Prints this throwable and its backtrace to the standard
error stream. This method prints a stack trace for this
Throwable object on the error output stream that
is the value of the field System.err. The first
line of output contains the result of the
ChainedError.toString() method for this object. Remaining lines represent data
previously recorded by the method
ChainedError.fillInStackTrace() . The format of this information depends on
the implementation, but the following example may be regarded
as typical:
java.lang.NullPointerException
at MyClass.mash(MyClass.java:9)
at MyClass.crunch(MyClass.java:6)
at MyClass.main(MyClass.java:3)
This example was produced by running the program:
class MyClass {
public static void main(String[] args) {
crunch(null);
}
static void crunch(int[] a) {
mash(a);
}
static void mash(int[] b) {
System.out.println(b[0]);
}
}
The backtrace for a throwable with an initialized, non-null
cause should generally include the backtrace for the cause.
The format of this information depends on the implementation,
but the following example may be regarded as typical:
HighLevelException: MidLevelException: LowLevelException
at Junk.a(Junk.java:13)
at Junk.main(Junk.java:4)
Caused by: MidLevelException: LowLevelException
at Junk.c(Junk.java:23)
at Junk.b(Junk.java:17)
at Junk.a(Junk.java:11)
... 1 more
Caused by: LowLevelException
at Junk.e(Junk.java:30)
at Junk.d(Junk.java:27)
at Junk.c(Junk.java:21)
... 3 more
Note the presence of lines containing the characters
"...". These lines indicate that the remainder of the
stack trace for this exception matches the indicated number of
frames from the bottom of the stack trace of the exception that
was caused by this exception (the "enclosing" exception). This
shorthand can greatly reduce the length of the output in the
common case where a wrapped exception is thrown from same
method as the "causative exception" is caught. The above
example was produced by running the program:
public class Junk {
public static void main(String args[]) {
try {
a();
} catch(HighLevelException e) {
e.printStackTrace();
}
}
static void a() throws HighLevelException {
try {
b();
} catch(MidLevelException e) {
throw new HighLevelException(e);
}
}
static void b() throws MidLevelException {
c();
}
static void c() throws MidLevelException {
try {
d();
} catch(LowLevelException e) {
throw new MidLevelException(e);
}
}
static void d() throws LowLevelException {
e();
}
static void e() throws LowLevelException {
throw new LowLevelException();
}
}
class HighLevelException extends Exception {
HighLevelException(Throwable cause) { super(cause); }
}
class MidLevelException extends Exception {
MidLevelException(Throwable cause) { super(cause); }
}
class LowLevelException extends Exception {
}
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