I want to get error message using java when exception are generated.
now I have java code with following scenario:
method first(){
try{
second();
}catch(Exception e){
System.out.println("Error:> "+e)
}
}
method second(){
try{
my code
}catch(Exception e){
throw new Exception("Exception generate in second method",e);
}
}
now when the first method execute then I get only "Exception generate in second method" message but there is some other message printed on console by java so how to get that console error message.
Note: I have already try with e.getMessage(); and e.printStackTrace();
Every exception has a cause that you can get with getCause()
. You can go recursively down them until you get to the root cause. Here is your example with a utility that dumps the exception with all its causes like the console does.
private void first() {
try {
second();
} catch (Exception ex) {
Log.e("CATCH", getExceptionDump(ex));
}
}
private void second() {
try {
throw new UnsupportedOperationException("We don't do this.");
} catch (Exception ex) {
throw new RuntimeException("Exception in second()", ex);
}
}
private String getExceptionDump(Exception ex) {
StringBuilder result = new StringBuilder();
for (Throwable cause = ex; cause != null; cause = cause.getCause()) {
if (result.length() > 0)
result.append("Caused by: ");
result.append(cause.getClass().getName());
result.append(": ");
result.append(cause.getMessage());
result.append("\n");
for (StackTraceElement element: cause.getStackTrace()) {
result.append("\tat ");
result.append(element.getMethodName());
result.append("(");
result.append(element.getFileName());
result.append(":");
result.append(element.getLineNumber());
result.append(")\n");
}
}
return result.toString();
}
The message in the Exception constructor argument is not printed in the exception detail. You can simply use this code to print the message :
method first(){
try{
second();
}catch(Exception e){
System.out.println("Error:> "+e.getMessage())
}
}
Hope this solves your problem
Why you cannot use print stack trace ?
Because A throwable contains a snapshot of the execution stack of its thread at the time it was created.
(see Throwable )
It implies that, if you want to print the stack trace you need to use the printStackTrace()
method BUT in your second method !
method second(){
try {
my code
} catch(Exception e) {
e.printStackTrace();
throw new Exception("Exception generate in second method",e);
}
}
Or using a the tricky method setStackTrace
and using the printStackTrace()
in first
method second(){
try {
my code
} catch(Exception e) {
Exception ex = new Exception("Exception generate in second method",e);
ex.setStackTrace(e);
throw ex;
}
}
method first(){
try {
second();
} catch(Exception e) {
e.printStackTrace();
}
}
You can print the cause of the exception you get. Try this:
method first(){
try{
second();
}catch(Exception e){
System.out.println("Error:> "+e);
if (e.getCause() != null) {
System.out.println("Cause:> " + e.getCause());
}
}
}
I believe this is the console message you want to achieve:
Error:> java.lang.Exception: Exception generate in second method
Try this code, when the catch block of the second method throws an exception the second method should declare it as throws or put a nested try catch within the catch block.
The exception is propagated to the first() method which is handled by its catch block.
public class Test {
public void first() {
try {
second();
} catch (Exception e) {
System.out.println("Error:> " + e);
}
}
public void second() throws Exception {
try {
throw new Exception();
} catch (Exception e) {
throw new Exception("Exception generate in second method", e);
}
}
public static void main(String ars[]) {
Test test = new Test();
test.first();
}
}
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