Question

Ok, I’ve read around that a custom view must have a constructor with AttributeSet in order for findViewById() to work. I’ve not seen any actual implementation yet.

Below are my codes:
My custom view that extends HorizontalScrollView:

public AnimatedMenuBar(Context context) {
        // TODO Auto-generated constructor stub
        this(context, null);
    }

    public AnimatedMenuBar(Context context, AttributeSet attrs) {
        // TODO Auto-generated constructor stub
        this(context, attrs, 0);
    }

    public AnimatedMenuBar(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
        this.context = context;
        inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.main, this);
        this.setHorizontalScrollBarEnabled(false);
    }

From my main activity:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.testing);
        AnimatedMenuBar animatedMenuBar = (AnimatedMenuBar)findViewById(R.id.animatedMenuBar);
}

testing.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent">
    <com.pt.task.custommenubar.AnimatedMenuBar
        android:id="@+id/animatedMenuBar" android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

main.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="wrap_content" >
    <LinearLayout android:id="@+id/horizontalLayout" android:orientation="horizontal"
        android:layout_width="fill_parent" android:layout_height="wrap_content">
        <TextView android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/dummyTextView" android:padding="5dip"/>
    </LinearLayout>
</merge>

animatedMenuBar is always null, is there any thing that I missed?

Thank you very much!

Answer 1

I have met with such a bug.

1. Try Project-clean. Sometimes it helps.
2. If AnimatedMenuBar insied custommenubar, then write com.pt.task.custommenubar$AnimatedMenuBar
3. Try to rename AnimatedMenuBar everywhere in code.