Log Analyzer

A Java command-line tool that analyzes log files and exports structured JSON summaries.

Features

• Smart Log Parsing - Automatically detects ERROR, WARNING, and INFO levels
• Frequency Analysis - Tracks most common errors
• JSON Export - Structured output for integration with monitoring tools
• JUnit Tests - 12 unit tests validating core functionality

Quick Start

Prerequisites

• Java 11+
• Maven 3.6+

Run

mvn clean package
java -jar target/log-analyzer-1.0-SNAPSHOT.jar

Example

Input: application.log

2025-01-18 ERROR Database connection failed
2025-01-18 INFO Application started
2025-01-18 WARNING Low memory detected
2025-01-18 ERROR Database connection failed

Output: log-summary_2025-01-18_10-30-00.json

{
  "timestamp": "2025-01-18",
  "fileAnalyzed": "application.log",
  "totalErrors": 2,
  "totalWarnings": 1,
  "totalInfo": 1,
  "mostFrequentErrors": [
    {
      "message": "ERROR Database connection failed",
      "count": 2
    }
  ]
}

Technologies

• Java 14
• Maven
• Jackson (JSON processing)
• JUnit 4

Project Structure

src/
├── main/java/loganalyzer/
│   ├── LogAnalyzer.java      # Core analysis logic
│   ├── JsonExporter.java     # JSON export
│   └── ProgramRunner.java    # Main application
└── test/java/loganalyzer/
    └── *Test.java             # Unit tests

Use Cases

• Automated error monitoring
• Integration with dashboards (Grafana, ELK)
• Historical error tracking