Number picker wheel android

NumberPicker

Компонент NumberPicker находился в разделе Advanced старых версий студии. Компонент позволяет выбрать нужное число из заданного диапазона. Принцип работы похож на револьверный барабан — можно прокручивать числа в одну или другую сторону. Когда будет достигнут заданный предел, то числа продолжат изменяться в заданном диапазоне.

Учитывая, что компонент убрали из студии, можно предположить, что он оказался не очень востребованным.

Разместим компонент на экране.

Несмотря на то, что есть атрибут orientation, толку от него немного. Работает только вертикальный режим.

Добавляем немного кода:

Мы определили максимальное и минимальные числа для нашего вида. Удивительно, но через XML нельзя установить эти значения. Запустив проект, вы можете теперь выбрать нужное число через стрелочки. Недавно проверял на другом телефоне (API 19) — стрелочек уже не было.

Метод setWrapSelectorWheel() с параметром false может отключить бесконечную прокрутку:

Пример на Kotlin

Добавим на экран текстовую метку, чтобы отслеживать текущее выбранное значение.

Выбрать кота (Kotlin)

Мы можем заменить числа на свои значения через метод setDisplayedValues() (Java), например, на имена котов. В этом случае компонент приобретает какой-то смысл.

Про остальные методы почитайте в документации.

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Android NumberPickers

Oct 26, 2018 · 3 min read

In this tutorial you will learn how to create NumberPicker widgets in Android Studio with custom values and how to retrieve NumberPicker values.

What are NumberPickers?

NumberPickers are a widget avalible in Android Studio. They are a set of values selectable by either a horizontal or vertical scrolling wheel.

Creating a NumberPicker

To create a NumberPicker, go to the XML file of your main activity. Switch from the Design tab to the Text tab and type

When y o u switch back to the Design tab, the NumberPicker should be visible. The NumberPicker in the XML will look different from the NumberPicker in the app. Under ID, name the NumberPicker with the what_where_why naming scheme. In this case it will be numberpicker_main_picker. Don’t forget to constrain your NumberPicker! For this example the picker is centered horizontally and vertically.

In your MainActivity, create a NumberPicker variable and wire it to the NumberPicker you created in your XML.

Setting Custom Values

To set custom values on your NumberPicker, first set a minimum and maximum value. In this example we will have 5 values, so we will set the range to:

A NumberPicker takes an array of Strings as its values. First create an instance variable of a string array, then initialize the array with your desired values.

Next, set the NumberPicker values to these Strings with .setDisplayedValues()

When the program is run, it should look like this:

*note: the best way to format this code is to handle it under an initializePicker(); method, then run the method in onCreate. However, for the sake of simplicity in this tutorial, I will not be doing this.*

Retrieving NumberPicker Values

To get the value of your NumberPicker every time it is changed, create an onValueChangeListener in onCreate. In the overriden onValueChange method, create an int variable to store the picker value. Next, make a Log.d to log what the picker value is.

With the code we currently have, the NumberPicker value will be an int. To retrieve the String value of the picker we must access the String array storing our picker values. Rather than just logging the value of picker1, we must log pickerVals[valuePicker1].

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Number picker wheel android

Another NumberPicker with more flexible attributes on Android platform

some android projects use the android.widget.NumberPicker to provide alternative choices, but the default style of NumberPicker has some inflexible attibutes, and complicated to be customized.This NumberPickerView extends from View, and provide a friendly experience.

picking an item dynamically

a small project powered by NumberPickerView, a view which can pick or jump to a certain date with two modes, in Gregorian mode or in Chinese Lunar mode. The gif seem to be a little lag, but actually it runs smoothly. Check the project here: https://github.com/Carbs0126/GregorianLunarCalendar

NumberPickerView extends from View and has almost all functions of android.widget.NumberPicker except inputting fuction by EditText, but it has some advanced features, here are these two views’ differences below:

Features of android.widget.NumberPicker

1. the NumberPicker’s viewport can only show three items;
2. the value of friction is big, you can not pick a new value smoothly by fling;
3. no animation if you use setValue() in java code to set to a new value;
4. no animation if you use setDisplayValues() to change the content of NumberPicker;
5. has a bug if you set wrap mode by using setWrapSelectorWheel() , sometimes NumberPicker will not refresh canvas after setWrapSelectorWheel() until it receive a new MotionEvent;
6. no text hint at the center position;
7. cannot control NumberPicker to smoothly scroll to a certain item (position);
8. NumberPicker class in early version of some customized framework has bugs when changing maxValue and displayedValues.

Capabilities of NumberPickerView

1. the NumberPickerView’s viewport can show more than three items;
2. able to set the value of friction in java code, you can pick a new value smoothly by fling, in java code, you can use the code below to make friction be twice as former
   mNumberPickerView.setFriction(2 * ViewConfiguration.get(mContext).getScrollFriction());
3. items’ texts has animation between selected mode and normal mode, including Gradient textColor and Gradient textSize;
4. able to choose if use animation when changing displayedValues;
5. able to setWrapSelectorWheel() dynamically in java code or in xml;
6. able to set a hint text at the center position, default is empty; can change the hint text’s color and textSize;
7. able to scroll smoothly to a centain item (position);
8. support wrap_content mode,support item’s padding
9. has some other attibutes to refine UI
10. not respond onValueChanged() during scrolling
11. press the certain item, NumberPickerView will scroll to this item automatically
12. you can set if the onValueChanged callbacks invoked in main thread or in sub thread;
13. NumberPickerView has some same compatible fuctions and interfaces with NumberPicker, this makes it easier to change NumberPicker to NumberPickerView in project:

1.import to project

2.add a NumberPickerView in xml

3.control NumberPickerView in Java code 1)if the displayedValues in NumberPickerView will NOT change, you can set data by this way: (same as using NumberPicker)

2)if the displayedValues in NumberPickerView will change, you can set data by this way: (same as using NumberPicker)

OR use NumberPickerView’s method:
refreshByNewDisplayedValues(String[] display)
but make sure the minValue will NOT change before and after using this method, and display should not be null, and its length should be greater than 0.

4.NumberPickerView also have methods to scroll smoothly
public void smoothScrollToValue(int fromValue, int toValue, boolean needRespond)

the same point between this method and setValue(int) is you can set the current picked item dynamically, the difference is this method can make NumberPickerView scroll smoothly from fromValue to toValue by choosing short distance, the third argument needRespond is a boolean flag used to set if you want NumberPickerView invoke its onValueChanged callback when scrolling finished this time, because if several NumberPickerView s have interconnections, the early stopped NumberPickerView invoking callbacks will effect the latter stopped ones. So you can set this flag to be false to avoid invoking onValueChanged callback this time.

and you’d better not use this method in onCreate(Bundle savedInstanceState) , if have to do this, you can use in this way:

5.introduction of attibutes in xml

1.merge some pull requests
2.delete some dependence in library

1.refine the duration of position rewising
2.refine the interval of sending refreshing message
3.refine the sample’s UI

1.add attr app:npv_RespondChangeInMainThread=»true» to set if the onValueChanged callbacks invoked in mainThread or in subThread, default is true, in mainThread. set it false if you want to run onValueChanged in subThread. 2.update TimePickerActivity example, to give a How-To-Use of app:npv_RespondChangeInMainThread=»true» . 3.fix bug: when change displayed values, if it is scrolling, then the new displayed values’ position is not rewised

1.modify method stopScrolling , add scroll to current Y method before abortAnimation() is invoked
2.modify npv_RespondChangeOnDetached ‘s default value to false

1.refine code in onDetachToWindow() to respond callbacks or not, for reusable Dialog/PopupWindow .
If Dialog/PopupWindow is hiding meanwhile NumberPickerView is still scrolling, then we need it to stop scrolling and respond (or not) OnValueChange callbacks and change the previous picked value.
Add a new attr npv_RespondChangeOnDetached as a flag to set if respondding onValueChange callbacks, mainly for multi linked NumberPickerViews to correct other NumberPickerView’s position or value.
But I highly recommend every time showing a Dialog/PopupWindow please set certain data for NumberPickerView, and set npv_RespondChangeOnDetached false to avoid respondding onValueChange callbacks. See dialog in my GregorianLunarCalendar project.
These codes are not elegant, If you have any idea, please let me know, thank you.

1.add code in onDetachToWindow() to respond callbacks, for reusable Dialog/PopupWindow .

1.in method onAttachToWindow() , add code to judge if mHandlerThread has been quit() , this is to avoid of ‘can not correct position when show the same Dialog(or PopupWindow) twice ‘

1.modify some attrs’ name

1.fix bug : cannot scroll in ScrollView . Thanks Elektroktay’s and anjiao’s issues

1.how to generate scrolling animation

Scroller + VelocityTracker + onDraw(Canvas canvas)

2.how to correct position automatically when scrolling finished

Handler refresh current position

3.how to generate Gradient effection

by calculating the current coordinate, get the items which should be shown and the positions of each shown items, comparing the positions and center coordinate of NumberPickerView, get the current color and size of item’s text

how to CHANGE NumberPicker to NumberPickerView

just modify NumberPicker text into NumberPickerView in java code and xml, keep the methods and interfaces called by NumberPicker the same.

And something important

UI design inspired by Meizu company, a mobile phone Manufacturer in china.
A big thanks to google and meizu

Источник

Number picker wheel android

A simple customizable NumberPicker for Android.

Add NumberPicker component in your XML layout

Name	Type	Default
min	int	0
max	int	999999
value	int	1
unit	int	1
focusable	boolean	false
custom_layout	layout	@layout/number_picker_layout

if you want to customize your NumberPicker layout you can create your own.

IMPORTANT! This layout should contains at least 3 items with given Ids:

• Button (@+id/increment)
• Button (@+id/decrement)
• TextView (@+id/display)

Note: You can see an example layout in both sample and library modules.

Example XML layout:

Here is the list of methods with definitions.

Sets minimum value allowed

Gets minimum value

Sets maximum value allowed

Gets maximum value allowed

Sets unit value for increment/decrement operation

Gets unit value

Sets NumberPicker current value

Gets NumberPicker current value

setActionEnabled(ActionEnum action, boolean enabled)

Enables or disables Increment/Decrement buttons

Enables or disables NumberPicker editable via keyboard

NumberPicker will be incremented by defined unit value

NumberPicker will be incremented by given unit value

NumberPicker will be decremented by defined unit vale

NumberPicker will be decremented by given unit value

NumberPicker will be refreshed with already defined value

NumberPicker will lose the focus

Checks whether given value is acceptable or not

This is triggered when you try to set lower or higher than the given min/max limits

This is triggered when the NumberPicker is incremented or decremented.

Note: setValue method will not trigger this listener.

This is triggered when you click «done» button on keyboard after you edit current value.

Note: «done» button can be changed on xml so this listener should be overrided according to new IME option.

This is triggered when clearFocus() is called which helps to set new value when the focus lost

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A simple customizable NumberPicker plugin for Android

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