MResource

public class MResource {
	public static int getIdByName(Context context, String className, String name) {
		String packageName = context.getPackageName();
		Class r = null;
		int id = 0;
		try {
			r = Class.forName(packageName + ".R");

			Class[] classes = r.getClasses();
			Class desireClass = null;

			for (int i = 0; i < classes.length; ++i) {
				if (classes[i].getName().split("\\$")[1].equals(className)) {
					desireClass = classes[i];
					break;
				}
			}

			if (desireClass != null)
				id = desireClass.getField(name).getInt(desireClass);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (NoSuchFieldException e) {
			e.printStackTrace();
		}

		return id;
	}
}

setContentView(MResource.getIdByName(getApplication(), "layout", "layout_main"));