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How to find in a method being called, which class & method invoked it? |
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Contributed by Howell
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Sunday, 04 June 2006 |
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At times (chain-of-responsibilty pattern, debugging etc), it is very handy to know in a method being called, which method invoked it. For example You may have an inheritance class hierarchy , which has got a method overridden by its subclasses. Let us look at some sample code to see how this can be achieved using StackTraceElement and Throwable
The base caller class:
public class CallerBase {
public void methodC1() {
new Callee().doSomething();
}
public static void main(String[] args) {
CallerBase caller = new CallerBase();
caller.methodC1();
caller = new CallerSub();
caller.methodC1();
}
}
The subclass of the caller class:
public class CallerSub extends CallerBase {
public void methodC1() {
new Callee().doSomething();
}
}
finally the important part of the code which determines who invoked it:
public class Callee {
public void doSomething() {
Throwable t = new Throwable();
StackTraceElement[] elements = t.getStackTrace();
String calleeMethod = elements[0].getMethodName();
String callerMethodName = elements[1].getMethodName();
String callerClassName = elements[1].getClassName();
System.out.println("CallerClassName=" + callerClassName + " , Caller method name: " + callerMethodName);
System.out.println("Callee method name: " + calleeMethod);
}
}
If you run the class CallerBase then the output is:
CallerClassName=CallerBase , Caller method name: methodC1
Callee method name: doSomething
CallerClassName=CallerSub , Caller method name: methodC1
Callee method name: doSomething
-- from the author of the book "Java/J2EE Job Interview Companion" at http://www.lulu.com/java-success |
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