MyCustomView.java

public class MyCustomView extends View {
	public MyCustomView(Context context) { this(context, R.style.MyCustomView); }

	public MyCustomView(Context context, AttributeSet attrs) { this(context, attrs, 0); }

	public MyCustomView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        final int defStyleRes = 0;
        final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MyCustomView, defStyle, defStyleRes);
        try {
			this.search_width = a.getDimension(R.styleable.MyCustomView_search_width, 123); // a fallback default value...
			this.search_height = a.getDimension(R.styleable.MyCustomView_search_height, 456);
			/* ... i'm lazy to type the rest...... */
		} finally {
		    /* call recycle() after you're done. */
			a.recycle();
		}
	}
}

res_values-w480dp_styles.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
	<style name="MyCustomView">
    	<item name="search_width">300dp</item>
        <item name="search_height">50dp</item>
        <item name="f1_column_width">25dp</item>
        <item name="f3_column_width">280dp</item>
        <item name="f4_column_width">45dp</item>
        <item name="edittext_height">30dp</item>
    </declare-styleable>
</resources>

res_values_attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <!-- the name doesn't have to be the same as the class name of your 
         custom view, but we usually use the same name to avoid obfuscation. -->
    <declare-styleable name="MyCustomView">
        <attr name="search_width" format="dimension"/>
        <attr name="search_height" format="dimension"/>
        <attr name="f1_column_width" format="dimension"/>
        <attr name="f3_column_width" format="dimension"/>
        <attr name="f4_column_width" format="dimension"/>
        <attr name="edittext_height" format="dimension"/>
    </declare-styleable>
</resources>

res_values_styles.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
	<style name="MyCustomView">
    	<item name="search_width">150dp</item>
        <item name="search_height">50dp</item>
        <item name="f1_column_width">25dp</item>
        <item name="f3_column_width">140dp</item>
        <item name="f4_column_width">45dp</item>
        <item name="edittext_height">30dp</item>
    </declare-styleable>
</resources>