如何循环通过 Exception getCause()来查找带有详细信息的根原因

Are you asking for something like this?

Throwable cause = originalException;
while(cause.getCause() != null && cause.getCause() != cause) {
cause = cause.getCause();
}

or am I missing something?

The Apache ExceptionUtils provide the following method:

Throwable getRootCause(Throwable throwable)

as well as

String getRootCauseMessage(Throwable th)

} catch (Exception ex) {
while (ex.getCause() != null)
ex = ex.getCause();
System.out.println("Root cause is " + ex.getMessage());
}

Were you expecting something more complicated?

In APACHE; the implementation is like below.

The highlight is list.contains(throwable) == false

public static Throwable getRootCause(final Throwable throwable) {
final List<Throwable> list = getThrowableList(throwable);
return list.size() < 2 ? null : (Throwable)list.get(list.size() - 1);
}


public static List<Throwable> getThrowableList(Throwable throwable) {
final List<Throwable> list = new ArrayList<Throwable>();
while (throwable != null && list.contains(throwable) == false) {
list.add(throwable);
throwable = ExceptionUtils.getCause(throwable);
}
return list;
}

I normally use the implementation below instead of Apache's one.

Besides its complexity, Apache's implementation returns null when no cause is found, which force me to perform an additional check for null.

Normally when looking for an exception's root/cause I already have a non-null exception to start with, which is for all intended proposes is the cause of the failure at hand, if a deeper cause can't be found.

Throwable getCause(Throwable e) {
Throwable cause = null;
Throwable result = e;


while(null != (cause = result.getCause())  && (result != cause) ) {
result = cause;
}
return result;
}

Using java 8 Stream API, this can be achieved by:

Optional<Throwable> rootCause = Stream.iterate(exception, Throwable::getCause)
.filter(element -> element.getCause() == null)
.findFirst();

Note that this code is not immune to exception cause loops and therefore should be avoided in production.

Guava's Throwables provides the following methods:

Throwable getRootCause(Throwable throwable)

as well as

String getStackTraceAsString(Throwable throwable)

Try this, you can put this function in a kind of Util class:

public static Throwable getRootException(Throwable exception){
Throwable rootException=exception;
while(rootException.getCause()!=null){
rootException = rootException.getCause();
}
return rootException;
}

Example of usage :

catch(MyException e){
System.out.println(getRootException(e).getLocalizedMessage());
}

Source : How to get the root exception of any exception

Recursively:

public static Throwable getRootCause(Throwable e) {
if (e.getCause() == null) return e;
return getRootCause(e.getCause());
}