Review - II Kevin Gilmore Changes

theheapdump · theheapdump · commit 40f6fef100b7 · 2020-07-25T18:28:28.000Z
diff --git a/core-java-modules/core-java-jvm-2/src/main/java/com/baeldung/loadedclasslisting/Launcher.java b/core-java-modules/core-java-jvm-2/src/main/java/com/baeldung/loadedclasslisting/Launcher.java
@@ -1,48 +1,19 @@
 package com.baeldung.loadedclasslisting;
 
-import java.lang.reflect.Method;
 import java.util.Arrays;
 
-import com.baeldung.loadedclasslisting.ListLoadedClassesAgent.ClassLoaderType;
-import com.baeldung.loadedclasslisting.customLoader.ClassLoaderInfo;
-import com.baeldung.loadedclasslisting.customLoader.CustomClassLoader;
-
 public class Launcher {
 
-    private static ClassLoader customClassLoader;
-
     public static void main(String[] args) {
-        printClassesLoadedBy(ClassLoaderType.BOOTSTRAP);
-        printClassesLoadedBy(ClassLoaderType.SYSTEM);
-        printClassesLoadedBy(ClassLoaderType.EXTENSION);
-        printClassesLoadedBy(ClassLoaderType.CUSTOM);
+        printClassesLoadedBy("BOOTSTRAP");
+        printClassesLoadedBy("SYSTEM");
+        printClassesLoadedBy("EXTENSION");
     }
 
-    private static void printClassesLoadedBy(ClassLoaderType classLoaderType) {
-        Class<?>[] classes;
-        if (classLoaderType.equals(ClassLoaderType.CUSTOM)) {
-            customClassLoader = customClassLoading();
-            classes = ListLoadedClassesAgent.listLoadedClasses(customClassLoader);
-        } else {
-            classes = ListLoadedClassesAgent.listLoadedClasses(classLoaderType);
-        }
+    private static void printClassesLoadedBy(String classLoaderType) {
+        Class<?>[] classes = ListLoadedClassesAgent.listLoadedClasses(classLoaderType);
         Arrays.asList(classes)
             .forEach(clazz -> System.out.println(
               classLoaderType + " ClassLoader : " + clazz.getCanonicalName()));
     }
-    
-    private static CustomClassLoader customClassLoading() {
-        CustomClassLoader customClassLoader = new CustomClassLoader();
-        Class<?> c;
-        try {
-            c = customClassLoader.findClass(ClassLoaderInfo.class.getName());
-            Object ob = c.getDeclaredConstructor()
-                .newInstance();
-            Method md = c.getMethod("printClassLoaders");
-            md.invoke(ob);
-        } catch (Exception e) {
-            e.printStackTrace();
-        }
-        return customClassLoader;
-    }
 }
diff --git a/core-java-modules/core-java-jvm-2/src/main/java/com/baeldung/loadedclasslisting/ListLoadedClassesAgent.java b/core-java-modules/core-java-jvm-2/src/main/java/com/baeldung/loadedclasslisting/ListLoadedClassesAgent.java
@@ -4,17 +4,13 @@
 
 public class ListLoadedClassesAgent {
 
-    public enum ClassLoaderType {
-        SYSTEM, EXTENSION, BOOTSTRAP, CUSTOM , PLATFORM
-    }
-    
     private static Instrumentation instrumentation;
 
     public static void premain(String agentArgs, Instrumentation instrumentation) {
         ListLoadedClassesAgent.instrumentation = instrumentation;
     }
 
-    public static Class<?>[] listLoadedClasses(ClassLoaderType classLoaderType) {
+    public static Class<?>[] listLoadedClasses(String classLoaderType) {
         if (instrumentation == null) {
             throw new IllegalStateException(
               "ListLoadedClassesAgent is not initialized.");
@@ -23,24 +19,18 @@ public static Class<?>[] listLoadedClasses(ClassLoaderType classLoaderType) {
           getClassLoader(classLoaderType));
     }
 
-    public static Class<?>[] listLoadedClasses(ClassLoader classLoader) {
-        if (instrumentation == null) {
-            throw new IllegalStateException(
-              "ListLoadedClassesAgent is not initialized.");
-        }
-        return instrumentation.getInitiatedClasses(classLoader);
-    }
-
-    private static ClassLoader getClassLoader(ClassLoaderType classLoaderType) {
+    private static ClassLoader getClassLoader(String classLoaderType) {
         ClassLoader classLoader = null;
         switch (classLoaderType) {
-        case SYSTEM:
+        case "SYSTEM":
             classLoader = ClassLoader.getSystemClassLoader();
             break;
-        case EXTENSION:
+        case "EXTENSION":
             classLoader = ClassLoader.getSystemClassLoader().getParent();
             break;
-        case BOOTSTRAP:
+        // passing a null value to the Instrumentation : getInitiatedClasses method
+        // defaults to the bootstrap class loader
+        case "BOOTSTRAP":
             break;
         default:
             break;
