Implementation
Implement a log analyzer: open file, read lines, count errors, and summarize results.
Implementation is a free Java Academy lesson on CoddyKit. This is lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, and your progress syncs across the web and the CoddyKit app. The Java Academy course includes 3 lessons in total.
Intro
Implementation means coding the design: open log files, process lines, and produce summaries.
File reading setup
We use Files.newBufferedReader to read logs line by line. Each line can then be parsed for keywords.
Code: read lines
This code prints each log line. Next, we add parsing to count errors.
import java.nio.file.*;import java.io.*;
public class Main {
public static void main(String[] args) {
Path log = Paths.get("app.log");
try (BufferedReader br = Files.newBufferedReader(log)) {
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Parsing logic
We check if a line contains keywords like ERROR. Counting them gives us a quick error summary.
Code: count errors
This code counts how many lines contain ERROR.
import java.nio.file.*;import java.io.*;
public class Main {
public static void main(String[] args) {
Path log = Paths.get("app.log");
int errors = 0;
try (BufferedReader br = Files.newBufferedReader(log)) {
String line;
while ((line = br.readLine()) != null) {
if (line.contains("ERROR")) {
errors++;
}
}
System.out.println("Total errors: " + errors);
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Code: summarize
This summarizes both errors and warnings. Summaries give useful quick insights.
import java.nio.file.*;import java.io.*;
public class Main {
public static void main(String[] args) {
Path log = Paths.get("app.log");
int errors = 0, warnings = 0;
try (BufferedReader br = Files.newBufferedReader(log)) {
String line;
while ((line = br.readLine()) != null) {
if (line.contains("ERROR")) errors++;
if (line.contains("WARN")) warnings++;
}
System.out.println("Errors: " + errors);
System.out.println("Warnings: " + warnings);
} catch (IOException e) {
System.out.println("Error: " + e.getMessage());
}
}
}
Implementation check
Quick check: What is the main goal of the implementation step?
Recap
Recap: Implementation turns design into code. We read log lines, parse them, and summarize errors/warnings.
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Frequently Asked Questions
Is the “Implementation” lesson free?
Yes — the full text of “Implementation” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO. The Java Academy course includes 3 lessons in total.
What will I learn in “Implementation”?
Implement a log analyzer: open file, read lines, count errors, and summarize results. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Java Academy?
No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 3.
How long does the “Implementation” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Java Academy lesson?
Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.