Initial commit

Author: simontom

.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

.idea/modules.xml

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+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention (RetentionPolicy.RUNTIME) // The annotation will be available during runtime
+@Target (ElementType.METHOD)         // This can just used in methods
+public @interface LogMethodCall {
+    Logger logLevel() default Logger.INFO;
+}

.idea/workspace.xml

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+public enum Logger {
+    INFO,
+    DEBUG
+}

LoggerTest.iml

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+public class Main {
+
+    public static void main(String[] args) {
+
+        Person p = new Person();
+        Utils.log(p, "foo");
+        p.foo(2);
+        Utils.log(p, "bar");
+        p.bar(3);
+
+    }
+
+}

src/LogMethodCall.java

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+public class Person {
+
+    // Will use the default log level (INFO)
+    @LogMethodCall
+    public void foo(int a) {
+        System.out.println("foo! " + a);
+    }
+
+    @LogMethodCall (logLevel = Logger.DEBUG)
+    public void bar(int b) {
+        System.out.println("bar! " + b);
+    }
+
+}

src/Logger.java

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+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+
+public class Utils {
+
+    public static void log(Object o, String methodName) {
+
+        // Gets the object class
+        Class klass = o.getClass();
+
+        // Iterate over its methods
+        for (Method m : klass.getMethods()) {
+
+            // Verify if the method is the wanted one
+            if (m.getName().equals(methodName)) {
+
+                // Yes, it is
+                // So, iterate over its annotations
+                for (Annotation a : m.getAnnotations()) {
+
+                    // Verify if it is a LogMethodCall annotation
+                    if (a instanceof LogMethodCall) {
+
+                        // Yes, it is
+                        // So, cast it
+                        LogMethodCall lmc = (LogMethodCall) a;
+
+                        // Verify the log level
+                        switch (lmc.logLevel()) {
+                            case INFO:
+                                System.out.println("performing info log for \"" + m.getName() + "\" method");
+                                break;
+                            case DEBUG:
+                                System.out.println("performing debug log for \"" + m.getName() + "\" method");
+                                break;
+                        }
+
+                    }
+                }
+
+                // Method encountered, so the loop can be break
+                break;
+
+            }
+
+        }
+
+    }
+
+}