(Java using eclipse) currentTimeMillis()

Question

This is just a piece of what I am working at the moment I want to use currentTimeMillis() to print the time for an image to be loaded any reasons why it does not work?

package method;

import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Date;

 public class TracingInvocationHandler implements InvocationHandler {

private Object target;
private PrintWriter out;

public TracingInvocationHandler(Object target, PrintWriter out) {
    this.target = target;
    this.out = out;

}

@Override
public Object invoke(Object proxy, Method method, Object[] args)
        throws Throwable {
     long startTime = System.currentTimeMillis();
        Object result = null;
        out.println("Image " + method.getName() + " (...) entered.");
        result = method.invoke(target, args);
        out.println("Image " + method.getName() + " (...) returned.");
     long endTime = System.currentTimeMillis();
       System.out.printf(" [%s] %s Image %s took %d ms:",new Date().toString(), method.getName(),args[0], (endTime - startTime) + "ms");
    return result;

}

   public static Object createProxy(Object target, PrintWriter out) {
    Class<?> targetClass = target.getClass();
    ClassLoader currentClassLoader = targetClass.getClassLoader();
    Class<?>[] interfaces = targetClass.getInterfaces();
    InvocationHandler handler = new TracingInvocationHandler(target, out);
    return Proxy.newProxyInstance(currentClassLoader, interfaces, handler);
}

Answer 1

Remove + "ms" from (endTime - startTime) + "ms" . The corresponding format %d in the pattern expects a numeric object. (endTime - startTime) + "ms" produces a String .

You probably were receiving an exception. Next time you ask a question, please include it. This time you were lucky.

Answer 2

It's because you are casting a long primitive to float, I recommend you to use a variable where you cast: for example:

long totalTime = endTime - startTime;
String strTotalTime = String.valueOf(totalTime);
System.out.printf(" [%s] %s Image %s took %s ms:",
    new Date().toString(), method.getName(), args[0], strTotalTime);

Answer 3

Its invoked but I don't see you pass it to sysout, thats why its not visible. That is you're doing:

  long endTime = System.currentTimeMillis();
       System.out.printf(" [%s] %s Image %s took %d ms:",new Date().toString(),

instead of:

  long endTime = System.currentTimeMillis();
       System.out.printf(" [%s] %s Image %s took %d ms:",new Date(endTime).toString(),