output

How to debug RxJava Observable method calls/chains

As a brief note to self, when you need to debug a chain of RxJava Observable method calls, you can use the doOnNext method to log the current values or print them to STDOUT or STDERR with println. Here’s an example from RxJava For Android Developers, where the debug output is logged with the Android Log.d method:

How to write a Scala shell script that reads input from STDIN

As a quick note, if you need an example of how to write a Scala shell script that reads from STDIN (standard input) and writes to STDOUT (standard output), this code shows a solution:

#!/bin/sh
exec scala -savecompiled "$0" "$@"
!#

import scala.io.StdIn

var line = ""
while ({line = StdIn.readLine(); line != null}) {
    println(line)
}

An example of Android StrictMode output (with improper database access)

I was just working with an example of how to use Android’s new Room Persistence Library, and the example I was working with ran some of its code on the main Android thread, also known as its “UI thread.” I knew this was bad, but I wanted to start with someone’s example, and then figure out a good way to get the Room method calls to run on a background thread, such as using an AsyncTask. (The Android docs don’t specify a “best practice” for this atm.)

Sorting ‘ls’ command output by filesize alvin July 14, 2017 - 11:15am

I just noticed that some of the MySQL files on this website had grown very large, so I wanted to be able to list all of the files in the MySQL data directory and sort them by filesize, with the largest files shown at the end of the listing. This ls command did the trick, resulting in the output shown in the image:

ls -Slhr

The -S option is the key, telling the ls command to sort the file listing by size. The -h option tells ls to make the output human readable, and -r tells it to reverse the output, so in this case the largest files are shown at the end of the output.

Markdown comments syntax: Comments that won’t appear in generated output

Markdown FAQ: How do I create comments in Markdown? Especially comments that won’t appear in the generated output.

Part 1 of my answer is that technically there is no way — or at least no standard way — to create comments in Markdown documents, other than to use HTML comments like this: