# Java Performance Optimization: Best Practices for 2025 Performance optimization is crucial for Java applications, especially in enterprise environments where efficiency directly impacts user experience and operational costs. ## JVM Performance Tuning ### Garbage Collection Optimization Choose the right GC algorithm for your use case: ```bash # G1GC for low-latency applications -XX:+UseG1GC -XX:MaxGCPauseMillis=200 # ZGC for ultra-low latency -XX:+UseZGC # Parallel GC for throughput -XX:+UseParallelGC ``` ### Memory Management Optimize heap and non-heap memory: ```bash # Heap size configuration -Xms2g -Xmx4g # Metaspace configuration -XX:MetaspaceSize=256m -XX:MaxMetaspaceSize=512m ``` ## Code-Level Optimizations ### 1. Use Efficient Data Structures ```java // Use ArrayList for frequent access List<String> list = new ArrayList<>(); // Use LinkedList for frequent insertions/deletions List<String> linkedList = new LinkedList<>(); // Use HashMap for key-value lookups Map<String, Object> map = new HashMap<>(); ``` ### 2. Optimize String Operations ```java // Use StringBuilder for multiple concatenations StringBuilder sb = new StringBuilder(); for (String item : items) { sb.append(item).append(", "); } String result = sb.toString(); ``` ### 3. Leverage Streams Wisely ```java // Parallel streams for CPU-intensive operations List<Integer> result = numbers.parallelStream() .filter(n -> n > 100) .map(n -> n * 2) .collect(Collectors.toList()); ``` ## Profiling and Monitoring ### 1. JProfiler Integration ```java // Enable JFR for production monitoring -XX:+FlightRecorder -XX:StartFlightRecording=duration=60s,filename=app.jfr ``` ### 2. Application Metrics ```java @Component public class PerformanceMetrics { private final MeterRegistry meterRegistry; @Timed(name = "user.service.time") public User findUser(Long id) { return userRepository.findById(id); } } ``` Performance optimization is an ongoing process that requires continuous monitoring and tuning based on application behavior and requirements.