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Tip of the Day
Language: Java
Expertise: Advanced
Apr 3, 2000



Building the Right Environment to Support AI, Machine Learning and Deep Learning

Stacks to Strings Conversion

Sometimes it is useful to be able to capture the output from a stack dump, redirect it to a string, and then, perhaps, to a window. Here is an example which contains a snippet with two methods for capturing output from an exception. The first code segment in the method ExceptionToString redirects the output from printStackTrace to a PrintWriter object, which is, in turn, bound to a StringWriter. Then grab the StringWriter contents and insert it into a real String.

The rest of the code in ExceptionToString directs all output on System.err to a byte array, which can then be printed or otherwise manipulated. Note that the first code segment handle a single event, whereas the second segment redirects all error output.
import java.io.*;
public class ExceptionToString {
  public ExceptionToString() {
    try {
      int zero= 0;
      System.out.println("Causing exception with 1/0 "+1/zero);
    } catch (Exception e) {
      StringWriter swriter = new StringWriter();
      e.printStackTrace(new PrintWriter(swriter));
      String text = swriter.toString();
      System.out.println("Caught individual exception " + text);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    System.setErr( new PrintStream( baos ) );
    try {
      int zero= 0;
      System.out.println("Causing exception with 1/0" + 1/zero);
    } catch (Exception e) {
    byte []output = baos.toByteArray();
    String f = new String( output );
    System.out.println("Caught exception text = "+f);
  public static void main(String []args) {
    new ExceptionToString();
Manoj K.
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