How to display a detailed error message using try{ }catch(){ } blocks

Question

Suppose in your program you might get an IndexOutOfBoundsException. i am handling it in the following way:

try{
//throws an IndexOutOfBoundsException during runtime
}catch(IndexOutOfBoundsException ex){
System.err.println(ex);
}

This will only display java.lang.IndexOutOfBoundsException. But I would like to display a detailed error message (which won't terminate the program), like the one that java gives us (lineNumber, fileName, etc) when we do not handle the error and thus terminates the program.

use ex.printStackTrace() – RAZ_Muh_Taz Oct 31 '16 at 20:40 — RAZ_Muh_Taz, Oct 31 '16 at 20:40

score 3 · Answer 1 · answered Oct 31 '16 at 20:42

3

Use ex.printStackTrace() method to print the exception:

try {
    int[] x = new int[1];
    x[2] = 5;
} catch (IndexOutOfBoundsException ex) {
    ex.printStackTrace();
}
System.err.println("Program completed successfully");

Demo.

If you are running in an environment where console output is not desirable, call ex.getStackTrace(), and display elements in a way that is consistent with the user interface of your program.

answered Oct 31 '16 at 20:42

Sergey Kalinichenko

714,442
84
1,110
1,523

this was very helpful brother :) but this prints out too much information. I would like the error message to be like the one java gives. java.lang.ArrayIndexOutOfBoundsException: 6 at sth.main(sth.java:15) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:266) – Arafe Zawad Sajid Nov 01 '16 at 03:05
Found out how to display the above mentioned lines. :D – Arafe Zawad Sajid Nov 01 '16 at 09:56

score 3 · Accepted Answer · answered Oct 31 '16 at 20:47

In Java you can use printStackTrace on any exception object to get the stack trace printed by Java. In your case a minimal:

try {
    // Throw an IndexOutOfBoundsException
} catch (IndexOutOfBoundsException ex) {
    ex.printStackTrace();
}

This prints the stack trace to System.err. You can also pass it a print stream or even System.out to print to that particular stream.

Additionally, if you use java logger, you can use:

logger.log(<LOG_LEVEL>, <LOG_MESSAGE>, ex);

to log the exception. For more details see: https://docs.oracle.com/javase/7/docs/api/java/util/logging/Logger.html

score 0 · Answer 3 · answered Oct 31 '16 at 20:42

0

You can use

ex.GetMessage()

Thanks

answered Oct 31 '16 at 20:42

Jose Gomez

11
1

says "cannot find symbol" I guess the method should be ex.getMessage() but still I do not get any details of the error. In fact I do not get any error message at all :/ – Arafe Zawad Sajid Oct 31 '16 at 21:23
This does not answer the user's question. – Joe C Oct 31 '16 at 21:55

score 0 · Answer 4 · answered Nov 01 '16 at 09:53

Got this from one of my teachers. Might be helpful for other beginners like me. (This is not a part of any h.w./assignment/etc. Curiosity.)

public class ExceptionDemo{
public static void main(String[] args){
    int[] array = new int[2];
    try {
        System.out.println(array[100]);//non-existent
    } catch (IndexOutOfBoundsException ex){
        StackTraceElement[] e = ex.getStackTrace();
        System.err.println("Got error= " + ex + "\n"+
                           "in file "+e[0].getFileName() +"\n"+
                           "in class "+e[0].getClassName() +"\n"+
                           "in method "+e[0].getMethodName() +"\n"+
                           "in line "+e[0].getLineNumber());
        System.err.println("Full trace= ");
        ex.printStackTrace(System.err);
    }
    System.out.println("As Salamu Alaikum");
  }
}

How to display a detailed error message using try{ }catch(){ } blocks

4 Answers4