001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.util;
018
019import java.io.IOException;
020import java.io.InterruptedIOException;
021import java.io.LineNumberReader;
022import java.io.PrintWriter;
023import java.io.StringReader;
024import java.io.StringWriter;
025import java.lang.reflect.UndeclaredThrowableException;
026import java.util.ArrayList;
027import java.util.List;
028
029/**
030 * Helps with Throwable objects.
031 */
032public final class Throwables {
033
034    /**
035     * Has no effect on Java 6 and below.
036     *
037     * @param throwable a Throwable
038     * @param suppressedThrowable a suppressed Throwable
039     * @see Throwable#addSuppressed(Throwable)
040     * @deprecated If compiling on Java 7 and above use {@link Throwable#addSuppressed(Throwable)}. Marked as deprecated because Java 6 is
041     *             deprecated. Will be removed in 2.5.
042     */
043    @Deprecated
044    public static void addSuppressed(final Throwable throwable, final Throwable suppressedThrowable) {
045        throwable.addSuppressed(suppressedThrowable);
046    }
047
048    /**
049     * Has no effect on Java 6 and below.
050     *
051     * @param throwable a Throwable
052     * @return see Java 7's {@link Throwable#getSuppressed()}
053     * @see Throwable#getSuppressed()
054     * @deprecated If compiling on Java 7 and above use {@link Throwable#getSuppressed()}. Marked as deprecated because Java 6 is
055     *             deprecated. Will be removed 2.5.
056     */
057    @Deprecated
058    public static Throwable[] getSuppressed(final Throwable throwable) {
059        return throwable.getSuppressed();
060    }
061
062    /**
063     * Returns true if the getSuppressed method is available.
064     * 
065     * @return True if getSuppressed is available. As of 2.4, always returns true.
066     * @deprecated Will be removed in 2.5. As of 2.4, always returns true.
067     */
068    @Deprecated
069    public static boolean isGetSuppressedAvailable() {
070        return true;
071    }
072
073    /**
074     * Converts a Throwable stack trace into a List of Strings
075     *
076     * @param throwable the Throwable
077     * @return a List of Strings
078     */
079    public static List<String> toStringList(final Throwable throwable) {
080        final StringWriter sw = new StringWriter();
081        final PrintWriter pw = new PrintWriter(sw);
082        try {
083            throwable.printStackTrace(pw);
084        } catch (final RuntimeException ex) {
085            // Ignore any exceptions.
086        }
087        pw.flush();
088        final List<String> lines = new ArrayList<>();
089        final LineNumberReader reader = new LineNumberReader(new StringReader(sw.toString()));
090        try {
091            String line = reader.readLine();
092            while (line != null) {
093                lines.add(line);
094                line = reader.readLine();
095            }
096        } catch (final IOException ex) {
097            if (ex instanceof InterruptedIOException) {
098                Thread.currentThread().interrupt();
099            }
100            lines.add(ex.toString());
101        } finally {
102            Closer.closeSilently(reader);
103        }
104        return lines;
105    }
106
107    /**
108     * Rethrows a {@link Throwable}, wrapping checked exceptions into an {@link UndeclaredThrowableException}.
109     *
110     * @param t the Throwable to throw.
111     * @throws RuntimeException             if {@code t} is a RuntimeException
112     * @throws Error                        if {@code t} is an Error
113     * @throws UndeclaredThrowableException if {@code t} is a checked Exception
114     * @since 2.1
115     */
116    public static void rethrow(final Throwable t) {
117        if (t instanceof RuntimeException) {
118            throw (RuntimeException) t;
119        }
120        if (t instanceof Error) {
121            throw (Error) t;
122        }
123        throw new UndeclaredThrowableException(t);
124    }
125
126    private Throwables() {
127    }
128
129}