Tutorial by Examples: en

Pitfall - String concatenation in a loop does not scale

Consider the following code as an illustration: public String joinWords(List<String> words) { String message = ""; for (String word : words) { message = message + " " + word; } return message; } Unfortunate this code is inefficient if the w...

Java Language • Java Pitfalls - Performance Issues

Do not launch Google Maps when the map is clicked (lite mode)

When a Google Map is displayed in lite mode clicking on a map will open the Google Maps application. To disable this functionality you must call setClickable(false) on the MapView, e.g.: final MapView mapView = (MapView)view.findViewById(R.id.map); mapView.setClickable(false);

Android • Google Maps API v2 for Android

Register beans only when a property or value is specified

A spring bean can be configured such that it will register only if it has a particular value or a specified property is met. To do so, implement Condition.matches to check the property/value: public class PropertyCondition implements Condition { @Override public boolean matches(ConditionC...

spring • Conditional bean registration in Spring

Working with stub entities

Say we have Products and Categorys in a many-to-many relationship: public class Product { public Product() { Categories = new HashSet<Category>(); } public int ProductId { get; set; } public string ProductName { get; set; } public virtual ICollection&lt...

Entity Framework • Optimization Techniques in EF

Wrap simple value into a promise using $q.when()

If all you need is to wrap the value into a promise, you don't need to use the long syntax like here: //OVERLY VERBOSE var defer; defer = $q.defer(); defer.resolve(['one', 'two']); return defer.promise; In this case you can just write: //BETTER return $q.when(['one', 'two']); $q.when ...

AngularJS • Angular promises with $q service

Key Binding Documentation

C-h k runs the function describe-key, which looks up the function mapped to the key strokes provided, and presents a description of the function which will be run when these keys are pressed. C-h c runs the function describe-key-briefly, which only displays the function name mapped to given key seq...

emacs • Help Within Emacs

Function Documentation

C-h f runs the function describe-function, which displays information on the usage and purpose of a given function. This is especially useful for functions that do not have a mapped key binding that can be used for documentation lookup via C-h k.

emacs • Help Within Emacs

Memory management rules when using manual reference counting.

These rules apply only if you use manual reference counting! You own any object you create By calling a method whose name begins with alloc, new, copy or mutableCopy. For example: NSObject *object1 = [[NSObject alloc] init]; NSObject *object2 = [NSObject new]; NSObject *object3 = [object2 ...

Objective-C Language • Memory Management

Managing Open Split Windows (Keyboard Shortcuts)

After you have opened a split window in vim (as demonstrated by many examples under this tag) then you will likely want to control windows quickly. Here is how to control split windows using keyboard shortcuts. Move to split Above/Below: Ctrl + w and k Ctrl + w and j Move to split Left/Right...

vim • Split windows

Sending HTML Email Using mail()

<?php $to = '[email protected]'; $subject = 'Sending an HTML email using mail() in PHP'; $message = '<html><body>This paragraph is bold.This text is italic.</body></html>'; $headers =...

PHP • Sending Email

Obtain class that satisfies generic parameter at runtime

Many unbound generic parameters, like those used in a static method, cannot be recovered at runtime (see Other Threads on Erasure). However there is a common strategy employed for accessing the type satisfying a generic parameter on a class at runtime. This allows for generic code that depends on ac...

Java Language • Generics

Denying access from IPs to files/directories

# Deny access to a directory from the IP 255.0.0.0 <Directory /path/to/directory> order allow,deny deny from 255.0.0.0 allow from all </Directory> # Deny access to a file from the IP 255.0.0.0 <FilesMatch "^\.ht"> order allow,deny deny fro...

Hypertext Access file • Denying Access

Using different (local) Nuget package sources using UI

It is common for company to set up it's own nuget server for distribution of packages across different teams. Go to Solution Explorer and click Right Mouse button then choose Manage NuGet Packages for Solution In window that opens click on Settings Click on + in top right corner the...

.NET Framework • NuGet packaging system

Dependency Injection using Ninject

The following example shows how to set up Dependency Injection using Ninject as an IoC container. First add a CustomModule class to your WebJob project, and add any dependency bindings there. public class CustomModule : NinjectModule { public override void Load() { Bind<IMyI...

azure-webjobs • Azure Webjobs SDK

Generate time series of random numbers then down sample

import pandas as pd import numpy as np import matplotlib.pyplot as plt # I want 7 days of 24 hours with 60 minutes each periods = 7 * 24 * 60 tidx = pd.date_range('2016-07-01', periods=periods, freq='T') # ^ ^ # | ...

pandas • Grouping Time Series Data

Fundamental type traits

C++11 There are a number of different type traits that compare more general types. Is Integral: Evaluates as true for all integer types int, char, long, unsigned int etc. std::cout << std::is_integral<int>::value << "\n"; // Prints true. std::cout << std::is_in...

C++ • Type Traits

Check for the existence of fields on JSON

Sometimes it's useful to check if a field is present or absent on your JSON to avoid some JSONException on your code. To achieve that, use the JSONObject#has(String) or the method, like on the following example: Sample JSON { "name":"James" } Java code String jsonStr...

Android • JSON in Android with org.json

Use StringBuilder to create string from a large number of records

public string GetCustomerNamesCsv() { List<CustomerData> customerDataRecords = GetCustomerData(); // Returns a large number of records, say, 10000+ StringBuilder customerNamesCsv = new StringBuilder(); foreach (CustomerData record in customerDataRecords) { custom...

C# Language • StringBuilder

Identifiers & Identifier Names

With regards to reserved words there is a small distinctions between the "Identifiers" used for the likes of variable or function names and the "Identifier Names" allowed as properties of composite data types. For example the following will result in an illegal syntax error: va...

JavaScript • Reserved Keywords

Generate RSA Key

In order to generate an RSA key, an EVP_PKEY must first be allocated with EVP_PKEY_new: EVP_PKEY *pkey; pkey = EVP_PKEY_new(); An exponent for the key is also needed, which will require allocating a BIGNUM with BN_new and then assigning with BN_set_word: BIGNUM *bn; bn = BN_new(); BN_set_wor...

openssl • Keys