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   /*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    *   https://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.
   */
  package io.netty.util.internal;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.PrintStream;
  import java.util.List;
  
  public final class ThrowableUtil {
  
      private ThrowableUtil() { }
  
      /**
       * Set the {@link StackTraceElement} for the given {@link Throwable}, using the {@link Class} and method name.
       */
      public static <T extends Throwable> T unknownStackTrace(T cause, Class<?> clazz, String method) {
          cause.setStackTrace(new StackTraceElement[] { new StackTraceElement(clazz.getName(), method, null, -1)});
          return cause;
      }
  
      /**
       * Gets the stack trace from a Throwable as a String.
       *
       * @param cause the {@link Throwable} to be examined
       * @return the stack trace as generated by {@link Throwable#printStackTrace(java.io.PrintWriter)} method.
       */
      public static String stackTraceToString(Throwable cause) {
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          PrintStream pout = new PrintStream(out);
          cause.printStackTrace(pout);
          pout.flush();
          try {
              return new String(out.toByteArray());
          } finally {
              try {
                  out.close();
              } catch (IOException ignore) {
                  // ignore as should never happen
              }
          }
      }
  
      public static boolean haveSuppressed() {
          return PlatformDependent.javaVersion() >= 7;
      }
  
      @SuppressJava6Requirement(reason = "Throwable addSuppressed is only available for >= 7. Has check for < 7.")
      public static void addSuppressed(Throwable target, Throwable suppressed) {
          if (!haveSuppressed()) {
              return;
          }
          target.addSuppressed(suppressed);
      }
  
      public static void addSuppressedAndClear(Throwable target, List<Throwable> suppressed) {
          addSuppressed(target, suppressed);
          suppressed.clear();
      }
  
      public static void addSuppressed(Throwable target, List<Throwable> suppressed) {
          for (Throwable t : suppressed) {
              addSuppressed(target, t);
          }
      }
  
      @SuppressJava6Requirement(reason = "Throwable getSuppressed is only available for >= 7. Has check for < 7.")
      public static Throwable[] getSuppressed(Throwable source) {
          if (!haveSuppressed()) {
              return EmptyArrays.EMPTY_THROWABLES;
          }
          return source.getSuppressed();
      }
  }