=new LayoutParams(W, ((75*H)/100));      
    Log.d("DEV1","param object created");       
    lv.setLayoutParams(lp);     
    Log.d("DEV1","ListView param set");     
    lp.height=(int)(10*H)/100;
    lp.width=(int)(10*H)/100;
    Log.d("DEV1","Changes to param made");
    rev.setLayoutParams(lp);    
    Log.d("DEV1","Reverse Button param applied");
    stop.setLayoutParams(lp);
    Log.d("DEV1","Stop button param applied");
    play.setLayoutParams(lp);
    Log.d("DEV1","forward button param applied");
    forw.setLayoutParams(lp);
    Log.d("DEV1","All imagebutton changes have been made");

}

This is the XML File

<LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <ListVieW
        android:id="@+id/ListMain"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:orientation="horizontal"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:gravity="bottom">
            <ImageButton
                android:id="@+id/rev"
                android:src="@drawable/reverseimg"
                android:background="@null"
                android:scaleType="fitXY" />
            <ImageButton
                android:id="@+id/stop"
                android:src="@drawable/stopimg"
                android:background="@null"
                android:scaleType="fitXY" />
            <ImageButton
                android:id="@+id/plpa"
                android:src="@drawable/playimg"
                android:background="@null"
                android:scaleType="fitXY" />
            <ImageButton
                android:id="@+id/forw"
                android:src="@drawable/forwardimg"
                android:background="@null"
                android:scaleType="fitXY" />
    </LinearLayout>
</LinearLayout>

Answer 1

Any time you set LayoutParams, check the parent container of the View. In all your instances, the parent is a LinearLayout. You need to use LinearLayout.LayoutParams, like so:

LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(width, height);
lv.setLayoutParams(lp);

Whether that's your particular force close issue or not, we have no way of knowing. As stated in the comments, you should check LogCat and post the exception details here. Give this a try though, and see if it fixes the problem.