[Android] Rewrite native controls and use

[1] About the rewritten Class (here by Numberpciker as an example)

public class RakurakuNumberPicker extends NumberPicker {//[1]继承想要重写的控件
    //[2]必须完成其自身的构造函数（三个都写上最好）
    public RakurakuNumberPicker(Context context) {
        super(context);
    }

    public RakurakuNumberPicker(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RakurakuNumberPicker(Context context, AttributeSet attrs,
            int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
    //[3]贴上你自己添加的方法or重写的方法
    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {

        if (event.getKeyCode() == KeyEvent.KEYCODE_DPAD_LEFT) {
            SettingMessageNotificationTimeActivity.getInstance()
                    .updateArrowGuidanceUI(true);
        }
        if (event.getKeyCode() == KeyEvent.KEYCODE_DPAD_RIGHT) {
            SettingMessageNotificationTimeActivity.getInstance()
                    .updateArrowGuidanceUI(false);
        }
        return super.dispatchKeyEvent(event);
    }

}

[2] The method at the call site

    - A reference to the XML file (note the pose)

        <com.android.mms.ui.RakurakuNumberPicker
            android:id="@+id/notice_time_picker"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

 - Class file usage

//声明
private RakurakuNumberPicker mNoticeTimePicker;
//绑定
mNoticeTimePicker = (RakurakuNumberPicker)findViewById(R.id.notice_time_picker);

[3] Easter eggs (overridden View calls the method at the caller)

- Small episode, because static methods are required, all methods or members involved need to be static

This is clearly unacceptable

The final best solution

- Activity exposes a static method to get its object

    
    protected static SettingMessageNotificationTimeActivity sMe;

    public static SettingMessageNotificationTimeActivity getInstance() {
        return sMe;
    }

- The custom space gets the Activity object and then calls its method

            SettingMessageNotificationTimeActivity.getInstance().FunctionTest();