/* Hello.java - MBean implementation for the Hello World MBean. This class must implement all the Java methods declared in the HelloMBean interface, with the appropriate behavior for each one. */ package com.example.mbeans; public class Hello implements HelloMBean { public void sayHello() { System.out.println("hello, world"); } public int add(int x, int y) { return x + y; } /* Getter for the Name attribute. The pattern shown here is frequent: the getter returns a private field representing the attribute value. In our case, the attribute value never changes, but for other attributes it might change as the application runs. Consider an attribute representing statistics such as uptime or memory usage, for example. Being read-only just means that it can't be changed through the management interface. */ public String getName() { return this.name; } /* Getter for the CacheSize attribute. The pattern shown here is frequent: the getter returns a private field representing the attribute value, and the setter changes that field. */ public int getCacheSize() { return this.cacheSize; } /* Setter for the CacheSize attribute. To avoid problems with stale values in multithreaded situations, it is a good idea for setters to be synchronized. */ public synchronized void setCacheSize(int size) { this.cacheSize = size; /* In a real application, changing the attribute would typically have effects beyond just modifying the cacheSize field. For example, resizing the cache might mean discarding entries or allocating new ones. The logic for these effects would be here. */ System.out.println("Cache size now " + this.cacheSize); } private final String name = "Reginald"; private int cacheSize = DEFAULT_CACHE_SIZE; private static final int DEFAULT_CACHE_SIZE = 200; }