Captures the stack trace associated with this exception. - Java java.lang

Java examples for java.lang:Throwable

Description

Captures the stack trace associated with this exception.

Demo Code

/*/*from ww  w .  j a v  a  2 s  .c o m*/
 * Copyright 1997-2004 The Apache Software Foundation
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.Method;
import java.util.StringTokenizer;

public class Main{
    private static final String LINE_SEPARATOR = System
            .getProperty("line.separator");
    private static final String GET_CAUSE_NAME = "getCause";
    private static final Class[] GET_CAUSE_PARAMTYPES = new Class[0];
    /**
     * Captures the stack trace associated with this exception.
     *
     * @param throwable a <code>Throwable</code>
     * @return an array of Strings describing stack frames.
     */
    public static String[] captureStackTrace(final Throwable throwable) {
        final StringWriter sw = new StringWriter();
        throwable.printStackTrace(new PrintWriter(sw, true));
        return splitStringInternal(sw.toString(), LINE_SEPARATOR);
    }
    /**
     * Generate string for specified exception and the cause of
     * this exception (if any).
     * @param throwable a <code>Throwable</code>
     * @return the stack trace as a <code>String</code>
     */
    public static String printStackTrace(final Throwable throwable) {
        return printStackTrace(throwable, 0, true);
    }
    /**
     * Generate string for specified exception and if printCascading
     * is true will print all cascading exceptions.
     * @param throwable a <code>Throwable</code>
     * @param printCascading if <code>true</code> will print all cascading exceptions
     * @return the stack trace as a <code>String</code>
     */
    public static String printStackTrace(final Throwable throwable,
            final boolean printCascading) {
        return printStackTrace(throwable, 0, printCascading);
    }
    /**
     * Serialize the specified <code>Throwable</code> to a string.
     * Restrict the number of frames printed out to the specified depth.
     * If the depth specified is <code>0</code> then all the frames are
     * converted into a string.
     * @param throwable a <code>Throwable</code>
     * @param depth number of stack trace frames to show
     * @return the stack trace as a <code>String</code>
     */
    public static String printStackTrace(final Throwable throwable,
            final int depth) {
        int dp = depth;
        final String[] lines = captureStackTrace(throwable);

        if (0 == dp || dp > lines.length) {
            dp = lines.length;
        }

        final StringBuffer sb = new StringBuffer();

        for (int i = 0; i < dp; i++) {
            sb.append(lines[i]);
            sb.append(LINE_SEPARATOR);
        }

        return sb.toString();
    }
    /**
     * Generate exception string for specified exception to specified depth
     * and all Cascading exceptions if printCascading is true.
     * @param throwable a <code>Throwable</code>
     * @param depth number of stack trace frames to show
     * @param printCascading if <code>true</code> will print all cascading exceptions
     * @return the stack trace as a <code>String</code>
     */
    public static String printStackTrace(final Throwable throwable,
            final int depth, final boolean printCascading) {
        return printStackTrace(throwable, depth, printCascading, true);
    }
    /**
     * Generate exception string for specified exception to specified depth
     * and all Cascading exceptions if printCascading is true. If useReflection
     * is true then the method will also attempt to use reflection to find a
     * method with signature <code>Throwable getCause()</code>. This makes
     * it compatible with JDK1.4 mechanisms for nesting exceptions.
     * @param throwable a <code>Throwable</code>
     * @param depth number of stack trace frames to show
     * @param printCascading if <code>true</code> will print all cascading exceptions
     * @param useReflection if <code>true</code> will use reflection to handle JDK1.4
     *                      nested exceptions
     * @return the stack trace as a <code>String</code>
     */
    public static String printStackTrace(final Throwable throwable,
            final int depth, final boolean printCascading,
            final boolean useReflection) {
        final String result = printStackTrace(throwable, depth);

        if (!printCascading) {
            return result;
        } else {
            final StringBuffer sb = new StringBuffer();
            sb.append(result);

            Throwable cause = getCause(throwable, useReflection);

            while (null != cause) {
                sb.append("rethrown from");
                sb.append(LINE_SEPARATOR);
                sb.append(printStackTrace(cause, depth));

                cause = getCause(cause, useReflection);
            }

            return sb.toString();
        }
    }
    /**
     * Splits the string on every token into an array of stack frames.
     *
     * @param string the string to split
     * @param onToken the token to split on
     * @return the resultant array
     */
    private static String[] splitStringInternal(final String string,
            final String onToken) {
        final StringTokenizer tokenizer = new StringTokenizer(string,
                onToken);
        final String[] result = new String[tokenizer.countTokens()];

        for (int i = 0; i < result.length; i++) {
            result[i] = tokenizer.nextToken();
        }

        return result;
    }
    /**
     * Utility method to get cause of exception.
     * @param throwable a <code>Throwable</code>
     * @param useReflection if <code>true</code> will use reflection to handle JDK1.4
     *                      nested exceptions
     * @return cause of specified exception
     */
    public static Throwable getCause(final Throwable throwable,
            final boolean useReflection) {
        if (throwable instanceof CascadingThrowable) {
            final CascadingThrowable cascadingThrowable = (CascadingThrowable) throwable;
            return cascadingThrowable.getCause();
        } else if (useReflection) {
            try {
                final Class clazz = throwable.getClass();
                final Method method = clazz.getMethod(GET_CAUSE_NAME,
                        GET_CAUSE_PARAMTYPES);
                return (Throwable) method.invoke(throwable, null);
            } catch (final Throwable t) {
                return null;
            }
        } else {
            return null;
        }
    }
}

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