Tutorial by Examples: id

DBContract.java //Define the tables and columns of your local database public final class DBContract { /*Content Authority its a name for the content provider, is convenient to use the package app name to be unique on the device */ public static final String CONTENT_AUTHORITY =...
A word of caution: AsyncTask has many gotcha's apart from the memory leak described here. So be careful with this API, or avoid it altogether if you don't fully understand the implications. There are many alternatives (Thread, EventBus, RxAndroid, etc). One common mistake with AsyncTask is to c...
It is very rare that you'll ever want to use Select or Activate in your code, but some Excel methods do require a worksheet or workbook to be activated before they'll work as expected. If you're just starting to learn VBA, you'll often be suggested to record your actions using the macro recorder, t...
See this Q&A question if you don't know what race conditions are. The following code may be subject to race conditions : article = Article.objects.get(pk=69) article.views_count += 1 article.save() If views_count is equal to 1337, this will result in such query: UPDATE app_article SET vi...
If you have no type at all, commonly used for functions that do not return anything: function log(): void { console.log('I return nothing'); } void types Can only be assigned null or undefined.
A GridLayout is a layout manager which places components inside a grid with equal cell sizes. You can set the number of rows, columns, the horizontal gap and the vertical gap using the following methods: setRows(int rows) setColumns(int columns) setHgap(int hgap) setVgap(int vgap) or you ca...
This is a minimalist Hello World example that uses only the most basic Android tools. Requirements and assumptions Oracle JDK 1.7 or later Android SDK Tools (just the command line tools) This example assumes Linux. You may have to adjust the syntax for your own platform. Setting up the And...
The most important AppWidgetProvider callback is onUpdate(). It is called everytime an appwidget is added. public class ExampleAppWidgetProvider extends AppWidgetProvider { public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) { final int N = a...
It's a regular pattern in design these days to vertically align call to actions inside its containing cards like this: This can be achieved using a special trick with flexbox HTML <div class="cards"> <div class="card"> <p>Lorem ipsum Magna proident ...
Validates a value is a valid IP address var_dump(filter_var('185.158.24.24', FILTER_VALIDATE_IP)); var_dump(filter_var('2001:0db8:0a0b:12f0:0000:0000:0000:0001', FILTER_VALIDATE_IP)); var_dump(filter_var('192.168.0.1', FILTER_VALIDATE_IP)); var_dump(filter_var('127.0.0.1', FILTER_VALIDATE_IP)); ...
Screen shot: Option 1 (pure adb) The shell adb command allows us to execute commands using a device's built-in shell. The screencap shell command captures the content currently visible on a device and saves it into a given image file, e.g. /sdcard/screen.png: adb shell screencap /sdcard/screen.png...
The reason you do not have to override Awake, Start, Update and other method is because they are not virtual methods defined in a base class. The first time your script gets accessed, the scripting runtime looks through the script to see if some methods are defined. If they are, that information is...
To forbid null values in your table columns, add the :null parameter to your migration, like this: class AddPriceToProducts < ActiveRecord::Migration def change add_column :products, :float, null: false end end
1) Form Request Validation You may create a "form request" which can hold the authorization logic, validation rules, and error messages for a particular request in your application. The make:request Artisan CLI command generates the class and places it in the app/Http/Requests director...
public class MainApplication extends Application { private static Context context; //application context private Handler mainThreadHandler; private Toast toast; public Handler getMainThreadHandler() { if (mainThreadHandler == null) { mainThreadHand...
Changing some CSS attribute will trigger the browser to synchronously calculate the style and layout, which is a bad thing when you need to animate at 60fps. DON'T Animate with left and top trigger layout. #box { left: 0; top: 0; transition: left 0.5s, top 0.5s; position: absolute; ...
The .indexOf method returns the index of a substring inside another string (if exists, or -1 if otherwise) 'Hellow World'.indexOf('Wor'); // 7 .indexOf also accepts an additional numeric argument that indicates on what index should the function start looking "harr dee harr dee harr&quot...
library(tidyr) ## example data set.seed(123) df <- data.frame( name = rep(c("firstName", "secondName"), each=4), numbers = rep(1:4, 2), value = rnorm(8) ) df # name numbers value # 1 firstName 1 -0.56047565 # 2 firstName 2 -0.2301...
Sometimes it is necessary or desirable to place the legend outside the plot. The following code shows how to do it. import matplotlib.pylab as plt fig, ax = plt.subplots(1, 1, figsize=(10,6)) # make the figure with the size 10 x 6 inches fig.suptitle('Example of a Legend Being Placed Outside of...
ASDF provides the package ASDF-USER for developers to define their packages in.

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