Javaru

Javaru

Kotlin Coroutine Confidence: Placeholder message does not appear (pg 41)

Pg 41 states “Run the code, and you’ll see the placeholder message in a small window, just like last time.” for the code astronomy/v4/src/main/kotlin/com/example/astronomy/AstronomyApplication.kt. However when I run this, I get the a blank JFrame. The “Loading your image…” JLabel does not show.

This is in the B3 version of the book with the example code downloaded on 2025-04-19 at 14:42 EDT.

book-kotlin-coroutine-confidence pragprog

Marked As Solved

sam-cooper

sam-cooper

Author of Kotlin Coroutine Confidence

You’re absolutely right, the message is missing here for me too. It must have been working when I originally wrote and tested the code, so I’ll have to go back and see where the problem crept in.

To fix this one, we can add a call to window.revalidate() after adding the JLabel:

class ImageViewer : WindowAdapter() {
  override fun windowOpened(e: WindowEvent) {
    val window = e.window as JFrame
    window.add(JLabel("Loading your image…", JLabel.CENTER))
    window.revalidate()
    // TODO: download and display an image
  }
}

Let me know if this fixes the code for you. I’ll do a little more digging to make sure I understand how I missed the problem. Thank you so much for spotting the issue and letting me know about it!

Where Next?

Popular Pragmatic Bookshelf topics Top

belgoros
Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84: bundle exec sequel...
New
lirux
Hi Jamis, I think there’s an issue with a test on chapter 6. I own the ebook, version P1.0 Feb. 2019. This test doesn’t pass for me: ...
New
raul
Hi Travis! Thank you for the cool book! :slight_smile: I made a list of issues and thought I could post them chapter by chapter. I’m rev...
New
HarryDeveloper
Hi @venkats, It has been mentioned in the description of ‘Supervisory Job’ title that 2 things as mentioned below result in the same eff...
New
Chrichton
Dear Sophie. I tried to do the “Authorization” exercise and have two questions: When trying to plug in an email-service, I found the ...
New
leba0495
Hello! Thanks for the great book. I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
curtosis
Running mix deps.get in the sensor_hub directory fails with the following error: ** (Mix) No SSH public keys found in ~/.ssh. An ssh aut...
New
jskubick
I think I might have found a problem involving SwitchCompat, thumbTint, and trackTint. As entered, the SwitchCompat changes color to hol...
New
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
roadbike
From page 13: On Python 3.7, you can install the libraries with pip by running these commands inside a Python venv using Visual Studio ...
New

Other popular topics Top

AstonJ
A thread that every forum needs! Simply post a link to a track on YouTube (or SoundCloud or Vimeo amongst others!) on a separate line an...
New
AstonJ
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first: asdf plugin-upd...
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
AstonJ
Biggest jackpot ever apparently! :upside_down_face: I don’t (usually) gamble/play the lottery, but working on a program to predict the...
New
AstonJ
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
Help
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
AstonJ
If you want a quick and easy way to block any website on your Mac using Little Snitch simply… File > New Rule: And select Deny, O...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
mindriot
Ok, well here are some thoughts and opinions on some of the ergonomic keyboards I have, I guess like mini review of each that I use enoug...
New

Sub Categories: