Takes me back to simpler days when Java was THE language to learn and book like this was interesting. It seems the author took each day in the book as an inspiration for a blog post, which gives it value beyond the book itself.
I taught students in Java and Python and noticed that Python is actually harder. Things you don't even notice, like breathing, make a lot of confusion for newcomers.
The biggest one is types -- students think in terms of meaning, not types, e.g. "this my variable contains first name", but they don't realize it's a string. Or "this is products in checkout cart", but the variable is an integer, so it's products count, not a list of product. Once students get idea of getting an item of a collection and getting a field of that item, while watching every type along the way -- that's a major breakthrough during learning.
The easiest to learn would be a language where you have to define all variable types on top, like Pascal (a language created specifically for learning). But Java is still better than Python, as it doesn't even run wit messed types.
Unless you write everything from scratch, you are forced to deal with 20 years of bad design. I really wish people would just stop beating this dead horse.
What exactly is the intuition behind taking something inherently linear like a sequence of 100 days and presenting it as a graph with no information given about the rationale or reasoning behind the edges.
I completed 100 Days of Java and ended up and it took me roughly 5 years.
Made an interactive map/index of the posts, linked by related topics. I made it to make the series easier to browse by concept instead of only by day number.
the source is mostly the content tags in each blog posts. https://mohibulsblog.netlify.app/blog/ each post have some content tags. graph is based on that.
I personally am not sure what's the point of this, when the graph seems like doesn't give any real information + doesn't even work on mobile (no hover), but congrats on finishing up the series!
I'd be a bit skeptical of the result given the benchmark program:
import java.util.ArrayList;
import java.util.List;
class Day06 {
public static void main(String args[]) {
List<String> fileTypeList = new ArrayList<>();
for (int i = 0; i < 1000000; i++) {
fileTypeList.add("fileType");
}
long beforeForLoop = System.currentTimeMillis();
for (int i = 0; i < fileTypeList.size(); i++) {
fileTypeList.get(i);
}
long afterForLoop = System.currentTimeMillis();
System.out.println("Time took in millis for for " + (afterForLoop - beforeForLoop));
long beforeForeachLoop = System.currentTimeMillis();
for (String s : fileTypeList) {
}
long afterForeachLoop = System.currentTimeMillis();
System.out.println("Time took in millis for foreach " + (afterForeachLoop - beforeForeachLoop));
}
}
Empty loops and no warmup (at a minimum!) make for a somewhat suboptimal benchmark, to say the least. To be honest I'm surprised the JIT didn't eliminate the loops altogether.
If you want proper results you probably want to use the Java Microbenchmark Harness [0]. You'd probably want some actual data/work as well so the JIT doesn't overspecialize on the benchmark.
Edit: Halfheartedly tried to adapt the LinkedIn benchmark to JMH. Still not a great benchmark and I'm rusty so I wouldn't be surprised if I messed something up, but it's hopefully better the original:
package org.sample;
import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
@State(Scope.Thread)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class MyBenchmark {
List<String> fileTypeList = new ArrayList<>() {{
for (int i = 0; i < 1000000; i++) {
this.add("fileType");
}
}};
@Benchmark
public void baseline() {
}
@Benchmark
public int measureFor() {
int result = 0;
for (int i = 0; i < fileTypeList.size(); i++) {
result += (int)fileTypeList.get(i).charAt(0);
}
return result;
}
@Benchmark
public int measureForEach() {
int result = 0;
for (String s : fileTypeList) {
result += (int)s.charAt(0);
}
return result;
}
public static void main(String[] args) throws RunnerException {
Options opt = new OptionsBuilder()
.include(MyBenchmark.class.getSimpleName())
.build();
new Runner(opt).run();
}
}
And the result summary (run on Ubuntu via WSL2):
# JMH version: 1.37
# VM version: JDK 21.0.10, OpenJDK 64-Bit Server VM, 21.0.10+7-Ubuntu-124.04
# VM invoker: /usr/lib/jvm/java-21-openjdk-amd64/bin/java
# VM options: <none>
# Blackhole mode: compiler (auto-detected, use -Djmh.blackhole.autoDetect=false to disable)
# Warmup: 5 iterations, 10 s each
# Measurement: 5 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
Result "org.sample.MyBenchmark.baseline":
0.254 ±(99.9%) 0.022 ns/op [Average]
(min, avg, max) = (0.247, 0.254, 0.262), stdev = 0.006
CI (99.9%): [0.232, 0.276] (assumes normal distribution)
Result "org.sample.MyBenchmark.measureFor":
693178.390 ±(99.9%) 60793.583 ns/op [Average]
(min, avg, max) = (676266.480, 693178.390, 718114.554), stdev = 15787.901
CI (99.9%): [632384.806, 753971.973] (assumes normal distribution)
Result "org.sample.MyBenchmark.measureForEach":
693756.240 ±(99.9%) 7549.769 ns/op [Average]
(min, avg, max) = (691685.231, 693756.240, 696573.323), stdev = 1960.651
CI (99.9%): [686206.470, 701306.009] (assumes normal distribution)
Doesn't look like a significant difference to me, though obviously the benchmark quality leaves something to be desired.
[0]: https://github.com/openjdk/jmh
for each is syntactic sugar for a while loop with an iterator. It will always be slower than the classic for index loop over the same collection/array.
This looks interesting, I worked with Java some time ago, but haven't touched it for some time. I guess since the graph is really not that intuitive this really describes how complicated can be learning Java!
Learning java is not that hard. I really love this language with all its quirks. so i guess i will be little biased here but its my fault not to represent the information in such a way that it can be more intuitive.
> Day 1: Comparing/ checking equality against multiple Strings.
Just use Apache Commons Lang Strings.CS.equalsAny . If not, List.of or Set.of (if N could be big) should be the best options. Streams are better when you chain many operations.
Takes me back to simpler days when Java was THE language to learn and book like this was interesting. It seems the author took each day in the book as an inspiration for a blog post, which gives it value beyond the book itself.
I taught students in Java and Python and noticed that Python is actually harder. Things you don't even notice, like breathing, make a lot of confusion for newcomers.
The biggest one is types -- students think in terms of meaning, not types, e.g. "this my variable contains first name", but they don't realize it's a string. Or "this is products in checkout cart", but the variable is an integer, so it's products count, not a list of product. Once students get idea of getting an item of a collection and getting a field of that item, while watching every type along the way -- that's a major breakthrough during learning.
The easiest to learn would be a language where you have to define all variable types on top, like Pascal (a language created specifically for learning). But Java is still better than Python, as it doesn't even run wit messed types.
Java would be fine if it and it's community wouldn't force OOP and GOF patterns everywhere.
2003 called and wants its arguments against Java back.
Modern Java can be OOP, functional or procedural where useful. GoF patterns were never enforced by the language.
I'd say GoF patterns were pretty enforced by the language if you include the standard libraries.
Or maybe that's even a bit rude to GoF. Some OO patterns - pretty questionable ones - were pushed pretty hard especially in Java EE.
Does the name of the class inside the file still break the wall and force what the name of the file needs to be?
Unless you write everything from scratch, you are forced to deal with 20 years of bad design. I really wish people would just stop beating this dead horse.
What exactly is the intuition behind taking something inherently linear like a sequence of 100 days and presenting it as a graph with no information given about the rationale or reasoning behind the edges.
Think of each day as a lesson, and then it makes more sense. E.g. Lesson 49 was useful for understanding Lessons 50 and 65.
It's 100 days of Java, not 100 days of Visual Information Architecture.
I completed 100 Days of Java and ended up and it took me roughly 5 years.
Made an interactive map/index of the posts, linked by related topics. I made it to make the series easier to browse by concept instead of only by day number.
Nice work! I appreciate the topic and search filters too.
I looked around, but can't find the source information this was created off of -- where are the questions/topics for the 100 days listed?
the source is mostly the content tags in each blog posts. https://mohibulsblog.netlify.app/blog/ each post have some content tags. graph is based on that.
Your category names aren't rendering the "&" correctly as "&", might want to look into that (Chrome 147.0.7727.138, Windows)
This website is very confusing.
would love to know how can i improve if you can give some feedback like which part is confusing.
You should try rendering the graph in 3js. It’s pretty easy and so so beautiful.
Toto.tech has a decent example. You have flight controls with wasd + mouse
will try it this weekend. Thanks for the suggestion
I personally am not sure what's the point of this, when the graph seems like doesn't give any real information + doesn't even work on mobile (no hover), but congrats on finishing up the series!
sorry as UI was not optimized enough for mobile but my intention was to show the adventure of writing and learning more about java
Wait, foreach is slower then for loop? I did not know this.
I'd be a bit skeptical of the result given the benchmark program:
Empty loops and no warmup (at a minimum!) make for a somewhat suboptimal benchmark, to say the least. To be honest I'm surprised the JIT didn't eliminate the loops altogether.If you want proper results you probably want to use the Java Microbenchmark Harness [0]. You'd probably want some actual data/work as well so the JIT doesn't overspecialize on the benchmark.
Edit: Halfheartedly tried to adapt the LinkedIn benchmark to JMH. Still not a great benchmark and I'm rusty so I wouldn't be surprised if I messed something up, but it's hopefully better the original:
And the result summary (run on Ubuntu via WSL2): Doesn't look like a significant difference to me, though obviously the benchmark quality leaves something to be desired. [0]: https://github.com/openjdk/jmhfor each is syntactic sugar for a while loop with an iterator. It will always be slower than the classic for index loop over the same collection/array.
This looks interesting, I worked with Java some time ago, but haven't touched it for some time. I guess since the graph is really not that intuitive this really describes how complicated can be learning Java!
Learning java is not that hard. I really love this language with all its quirks. so i guess i will be little biased here but its my fault not to represent the information in such a way that it can be more intuitive.
As a Java Developer that has been coding since Java 1.2.2; it depends on the quirks :D
To name 2:
https://devdocs.io/openjdk~21/java.base/java/util/gregorianc...
https://devdocs.io/openjdk~21/java.base/java/net/url#equals(...
> Day 1: Comparing/ checking equality against multiple Strings.
Just use Apache Commons Lang Strings.CS.equalsAny . If not, List.of or Set.of (if N could be big) should be the best options. Streams are better when you chain many operations.