HelperUtil

HelperUtil.java

public class HelperUtil {

    public static HelperUtilBase getInstance(Context context) {

        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.KITKAT) {
            return new HelperUtilL(context);
        } else if (Build.VERSION.SDK_INT == Build.VERSION_CODES.KITKAT) {
            return new HelperUtilKK(context);
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            return new HelperUtilJB(context);
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            return new HelperUtilICS(context);
        } else {
            return new HelperUtilBase(context);
        }
    }


}

HelperUtilBase.java

public class HelperUtilBase  {

    protected Context mContext;

    public HelperUtilBase(Context context){
        this.mContext = context;
    }

    public void setActionBar() {
        // Do nothing pre-L
    }

    public void setElevation(View view, float elevation){
        // Do nothing pre-L
    }


}

HelperUtilKK.java

@TargetApi(Build.VERSION_CODES.KITKAT)
public class HelperUtilKK extends HelperUtilBase{

    public HelperUtilKK(Context context) {
        super(context);
    }
}

HelperUtilL.java

@TargetApi(Build.VERSION_CODES.L)
public class HelperUtilL extends HelperUtilBase{

    private Toolbar mActionBarToolbar;

    public HelperUtilL(Context context) {
        super(context);
    }

    @Override
    public void setElevation(View view, float elevation){
        view.setElevation(elevation);
    }

    @Override
    public void setActionBar() {
        mActionBarToolbar = (Toolbar) ((Activity)mContext).findViewById(R.id.toolbar);
        if (mActionBarToolbar != null) {
            ((Activity)mContext).setActionBar(mActionBarToolbar);
        }
    }

    //......

}

MyActivity,java

public class MyActivity extends Activity {

     HelperUtilBase helper;

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

        helper = HelperUtil.getInstance(this);

       //....
   
       helper.setActionBar();

       helper.setElevation(cardView, 4.0f);
    }

}