Tutorial by Examples: w

Adding attributes to views

Custom views can also take custom attributes which can be used in Android layout resource files. To add attributes to your custom view you need to do the following: Define the name and type of your attributes: this is done inside res/values/attrs.xml (create it if necessary). The following file...

Android • Creating Custom Views

Renaming Variables While Destructuring

Destructuring allows us to refer to one key in an object, but declare it as a variable with a different name. The syntax looks like the key-value syntax for a normal JavaScript object. let user = { name: 'John Smith', id: 10, email: '[email protected]', }; let {user: userName, id: us...

JavaScript • Destructuring assignment

Quick "throwaway" macros

Add this to your vimrc: nnoremap Q @q To start recording the "throwaway" macro, use qq. To finish recording hit q (in normal mode for both). To execute the recorded macro, use Q. This is useful for macros that you need to repeat many times in a row but won't be likely to use again af...

vim • Tips and tricks to boost productivity

Hello World

This example creates a Polymer element named x-foo, whose template binds to a string property, named "message". The element's HTML is imported into the main document, which allows usage of <x-foo> tags in <body>. x-foo.html <dom-module id="x-foo"> <templ...

polymer • Getting started with polymer

Create a UIWebView instance

Swift let webview = UIWebView(frame: CGRect(x: 0, y: 0, width: 320, height: 480)) Objective-C UIWebView *webview = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)]; //Alternative way of defining frame for UIWebView UIWebView *webview = [[UIWebView alloc] init]; CGRect webviewFr...

iOS • UIWebView

throw, catch

Unlike many other programming languages, the throw and catch keywords are not related to exception handling in Ruby. In Ruby, throw and catch act a bit like labels in other languages. They are used to change the control flow, but are not related to a concept of "error" like Exceptions are...

Ruby Language • Control Flow

.where

The where method is available on any ActiveRecord model and allows querying the database for a set of records matching the given criteria. The where method accepts a hash where the keys correspond to the column names on the table that the model represents. As a simple example, we will use the foll...

Ruby on Rails • ActiveRecord Query Interface

.where with an array

The where method on any ActiveRecord model can be used to generate SQL of the form WHERE column_name IN (a, b, c, ...). This is achieved by passing an array as argument. As a simple example, we will use the following model: class Person < ActiveRecord::Base #attribute :first_name, :string ...

Ruby on Rails • ActiveRecord Query Interface

Pivoting with aggregating

import pandas as pd import numpy as np df = pd.DataFrame({'Name':['Mary', 'Jon','Lucy', 'Jane', 'Sue', 'Mary', 'Lucy'], 'Age':[35, 37, 40, 29, 31, 26, 28], 'City':['Boston', 'Chicago', 'Los Angeles', 'Chicago', 'Boston', 'Boston', 'Chicago'], ...

pandas • Reshaping and pivoting

Rebase down to the initial commit

Since Git 1.7.12 it is possible to rebase down to the root commit. The root commit is the first commit ever made in a repository, and normally cannot be edited. Use the following command: git rebase -i --root

Git • Rebasing

Writing your own contextmanager using generator syntax

It is also possible to write a context manager using generator syntax thanks to the contextlib.contextmanager decorator: import contextlib @contextlib.contextmanager def context_manager(num): print('Enter') yield num + 1 print('Exit') with context_manager(2) as cm: # the ...

Python Language • Context Managers (“with” Statement)

Removing all rows from the Employee table

TRUNCATE TABLE Employee; Using truncate table is often better then using DELETE TABLE as it ignores all the indexes and triggers and just removes everything. Delete table is a row based operation this means that each row is deleted. Truncate table is a data page operation the entire data page is...

SQL • TRUNCATE

Swift

Create Object Class: class Dog: Object { dynamic var name = "" dynamic var age = 0 } Assign Object's Values: let dog = Dog() dog.name = "Rex" dog.age = 1 Save Object: let realm = try! Realm() try! realm.write { realm.add(dog) } Reading Objects: ...

realm • Getting started with realm

How to write a good example?

Example is the main part of Documentation, it is thus important to provide clear and useful examples. Good examples are self-contained and succinct. Examples usually would have code for users to understand the topic better. Refer to the Help Center for more information.

Documentation • Examples

Different ways of instantiating an object of SharedPreferences

You can access SharedPreferences in several ways: Get the default SharedPreferences file: import android.preference.PreferenceManager; SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this); Get a specific SharedPreferences file: public static final String PREF_FILE_NAM...

Android • SharedPreferences

Rethrowing an exception within a catch block

Within a catch block the throw keyword can be used on its own, without specifying an exception value, to rethrow the exception which was just caught. Rethrowing an exception allows the original exception to continue up the exception handling chain, preserving its call stack or associated data: try...

.NET Framework • Exceptions

iOS XMPP Robbie Hanson Example with Openfire

SRXMPPDemo Download the example and all the classes here - https://github.com/SahebRoy92/SRXMPPDemo A demo on XMPP in Objective C, with various simple and complex features implemented in it. All the features of XMPP is done by "in band" xmpp functions. Few features this project contains...

iOS • iOS - Implementation of XMPP with Robbie Hanson framework

GridLayoutManager with dynamic span count

When creating a recyclerview with a gridlayout layout manager you have to specify the span count in the constructor. Span count refers to the number of columns. This is fairly clunky and doesn't take into account larger screen sizes or screen orientation. One approach is to create multiple layouts f...

Android • RecyclerView and LayoutManagers

Adding header view to recyclerview with gridlayout manager

To add a header to a recyclerview with a gridlayout, first the adapter needs to be told that the header view is the first position - rather than the standard cell used for the content. Next, the layout manager must be told that the first position should have a span equal to the *span count of the e...

Android • RecyclerView and LayoutManagers

Two-dimensional array

Using the Array::new constructor, your can initialize an array with a given size and a new array in each of its slots. The inner arrays can also be given a size and and initial value. For instance, to create a 3x4 array of zeros: array = Array.new(3) { Array.new(4) { 0 } } The array generated a...

Ruby Language • Arrays