CODEWITHSUNDEEP
javastack-tracetostring
ripper234
ripper234

Reputation: 230296

How can I convert a stack trace to a string?

What is the easiest way to convert the result of Throwable.getStackTrace() to a string that depicts the stacktrace?

Upvotes: 1744

Views: 789439

Answers (30)

dutoitns
dutoitns

Reputation: 2273

The question has been answered, just sharing my method because it's slightly different than the solutions already shared.

/**
 * Get the stacktrace of a {@link Throwable}.
 * The stacktrace will be returned in the form of a string. 
 */
public static String getStackTrace(Throwable theException) {
    Assert.isNotNull(theException);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    PrintWriter printWriter = new PrintWriter(baos, true);
    theException.printStackTrace(printWriter);
    String stackTrace = baos.toString();
    try {
        printWriter.close();
        baos.close();
    } catch(IOException dontCare) {
    }
    return stackTrace;
}

Upvotes: 1

stumbav
stumbav

Reputation: 1709

Guava's Throwables class

If you have the actual Throwable instance, Google Guava provides Throwables.getStackTraceAsString().

Example:

String s = Throwables.getStackTraceAsString ( myException ) ;

This uses printStackTrace under the covers so it outputs a recurisve, trimmed stack trace (i.e., one where frames common to multiple causes in the cause chain are printed only once).

Upvotes: 160

samthebest
samthebest

Reputation: 31553

Scala version

def stackTraceToString(e: Exception): String = {
  import java.io.{PrintWriter, StringWriter}
  val sw = new StringWriter()
  e.printStackTrace(new PrintWriter(sw))
  sw.toString
}

Upvotes: 5

Oliver Hoffmann
Oliver Hoffmann

Reputation: 140

Shortcut Kotlin to write a stacktrace into an existing StringBuilder:

This version is very fast as it avoids creating a temporary string and copying it around

private fun StringBuilder.appendStackTrace(thr: Throwable) =
    thr.printStackTrace(object : PrintWriter(StringWriter()) {
        override fun println(x: Any?) {
            [email protected](x)
            [email protected]('\n')
        }
    })

You can call it like:

val s = buildString {
    append("Some text before the stack trace ...\n")
    appendStackTrace(throwable)
    append("Some other stuff")
}

Upvotes: 0

vonox7
vonox7

Reputation: 1167

Kotlin >= 1.4

Use the built-in function stackTraceToString() on a Throwable.

Kotlin < 1.4

Extending the Throwable class will give you the String property error.stackTraceString:

val Throwable.stackTraceString: String
  get() {
    val sw = StringWriter()
    val pw = PrintWriter(sw)
    this.printStackTrace(pw)
    return sw.toString()
  }

Upvotes: 20

Pengcheng Zhang
Pengcheng Zhang

Reputation: 141

if you are using Java 8, try this

Arrays.stream(e.getStackTrace())
                .map(s->s.toString())
                .collect(Collectors.joining("\n"));

you can find the code for getStackTrace() function provided by Throwable.java as :

public StackTraceElement[] getStackTrace() {
    return getOurStackTrace().clone();
}

and for StackTraceElement, it provides toString() as follows:

public String toString() {
    return getClassName() + "." + methodName +
        (isNativeMethod() ? "(Native Method)" :
         (fileName != null && lineNumber >= 0 ?
          "(" + fileName + ":" + lineNumber + ")" :
          (fileName != null ?  "("+fileName+")" : "(Unknown Source)")));
}

So just join the StackTraceElement with "\n".

Upvotes: 14

Andrey Sarul
Andrey Sarul

Reputation: 1613

I wonder why no one mentioned ExceptionUtils.getStackFrames(exception)

For me it's the most convenient way to dump stacktrace with all its causes to the end:

String.join("\n", ExceptionUtils.getStackFrames(exception));

Upvotes: 3

ivanjermakov
ivanjermakov

Reputation: 1294

With Java 8 Stream API you can do something like this:

Stream
    .of(throwable.getStackTrace())
    .map(StackTraceElement::toString)
    .collect(Collectors.joining("\n"));

It will take array of stack trace elements, convert them to string and join into multiline string.

Upvotes: 9

Baked Inhalf
Baked Inhalf

Reputation: 3735

Print the stack trace to a PrintStream, then convert it to a String:

// ...

catch (Exception e)
{
    ByteArrayOutputStream out = new ByteArrayOutputStream(); 
    e.printStackTrace(new PrintStream(out));
    String str = new String(out.toByteArray());

    System.out.println(str);
}

Upvotes: 26

Brian Agnew
Brian Agnew

Reputation: 272377

Use Throwable.printStackTrace(PrintWriter pw) to send the stack trace to an appropriate writer.

import java.io.StringWriter;
import java.io.PrintWriter;

// ...

StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
e.printStackTrace(pw);
String sStackTrace = sw.toString(); // stack trace as a string
System.out.println(sStackTrace);

Upvotes: 2384

Brian_Entei
Brian_Entei

Reputation: 533

I wrote a few methods for this a while ago, so I figured why not throw my two cents at this.

/** @param stackTraceElements The elements to convert
 * @return The resulting string */
public static final String stackTraceElementsToStr(StackTraceElement[] stackTraceElements) {
    return stackTraceElementsToStr(stackTraceElements, "\n");
}

/** @param stackTraceElements The elements to convert
 * @param lineSeparator The line separator to use
 * @return The resulting string */
public static final String stackTraceElementsToStr(StackTraceElement[] stackTraceElements, String lineSeparator) {
    return stackTraceElementsToStr(stackTraceElements, lineSeparator, "");
}

/** @param stackTraceElements The elements to convert
 * @param lineSeparator The line separator to use
 * @param padding The string to be used at the start of each line
 * @return The resulting string */
public static final String stackTraceElementsToStr(StackTraceElement[] stackTraceElements, String lineSeparator, String padding) {
    String str = "";
    if(stackTraceElements != null) {
        for(StackTraceElement stackTrace : stackTraceElements) {
            str += padding + (!stackTrace.toString().startsWith("Caused By") ? "\tat " : "") + stackTrace.toString() + lineSeparator;
        }
    }
    return str;
}

/** @param stackTraceElements The elements to convert
 * @return The resulting string */
public static final String stackTraceCausedByElementsOnlyToStr(StackTraceElement[] stackTraceElements) {
    return stackTraceCausedByElementsOnlyToStr(stackTraceElements, "\n");
}

/** @param stackTraceElements The elements to convert
 * @param lineSeparator The line separator to use
 * @return The resulting string */
public static final String stackTraceCausedByElementsOnlyToStr(StackTraceElement[] stackTraceElements, String lineSeparator) {
    return stackTraceCausedByElementsOnlyToStr(stackTraceElements, lineSeparator, "");
}

/** @param stackTraceElements The elements to convert
 * @param lineSeparator The line separator to use
 * @param padding The string to be used at the start of each line
 * @return The resulting string */
public static final String stackTraceCausedByElementsOnlyToStr(StackTraceElement[] stackTraceElements, String lineSeparator, String padding) {
    String str = "";
    if(stackTraceElements != null) {
        for(StackTraceElement stackTrace : stackTraceElements) {
            str += (!stackTrace.toString().startsWith("Caused By") ? "" : padding + stackTrace.toString() + lineSeparator);
        }
    }
    return str;
}

/** @param e The {@link Throwable} to convert
 * @return The resulting String */
public static final String throwableToStrNoStackTraces(Throwable e) {
    return throwableToStrNoStackTraces(e, "\n");
}

/** @param e The {@link Throwable} to convert
 * @param lineSeparator The line separator to use
 * @return The resulting String */
public static final String throwableToStrNoStackTraces(Throwable e, String lineSeparator) {
    return throwableToStrNoStackTraces(e, lineSeparator, "");
}

/** @param e The {@link Throwable} to convert
 * @param lineSeparator The line separator to use
 * @param padding The string to be used at the start of each line
 * @return The resulting String */
public static final String throwableToStrNoStackTraces(Throwable e, String lineSeparator, String padding) {
    if(e == null) {
        return "null";
    }
    String str = e.getClass().getName() + ": ";
    if((e.getMessage() != null) && !e.getMessage().isEmpty()) {
        str += e.getMessage() + lineSeparator;
    } else {
        str += lineSeparator;
    }
    str += padding + stackTraceCausedByElementsOnlyToStr(e.getStackTrace(), lineSeparator, padding);
    for(Throwable suppressed : e.getSuppressed()) {
        str += padding + throwableToStrNoStackTraces(suppressed, lineSeparator, padding + "\t");
    }
    Throwable cause = e.getCause();
    while(cause != null) {
        str += padding + "Caused by:" + lineSeparator + throwableToStrNoStackTraces(e.getCause(), lineSeparator, padding);
        cause = cause.getCause();
    }
    return str;
}

/** @param e The {@link Throwable} to convert
 * @return The resulting String */
public static final String throwableToStr(Throwable e) {
    return throwableToStr(e, "\n");
}

/** @param e The {@link Throwable} to convert
 * @param lineSeparator The line separator to use
 * @return The resulting String */
public static final String throwableToStr(Throwable e, String lineSeparator) {
    return throwableToStr(e, lineSeparator, "");
}

/** @param e The {@link Throwable} to convert
 * @param lineSeparator The line separator to use
 * @param padding The string to be used at the start of each line
 * @return The resulting String */
public static final String throwableToStr(Throwable e, String lineSeparator, String padding) {
    if(e == null) {
        return "null";
    }
    String str = padding + e.getClass().getName() + ": ";
    if((e.getMessage() != null) && !e.getMessage().isEmpty()) {
        str += e.getMessage() + lineSeparator;
    } else {
        str += lineSeparator;
    }
    str += padding + stackTraceElementsToStr(e.getStackTrace(), lineSeparator, padding);
    for(Throwable suppressed : e.getSuppressed()) {
        str += padding + "Suppressed: " + throwableToStr(suppressed, lineSeparator, padding + "\t");
    }
    Throwable cause = e.getCause();
    while(cause != null) {
        str += padding + "Caused by:" + lineSeparator + throwableToStr(e.getCause(), lineSeparator, padding);
        cause = cause.getCause();
    }
    return str;
}

Example:

try(InputStream in = new FileInputStream(file)) {
    ...
} catch(IOException e) {
    String exceptionToString = throwableToStr(e);
    someLoggingUtility.println(exceptionToString);
    ...
}

Prints:

java.io.FileNotFoundException: C:\test.txt (The system cannot find the file specified)
    at java.io.FileInputStream.open0(Native Method)
    at java.io.FileInputStream.open(Unknown Source)
    at java.io.FileInputStream.<init>(Unknown Source)
    at com.gmail.br45entei.Example.main(Example.java:32)

Upvotes: 2

Akira Yamamoto
Akira Yamamoto

Reputation: 4945

public static String getStackTrace(Throwable t) {
    StringWriter sw = new StringWriter();
    t.printStackTrace(new PrintWriter(sw));
    return sw.toString();
}

Upvotes: 31

Prakhar Nigam
Prakhar Nigam

Reputation: 658

 import java.io.PrintWriter;
import java.io.StringWriter;

public class PrintStackTrace {

    public static void main(String[] args) {

        try {
            int division = 0 / 0;
        } catch (ArithmeticException e) {
            StringWriter sw = new StringWriter();
            e.printStackTrace(new PrintWriter(sw));
            String exceptionAsString = sw.toString();
            System.out.println(exceptionAsString);
        }
    }
}

When you run the program, the output will be something similar:

java.lang.ArithmeticException: / by zero
at PrintStackTrace.main(PrintStackTrace.java:9)

Upvotes: 3

Eric
Eric

Reputation: 1291

Few options

  1. StringWriter sw = new StringWriter(); e.printStackTrace(new PrintWriter(sw)); String exceptionAsString = sw.toString();

  2. Using Google Guava lib String stackTrace = Throwables.getStackTraceAsString ( myException ) ;

  3. org.apache.commons.lang.exception.ExceptionUtils.getStackTrace(Throwable)

Upvotes: 3

Jorge Santos
Jorge Santos

Reputation: 414

The solution is to convert the stackTrace of array to string data type. See the following example:

import java.util.Arrays;

try{

}catch(Exception ex){
    String stack = Arrays.toString(ex.getStackTrace());
    System.out.println("stack "+ stack);
}

Upvotes: 4

Andrey Lebedenko
Andrey Lebedenko

Reputation: 1988

My oneliner to convert stack trace to the enclosed multi-line string:

Stream.of(e.getStackTrace()).map((a) -> a.toString()).collect(Collectors.joining("\n", "[", "]"))

Easy to pass to the logger "as is".

Upvotes: 3

Ramanan Durairaj
Ramanan Durairaj

Reputation: 288

Arrays.toString(thrown.getStackTrace())

Is the easiest way to convert the result into String I am using this in my program to print the stack trace

LOGGER.log(Level.SEVERE, "Query Builder Issue Stack Trace : {0} ,Message : {1} objid {2}", new Object[]{Arrays.toString(e.getStackTrace()), e.getMessage(),objId});

Upvotes: 21

Alexander Wessel
Alexander Wessel

Reputation: 411

Warning: This may be a bit off topic, but oh well... ;)

I don't know what the original posters reason was for wanting the stack trace as string in the first place. When the stack trace should end up in an SLF4J/Logback LOG, but no exception was or should be thrown here's what I do:

public void remove(List<String> ids) {
    if(ids == null || ids.isEmpty()) {
        LOG.warn(
            "An empty list (or null) was passed to {}.remove(List). " +
            "Clearly, this call is unneccessary, the caller should " + 
            "avoid making it. A stacktrace follows.", 
            getClass().getName(),
            new Throwable ("Stacktrace")
        );

        return;
    }

    // actual work, remove stuff
}

I like it because it does not require an external library (other than your logging backend, which will be in place most of the time anyway, of course).

Upvotes: 3

Marcelo Glasberg
Marcelo Glasberg

Reputation: 30919

Old question, but I would just like to add the special case where you don't want to print all the stack, by removing some parts you are not actually interested in, excluding certain classes or packages.

Instead of a PrintWriter use a SelectivePrintWriter:

// This filters out this package and up.
String packageNameToFilter = "org.springframework";

StringWriter sw = new StringWriter();
PrintWriter pw = new SelectivePrintWriter(sw, packageNameToFilter);
e.printStackTrace(pw);
String sStackTrace = sw.toString(); 
System.out.println(sStackTrace);

Where the SelectivePrintWriter class is given by:

public class SelectivePrintWriter extends PrintWriter {
    private boolean on = true;
    private static final String AT = "\tat";
    private String internal;

    public SelectivePrintWriter(Writer out, String packageOrClassName) {
        super(out);
        internal = "\tat " + packageOrClassName;
    }

    public void println(Object obj) {
        if (obj instanceof String) {
            String txt = (String) obj;
            if (!txt.startsWith(AT)) on = true;
            else if (txt.startsWith(internal)) on = false;
            if (on) super.println(txt);
        } else {
            super.println(obj);
        }
    }
}

Please note this class may be easily adapted to filter out by Regex, contains or other criteria. Also note it depends upon Throwable implementation details (not likely to change, but still).

Upvotes: 1

eddyrokr
eddyrokr

Reputation: 414

private String getCurrentStackTraceString() {
    StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
    return Arrays.stream(stackTrace).map(StackTraceElement::toString)
            .collect(Collectors.joining("\n"));
}

Upvotes: 11

amar
amar

Reputation: 12187

One can use the following method to convert an Exception stack trace to String. This class is available in Apache commons-lang which is most common dependent library with many popular open sources

org.apache.commons.lang.exception.ExceptionUtils.getStackTrace(Throwable)

Upvotes: 1152

jqno
jqno

Reputation: 15520

WARNING: Does not include cause (which is usually the useful bit!)

public String stackTraceToString(Throwable e) {
    StringBuilder sb = new StringBuilder();
    for (StackTraceElement element : e.getStackTrace()) {
        sb.append(element.toString());
        sb.append("\n");
    }
    return sb.toString();
}

Upvotes: 120

rouble
rouble

Reputation: 18221

Here is a version that is copy-pastable directly into code:

import java.io.StringWriter; 
import java.io.PrintWriter;

//Two lines of code to get the exception into a StringWriter
StringWriter sw = new StringWriter();
new Throwable().printStackTrace(new PrintWriter(sw));

//And to actually print it
logger.info("Current stack trace is:\n" + sw.toString());

Or, in a catch block

} catch (Throwable t) {
    StringWriter sw = new StringWriter();
    t.printStackTrace(new PrintWriter(sw));
    logger.info("Current stack trace is:\n" + sw.toString());
}

Upvotes: 24

IvanRF
IvanRF

Reputation: 7265

Code from Apache Commons Lang 3.4 (JavaDoc):

public static String getStackTrace(final Throwable throwable) {
    final StringWriter sw = new StringWriter();
    final PrintWriter pw = new PrintWriter(sw, true);
    throwable.printStackTrace(pw);
    return sw.getBuffer().toString();
}

The difference with the other answers is that it uses autoFlush on the PrintWriter.

Upvotes: 10

ido flax
ido flax

Reputation: 528

an exapansion on Gala's answer that will also include the causes for the exception:

private String extrapolateStackTrace(Exception ex) {
    Throwable e = ex;
    String trace = e.toString() + "\n";
    for (StackTraceElement e1 : e.getStackTrace()) {
        trace += "\t at " + e1.toString() + "\n";
    }
    while (e.getCause() != null) {
        e = e.getCause();
        trace += "Cause by: " + e.toString() + "\n";
        for (StackTraceElement e1 : e.getStackTrace()) {
            trace += "\t at " + e1.toString() + "\n";
        }
    }
    return trace;
}

Upvotes: 5

Ognjen Galić
Ognjen Galić

Reputation: 2742

Without java.io.* it can be done like this.

String trace = e.toString() + "\n";                     

for (StackTraceElement e1 : e.getStackTrace()) {
    trace += "\t at " + e1.toString() + "\n";
}

And then the trace variable holds your stack trace. Output also holds the initial cause, the output is identical to printStackTrace()

Example, printStackTrace() yields:

java.io.FileNotFoundException: / (Is a directory)
    at java.io.FileOutputStream.open0(Native Method)
    at java.io.FileOutputStream.open(FileOutputStream.java:270)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
    at Test.main(Test.java:9)

The trace String holds, when printed to stdout

java.io.FileNotFoundException: / (Is a directory)
     at java.io.FileOutputStream.open0(Native Method)
     at java.io.FileOutputStream.open(FileOutputStream.java:270)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:101)
     at Test.main(Test.java:9)

Upvotes: 8

Jarek Przyg&#243;dzki
Jarek Przyg&#243;dzki

Reputation: 4412

Printing stack trace to string

import java.io.PrintWriter;
import java.io.StringWriter;

public class StackTraceUtils {
    public static String stackTraceToString(StackTraceElement[] stackTrace) {
        StringWriter sw = new StringWriter();
        printStackTrace(stackTrace, new PrintWriter(sw));
        return sw.toString();
    }
    public static void printStackTrace(StackTraceElement[] stackTrace, PrintWriter pw) {
        for(StackTraceElement stackTraceEl : stackTrace) {
            pw.println(stackTraceEl);
        }
    }
}

It's useful when you want to print the current thread stack trace without creating instance of Throwable - but note that creating new Throwable and getting stack trace from there is actually faster and cheaper than calling Thread.getStackTrace.

Upvotes: 13

Vicky Kapadia
Vicky Kapadia

Reputation: 6081

If you are developing for Android, a far easier way is to use this:

import android.util.Log;

String stackTrace = Log.getStackTraceString(exception);

The format is the same as getStacktrace, for e.g.

09-24 16:09:07.042: I/System.out(4844): java.lang.NullPointerException
09-24 16:09:07.042: I/System.out(4844):   at com.temp.ttscancel.MainActivity.onCreate(MainActivity.java:43)
09-24 16:09:07.042: I/System.out(4844):   at android.app.Activity.performCreate(Activity.java:5248)
09-24 16:09:07.043: I/System.out(4844):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
09-24 16:09:07.043: I/System.out(4844):   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)
09-24 16:09:07.043: I/System.out(4844):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
09-24 16:09:07.043: I/System.out(4844):   at android.app.ActivityThread.access$800(ActivityThread.java:139)
09-24 16:09:07.043: I/System.out(4844):   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
09-24 16:09:07.043: I/System.out(4844):   at android.os.Handler.dispatchMessage(Handler.java:102)
09-24 16:09:07.043: I/System.out(4844):   at android.os.Looper.loop(Looper.java:136)
09-24 16:09:07.044: I/System.out(4844):   at android.app.ActivityThread.main(ActivityThread.java:5097)
09-24 16:09:07.044: I/System.out(4844):   at java.lang.reflect.Method.invokeNative(Native Method)
09-24 16:09:07.044: I/System.out(4844):   at java.lang.reflect.Method.invoke(Method.java:515)
09-24 16:09:07.044: I/System.out(4844):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
09-24 16:09:07.044: I/System.out(4844):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)

Upvotes: 269

Kap&#233;
Kap&#233;

Reputation: 4811

If you don't want to use an external library and you're not developing for Android, you could create an 'extension' method like this:

public static String getStackTraceString(Throwable e) {
    return getStackTraceString(e, "");
}

private static String getStackTraceString(Throwable e, String indent) {
    StringBuilder sb = new StringBuilder();
    sb.append(e.toString());
    sb.append("\n");

    StackTraceElement[] stack = e.getStackTrace();
    if (stack != null) {
        for (StackTraceElement stackTraceElement : stack) {
            sb.append(indent);
            sb.append("\tat ");
            sb.append(stackTraceElement.toString());
            sb.append("\n");
        }
    }

    Throwable[] suppressedExceptions = e.getSuppressed();
    // Print suppressed exceptions indented one level deeper.
    if (suppressedExceptions != null) {
        for (Throwable throwable : suppressedExceptions) {
            sb.append(indent);
            sb.append("\tSuppressed: ");
            sb.append(getStackTraceString(throwable, indent + "\t"));
        }
    }

    Throwable cause = e.getCause();
    if (cause != null) {
        sb.append(indent);
        sb.append("Caused by: ");
        sb.append(getStackTraceString(cause, indent));
    }

    return sb.toString();
}

Upvotes: 4

Tihamer
Tihamer

Reputation: 971

The clever sniping in the first set of comments was very amusing, but it really depends on what you are trying to do. If you don't already have the correct library, then 3 lines of code (as in D. Wroblewski's answer) is perfect. OTOH, if you already have the apache.commons library (as most large projects will), then Amar's answer is shorter. OK, it might take you ten minutes to get the library and install it correctly (less than one if you know what you're doing). But the clock is ticking, so you may not have the time to spare. Jarek Przygódzki had an interesting caveat--"If you don't need nested exceptions".

But what if I do need the full stack traces, nested and all? In that case, the secret is to use apache.common's getFullStackTrace (see http://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/exception/ExceptionUtils.html#getFullStackTrace%28java.lang.Throwable%29)

It saved my bacon. Thanks, Amar, for the hint!

Upvotes: 9

Related Questions