在Java中找到调用方法和类的名称

Question

One of my colleagues decided we needed to print each class and method as they are executed so he promptly typed in the name of each method and class at the start of each method. This was not a little painful to me so I looked up on the web and came up with:

System.out.println(new Object(){}.getClass().getEnclosingClass().getSimpleName()+ " : "+
    new Object(){}.getClass().getEnclosingMethod().getName() +" [IN]");

This works swell. Except that now I have been informed that this is unsatisfactory because we are creating the Object for the sole purpose of finding the names and we should "Instead, simply use the class' .class property". Minor problem, I can't seem to get that to work.

Something else I found on the web was:

System.out.println(Thread.currentThread().getStackTrace()[1].getClassName()  + " : "+
    Thread.currentThread().getStackTrace()[1].getMethodName() +" [IN]");

which does what I need but somebody suggested it was SLOW, having to do a stack trace.

Does anybody have any good suggestions?

Answer 1

I noticed nobody answered the question, so I wrote something to time the two versions with a hard coded version as a control. These functions were called a million times on a 2998 MHz, SPARC-T4 with 64 bit, Java 1.8.0_91.

public String findFunc1()
{
    Class myCls=new Object(){}.getClass();

    String ret=myCls.getEnclosingClass().getSimpleName()+ " : "
              +myCls.getEnclosingMethod().getName()+ " [IN]";
    return ret;
}
public String findFunc2()
{
    StackTraceElement mySTE=Thread.currentThread().getStackTrace()[1];
    String ret=mySTE.getClassName() + " : "+ mySTE.getMethodName() + " [IN]";
    return ret;
}
public String findFunc3()
{
    String ret="TimeLog"+ " : "+ "findFunc3" + " [IN]";
    return ret;
}

They were called as follows:

public static void time1() {
    System.out.print("new Object version ");
    long startTime = System.currentTimeMillis();
    String ret;
    TimeLog prog=new TimeLog();

    for(int ii=0; ii<1*1000*1000; ii++) {
        ret=prog.findFunc1();
    }
    long endTime   = System.currentTimeMillis();
    long totalTime = endTime - startTime;
    System.out.println("Elapsed msec="+totalTime);
}

This gives:

new Object version Elapsed msec=13923
StackTrace version Elapsed msec=13459
Constant   version Elapsed msec=13

The two versions consume similar amounts of time but the hardcoded version is 1000 times faster.