How to get the caller class in Java [duplicate]

Question

I want to get the caller class of the method, i.e.

class foo{    bar();  } 

In the method bar, I need to get the class name foo, and I found this method:

Class clazz = sun.reflect.Reflection.getCallerClass(1); 

However, even though getCallerClass is public, when I try to call it Eclipse says:

Access restriction: The method getCallerClass() from the type Reflection is not accessible due to restriction on required library C:\Program Files\Java\jre7\lib\rt.jar

Are there any other choices?

Answer 1

You can generate a stack trace and use the informations in the StackTraceElements.

For example an utility class can return you the calling class name :

public class KDebug {     public static String getCallerClassName() {          StackTraceElement[] stElements = Thread.currentThread().getStackTrace();         for (int i=1; i<stElements.length; i++) {             StackTraceElement ste = stElements[i];             if (!ste.getClassName().equals(KDebug.class.getName()) && ste.getClassName().indexOf("java.lang.Thread")!=0) {                 return ste.getClassName();             }         }         return null;      } } 

If you call KDebug.getCallerClassName() from bar(), you'll get "foo".

Now supposing you want to know the class of the method calling bar (which is more interesting and maybe what you really wanted). You could use this method :

public static String getCallerCallerClassName() {      StackTraceElement[] stElements = Thread.currentThread().getStackTrace();     String callerClassName = null;     for (int i=1; i<stElements.length; i++) {         StackTraceElement ste = stElements[i];         if (!ste.getClassName().equals(KDebug.class.getName())&& ste.getClassName().indexOf("java.lang.Thread")!=0) {             if (callerClassName==null) {                 callerClassName = ste.getClassName();             } else if (!callerClassName.equals(ste.getClassName())) {                 return ste.getClassName();             }         }     }     return null;  } 

Is that for debugging ? If not, there may be a better solution to your problem.

Answer 2

StackTrace

This Highly depends on what you are looking for... But this should get the class and method that called this method within this object directly.

• index 0 = Thread
• index 1 = this
• index 2 = direct caller, can be self.
• index 3 ... n = classes and methods that called each other to get to the index 2 and below.

For Class/Method/File name:

Thread.currentThread().getStackTrace()[2].getClassName(); Thread.currentThread().getStackTrace()[2].getMethodName(); Thread.currentThread().getStackTrace()[2].getFileName(); 

For Class:

Class.forName(Thread.currentThread().getStackTrace()[2].getClassName()) 

FYI: Class.forName() throws a ClassNotFoundException which is NOT runtime. Youll need try catch.

Also, if you are looking to ignore the calls within the class itself, you have to add some looping with logic to check for that particular thing.

Something like... (I have not tested this piece of code so beware)

StackTraceElement[] stes = Thread.currentThread().getStackTrace(); for(int i=2;i<stes.length;i++)   if(!stes[i].getClassName().equals(this.getClass().getName()))     return stes[i].getClassName(); 

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StackWalker

StackWalker StackFrame

Note that this is not an extensive guide but an example of the possibility.

Prints the Class of each StackFrame (by grabbing the Class reference)

StackWalker.getInstance(Option.RETAIN_CLASS_REFERENCE)     .forEach(frame -> System.out.println(frame.getDeclaringClass())); 

Does the same thing but first collects the stream into a List. Just for demonstration purposes.

StackWalker.getInstance(Option.RETAIN_CLASS_REFERENCE)     .walk(stream -> stream.collect(Collectors.toList()))     .forEach(frame -> System.out.println(frame.getDeclaringClass()));